28 min read
Free Macro Calculator Guide: How to Get Accurate Results
A free macro calculator can give you the same quality results as paid coaching programs — if you know how to use it correctly. This guide walks you through every step: how to enter your information accurately, which goal to select, how to interpret your results, and what to do with your macro numbers once you have them.
- Free calculators use the same formulas as paid programs — the Mifflin-St Jeor equation is the gold standard
- Accuracy depends on your inputs — honest activity level selection is the most important factor
- Results are a starting point — adjust based on real-world progress after 2-3 weeks
- Four calculators in one: Our tool covers Daily Macros, Weight Loss, Muscle Gain, and Keto
- No body fat % required — Mifflin-St Jeor works without this measurement
What a Free Macro Calculator Does
A macro calculator takes your personal information — gender, age, weight, height, and activity level — and uses a scientifically validated formula to estimate how many calories you need each day. It then breaks those calories into specific gram targets for protein, carbohydrates, and fat based on your chosen goal.
The entire process involves three calculations happening behind the scenes:
- BMR calculation — Your Basal Metabolic Rate, the calories your body burns at complete rest
- TDEE calculation — Your Total Daily Energy Expenditure, BMR multiplied by your activity factor
- Macro split — Your TDEE adjusted for your goal (deficit or surplus), then divided into protein, carbs, and fat grams
Our free macro calculator does all of this instantly. But understanding the process helps you make better decisions about your inputs and interpret your results more effectively. For the full mathematical breakdown, see our how to calculate macros guide.
Our calculator uses the Mifflin-St Jeor equation, validated by the American Dietetic Association as the most accurate BMR formula. It then applies research-backed activity multipliers and goal-specific macro ratios to give you personalized targets in seconds.
Calculator Accuracy Comparison
Not all macro calculators are created equal. The accuracy of any calculator depends primarily on which BMR formula it uses. A 2005 systematic review in the Journal of the American Dietetic Association evaluated the most common predictive equations. Here is how they compare:
| BMR Formula | Accuracy | Requires Body Fat % | Best For | Common Error |
|---|---|---|---|---|
| Mifflin-St Jeor | Within ~10% | No | General population (our calculator uses this) | Slightly overestimates in obese individuals |
| Harris-Benedict (revised) | Within ~12-15% | No | Historical reference, still widely used | Overestimates by 5-15% on average |
| Katch-McArdle | Within ~8% | Yes | Lean individuals who know their body fat % | Inaccurate if body fat estimate is wrong |
| Cunningham | Within ~8-10% | Yes | Athletes and highly active individuals | Overestimates for sedentary people |
| Owen | Within ~12% | No | Clinical settings | Underestimates in active individuals |
Formula Accuracy Comparison
Our calculator uses the Mifflin-St Jeor equation because it offers the best combination of accuracy and practicality — it does not require a body fat percentage measurement, which most people do not have accurately. The Dietary Guidelines for Americans and most clinical nutrition guidelines reference this formula as the standard.
Understanding Calorie and Macro Relationships
Before using any calculator, it helps to understand how calories and macros relate to each other. Each macronutrient provides a specific amount of energy:
| Macronutrient | Calories per Gram | Primary Function | Typical Range |
|---|---|---|---|
| Protein | 4 calories | Muscle building, tissue repair, enzymes | 25-40% of calories |
| Carbohydrates | 4 calories | Primary energy source, brain function | 20-50% of calories |
| Fat | 9 calories | Hormone production, vitamin absorption | 20-35% of calories |
| Alcohol | 7 calories | None (empty calories) | Should be minimized |
Calorie Density by Macronutrient
Notice that fat contains more than double the calories of protein or carbohydrates per gram. This is why high-fat foods are calorie-dense and why portion accuracy matters most with oils, nuts, and fatty meats. For more on the relationship between calories and macros, see our calorie and macro calculator guide.
How to Use Our Free Macro Calculator
Our calculator has four specialized tabs, each designed for a specific goal. Here is how to use each one for the best results.
Tab 1: Daily Macros (General Purpose)
This is the default calculator and works for any goal — weight loss, maintenance, or muscle gain. Use this tab when you want flexibility to choose your own goal from a dropdown.
How to use it:
- Select your gender (male or female)
- Enter your age, weight in pounds, and height in feet and inches
- Choose your activity level from the dropdown
- Select your goal: Lose Weight, Maintain Weight, or Build Muscle
- Click "Calculate My Macros"
Tab 2: Weight Loss Calculator
This tab is specifically optimized for fat loss. Instead of a generic "lose weight" option, it lets you choose the size of your caloric deficit. For a complete weight loss strategy, see our macros for weight loss guide.
Deficit options:
- Small (-250 cal): Best for already lean individuals who want to minimize muscle loss. Produces about 0.5 lb loss per week.
- Moderate (-500 cal): The recommended option for most people. Produces about 1 lb loss per week.
- Aggressive (-750 cal): Best for significantly overweight individuals who can tolerate a larger deficit. Produces about 1.5 lbs loss per week.
| Deficit Size | Daily Deficit | Weekly Loss | Best For | Sustainability |
|---|---|---|---|---|
| Small | 250 cal | ~0.5 lb | Already lean, muscle preservation | High |
| Moderate | 500 cal | ~1.0 lb | Most people | Moderate-High |
| Aggressive | 750 cal | ~1.5 lb | Significantly overweight | Moderate |
| Very Aggressive | 1000+ cal | ~2+ lb | Medical supervision only | Low |
Deficits larger than 750 calories per day significantly increase muscle loss risk, metabolic adaptation, and are difficult to sustain. Unless medically supervised, stick to moderate deficits for better long-term results.
Tab 3: Muscle Gain Calculator
This tab calculates macros for building muscle with a caloric surplus. It uses a higher carb ratio to fuel intense training. For a complete bulking guide, see our macros for muscle gain article.
Surplus options:
- Lean Bulk (+200 cal): Minimizes fat gain while still supporting muscle growth. Best for experienced lifters.
- Moderate (+350 cal): A balanced approach for steady muscle gain. Recommended for most people.
- Aggressive (+500 cal): Faster muscle growth but more fat gain. Best for underweight beginners.
Tab 4: Keto Calculator
This tab is designed specifically for ketogenic diets. It uses a 70% fat, 25% protein, 5% carb split and lets you choose your net carb limit. For a detailed keto guide, see our keto macro calculator guide.
Carb limit options:
- 20g (Strict Keto): Most effective for entering and maintaining ketosis
- 30g (Standard Keto): Slightly more flexibility while staying in ketosis
- 50g (Liberal Keto): Easier to follow, but ketosis is less guaranteed
Goal-Specific Macro Splits
Different goals require different macro ratios. Here is what our calculator uses for each goal type:
| Goal | Protein | Carbs | Fat | Calorie Adjustment | Rationale |
|---|---|---|---|---|---|
| Weight Loss | 40% | 30% | 30% | -250 to -750 | High protein preserves muscle during deficit |
| Maintenance | 30% | 40% | 30% | 0 | Balanced for general health |
| Muscle Gain | 30% | 45% | 25% | +200 to +500 | Extra carbs fuel training and recovery |
| Keto | 25% | 5% | 70% | Varies | Very low carb for ketosis |
| Low Carb | 35% | 20% | 45% | Varies | Moderate carb restriction |
Visual Macro Split Comparison
Step-by-Step Walkthrough with Examples
Here is a detailed walkthrough of exactly how to use our calculator, using real examples. We will calculate macros for three different people with different goals.
Example 1: Rachel — Weight Loss
Profile: 32-year-old female, 160 lbs, 5'5", exercises 4 times per week, desk job
Goal: Lose 20 lbs at a sustainable pace
Step 1: Navigate to the calculator and select the "Weight Loss" tab.
Step 2: Enter Rachel's details:
- Gender: Female
- Age: 32
- Weight: 160 lbs
- Height: 5 feet, 5 inches
- Activity Level: Moderately Active
- Deficit: Moderate (-500 calories)
Step 3: The calculator processes the Mifflin-St Jeor equation:
- BMR = (10 x 72.6) + (6.25 x 165.1) - (5 x 32) - 161 = 1,397 cal
- TDEE = 1,397 x 1.55 = 2,165 cal
- Target = 2,165 - 500 = 1,665 cal
| Metric | Value | What It Means |
|---|---|---|
| Daily Calories | 1,665 cal | Total calories to eat per day (deficit already applied) |
| Protein | 166g | 40% of calories / 4 cal per gram |
| Carbohydrates | 125g | 30% of calories / 4 cal per gram |
| Fat | 55g | 30% of calories / 9 cal per gram |
| TDEE | 2,165 cal | Maintenance calories before deficit |
| BMR | 1,397 cal | Calories burned at complete rest |
Example 2: Marcus — Muscle Gain
Profile: 25-year-old male, 165 lbs, 5'10", lifts weights 5 days per week
Goal: Build muscle while minimizing fat gain
Using the Muscle Gain tab with a lean bulk (+200 calories):
- BMR = (10 x 74.8) + (6.25 x 177.8) - (5 x 25) + 5 = 1,734 cal
- TDEE = 1,734 x 1.725 = 2,991 cal
- Target = 2,991 + 200 = 3,191 cal
| Macro | Percentage | Grams | Daily Target |
|---|---|---|---|
| Protein | 30% | 239g | Hit this target consistently |
| Carbs | 45% | 359g | Fuel for workouts |
| Fat | 25% | 89g | Hormone support |
Example 3: Linda — Maintenance
Profile: 45-year-old female, 140 lbs, 5'4", moderate activity
Goal: Maintain current weight and body composition
- BMR = (10 x 63.5) + (6.25 x 162.6) - (5 x 45) - 161 = 1,236 cal
- TDEE = 1,236 x 1.55 = 1,916 cal
- Target = 1,916 (no adjustment for maintenance)
| Macro | Percentage | Grams |
|---|---|---|
| Protein | 30% | 144g |
| Carbs | 40% | 192g |
| Fat | 30% | 64g |
Interpreting Your Results
Getting your numbers from the calculator is just the first step. Understanding what they mean and how to use them is where the real value lies.
Your Calorie Target is Already Adjusted
A common confusion: if you selected "Weight Loss," your daily calorie number already includes the deficit. You do not need to subtract anything additional. The number shown is what you should eat each day. If you selected a 500-calorie deficit, the calculator already subtracted those 500 calories from your TDEE.
Protein is Your Priority Macro
Of the three macro numbers, protein is the most important to hit consistently. Research from the International Society of Sports Nutrition consistently shows that adequate protein intake is the single biggest factor in body composition outcomes. If you fall short on carbs or fat on a given day, the impact is minimal. If you consistently fall short on protein, you will lose muscle during a cut or fail to build muscle during a bulk. Learn more in our protein intake guide.
Carbs and Fat are Flexible
While the calculator gives specific carb and fat targets, these are more flexible than protein. As long as total calories and protein are on target, you can shift some calories between carbs and fat based on your preference. Some people prefer higher carbs for workout energy; others prefer more fat for satiety. This flexibility is the foundation of flexible dieting (IIFYM).
Understanding the Calorie Math
Your macro grams and calorie target should approximately match. Here is how to verify:
- Protein grams x 4 = protein calories
- Carb grams x 4 = carb calories
- Fat grams x 9 = fat calories
- Sum of all three should approximately equal your daily calorie target
Using Rachel's numbers: (166 x 4) + (125 x 4) + (55 x 9) = 664 + 500 + 495 = 1,659 calories. Close to her 1,665 target (rounding accounts for the small difference).
Entering Your Information Accurately
The quality of your results depends entirely on the accuracy of your inputs. Here is how to get each one right.
Gender
Select your biological sex. The BMR formula uses different constants for males and females because men typically have more lean mass and higher metabolic rates. This is not about identity — it is about metabolic accuracy. For women-specific guidance, see our macro calculator for women article.
Age
Enter your current age. Metabolism naturally decreases with age — roughly 1-2% per decade after age 20. This is why the formula subtracts 5 calories per year of age. Older adults can find specialized guidance in our macro calculator for seniors guide.
Weight
Use your morning weight (after using the bathroom, before eating or drinking). Weigh yourself on the same scale at the same time. For best accuracy, take the average of 3-5 morning weights over a week.
Height
Use your actual measured height. Many people overestimate their height by 1-2 inches. If unsure, measure yourself against a wall with bare feet. Even a 1-inch difference changes your BMR by approximately 30-40 calories.
Activity Level — The Most Critical Input
This is where most people make mistakes, and it has the largest impact on results. Here is how to select honestly:
| Level | Multiplier | You Should Select This If... | Daily Steps Equivalent |
|---|---|---|---|
| Sedentary | 1.2 | Desk job, drive to work, no structured exercise | <5,000 steps |
| Lightly Active | 1.375 | Desk job but walk regularly, exercise 1-2x per week | 5,000-7,500 steps |
| Moderately Active | 1.55 | Exercise 3-5x per week, moderately active outside the gym | 7,500-10,000 steps |
| Active | 1.725 | Intense exercise 6-7x per week, or active job + exercise | 10,000-12,500 steps |
| Very Active | 1.9 | Athlete training 2x daily, or very physical labor + exercise | >12,500 steps |
When in doubt, choose the lower activity level. A desk worker who goes to the gym 3 times per week is "Moderately Active" at most — not "Active." Overestimating your activity level is the most common cause of macro calculators seeming inaccurate. Examine.com's research confirms that activity overestimation is the leading source of error in calorie calculations.
How Activity Level Affects Your TDEE
To illustrate how dramatically activity level selection impacts your results, here is how the same person's TDEE changes across activity levels (using a BMR of 1,500 calories):
The difference between "Sedentary" and "Very Active" is over 1,000 calories per day. Selecting the wrong activity level can mean the difference between losing 1 pound per week and gaining weight.
When Free Calculators Fall Short
While free macro calculators are excellent tools, there are situations where they have limitations. Understanding these helps you set realistic expectations and know when to seek additional guidance.
Populations Where Standard Formulas Are Less Accurate
| Population | Issue with Standard Calculators | Recommended Approach |
|---|---|---|
| Morbidly obese (BMI 40+) | Overestimates BMR by 10-20% | Use adjusted body weight; consult dietitian |
| Very lean athletes (<10% body fat) | May underestimate energy needs | Use Katch-McArdle formula with known body fat % |
| Elderly (70+) | May overestimate due to age-related muscle loss | Reduce result by 5-10%; monitor closely |
| Teenagers (under 18) | Growth requires additional calories | Consult pediatric dietitian |
| Pregnant or nursing women | Increased caloric needs not accounted for | Work with healthcare provider |
| Medical conditions (diabetes, kidney disease) | May need modified macro ratios | Work with registered dietitian |
If you have diabetes, kidney disease, eating disorders, or other conditions affecting nutrition, please work with a registered dietitian (RD or RDN credential) who can provide personalized recommendations. This calculator is designed for generally healthy adults.
Working with a Dietitian vs Self-Tracking
A common question is whether you need professional help or whether a free calculator and self-tracking are sufficient. The answer depends on your situation, goals, and experience level.
| Factor | Self-Tracking (Free Calculator) | Registered Dietitian |
|---|---|---|
| Macro calculation accuracy | Same formula (Mifflin-St Jeor) | Same formula + clinical assessment |
| Cost | $0 | $100-300 per session |
| Personalization | Based on your self-reported data | Based on clinical evaluation |
| Ongoing adjustments | You make them based on progress | Dietitian adjusts for you |
| Accountability | Self-motivated | Regular check-ins provide accountability |
| Medical conditions | Not equipped to handle | Can accommodate medical needs |
| Eating disorders | Not appropriate | Specialized support available |
| Best for | Healthy adults with clear goals | Complex health situations, competitive athletes |
For the majority of people — healthy adults who want to lose weight, gain muscle, or eat better — a free calculator combined with consistent self-tracking is sufficient and effective. According to the NIH Office of Dietary Supplements, understanding your nutritional needs and tracking intake are foundational steps in improving dietary quality.
Free vs. Paid Macro Calculators: What You Actually Need
Many fitness influencers and coaching companies sell macro calculations for $20-$100 or include them in coaching packages costing $100+ per month. Here is the truth about what you are paying for:
| Feature | Free Calculator | Paid Service ($20-50) | Coaching Package ($100+/mo) |
|---|---|---|---|
| BMR/TDEE Calculation | Same formula | Same formula | Same formula |
| Macro Split | Evidence-based ratios | Evidence-based ratios | Evidence-based ratios |
| Accuracy | Within ~10% | Within ~10% | Within ~10% |
| Meal Plans | Not included | Often included | Usually included |
| Ongoing Adjustments | You adjust based on progress | Usually one-time | Coach adjusts for you |
| Accountability | Self-motivated | None | Regular check-ins |
| Support | Self-guided | Email support maybe | Direct messaging/calls |
The calculation itself is identical across all options. What you pay for with a coach is accountability, meal planning, and someone to make adjustments for you. If you are self-motivated and willing to learn, a free calculator gives you everything you need to succeed.
What to Do After Getting Your Results
Having your macro numbers is just the beginning. Here is how to put them into practice.
Step 1: Set Up a Tracking System
You need a way to track your daily food intake against your macro targets. The most popular options are:
- MyFitnessPal — Largest food database, barcode scanning, free tier available
- Cronometer — More accurate database entries, better micronutrient tracking
- MacroFactor — Adaptive algorithm that adjusts your macros over time based on your actual results
- Lose It! — Simple interface, good for beginners
Enter your macro targets from our calculator into your tracking app as custom goals. For a detailed comparison, see our macro tracking apps review.
Step 2: Plan Your First Week
Do not try to be perfect on day one. Start by tracking what you normally eat for 2-3 days. Then identify the gaps — usually protein is too low and fat is too high. Gradually adjust your meals to hit your targets. Our meal prep for macros guide provides a complete meal planning system.
Step 3: Focus on Protein First
Protein is the hardest macro to hit for most people. Plan your protein sources for each meal before worrying about carbs and fat. A simple structure works well:
| Meal | Protein Source | Approximate Protein | Example Foods |
|---|---|---|---|
| Breakfast | Eggs + egg whites or Greek yogurt | 25-35g | 3 eggs + 2 whites, or 1.5 cups Greek yogurt |
| Lunch | Chicken, turkey, or fish | 35-45g | 5-6 oz grilled chicken breast |
| Snack | Protein shake or cottage cheese | 25-30g | 1 scoop whey + 1/2 cup cottage cheese |
| Dinner | Lean meat, fish, or tofu | 35-45g | 6 oz salmon or 8 oz firm tofu |
| Evening Snack | Greek yogurt or casein shake | 20-25g | 1 cup Greek yogurt or casein shake |
This structure provides 140-180g of protein per day. Adjust portions up or down based on your specific target. For more protein-rich food options, see our best foods for macros guide.
Step 4: Evaluate After 2-3 Weeks
Give the calculator results at least 2-3 weeks of consistent tracking before making changes. Weight fluctuates daily due to water, sodium, carb intake, and other factors. Compare weekly averages, not daily weigh-ins.
How to Interpret Progress and Adjust
After your initial 2-3 week evaluation period, here is how to determine if your macros need adjusting:
| Situation | What It Means | What to Do | Timeline |
|---|---|---|---|
| Losing 0.5-1.5 lbs/week | Calculator is accurate | Keep current macros | Continue 4-8 more weeks |
| Not losing weight | Eating more than you think, or activity overestimated | Reduce calories by 150-200, verify tracking accuracy | Re-evaluate in 2 weeks |
| Losing more than 2 lbs/week | Deficit may be too aggressive | Increase calories by 150-200 to preserve muscle | Re-evaluate in 2 weeks |
| Gaining 0.5-1 lb/month (muscle gain goal) | Surplus is appropriate | Keep current macros | Continue 8-12 weeks |
| Gaining more than 2 lbs/month | Surplus may be too large | Reduce calories by 100-200 | Re-evaluate in 3 weeks |
| Not gaining weight | Not actually in a surplus | Increase calories by 200-300 | Re-evaluate in 2 weeks |
Expected Progress Timeline
Common Mistakes When Using a Macro Calculator
- Using different calculators and getting confused. Pick one calculator, use those numbers, and stick with it for at least 3 weeks. Jumping between calculators and averaging results creates unnecessary confusion.
- Overestimating activity level. This inflates your TDEE and gives you more calories than you actually burn. When in doubt, select the lower activity level.
- Treating results as absolute truth. Calculator results are estimates, not prescriptions. They are a starting point that you fine-tune based on your body's actual response.
- Not tracking food accurately. The best macro targets in the world will not work if you are not measuring and logging your food correctly. Use a food scale, especially in the first month.
- Changing macros too frequently. Give your current targets at least 2-3 weeks before making adjustments. Your weight will fluctuate day to day — this is normal. Only make changes based on multi-week trends.
- Ignoring protein. Many people fixate on total calories while letting protein fall below optimal levels. Protein should be your first priority when planning meals.
- Not accounting for weekends. Many people track diligently Monday-Friday then go off-track on weekends. Two untracked days can erase five days of progress.
- Forgetting liquid calories. Coffee drinks, alcohol, juices, and smoothies all count. A single large latte can be 300+ calories.
For more myths and misconceptions about macro counting, check our macro myths debunked article.
When to Recalculate Your Macros
Your macro targets are not permanent. Use our free calculator to get new numbers when:
- Your weight changes by 10-15 lbs — your BMR shifts as body weight changes
- Your activity level changes — starting or stopping a workout program, changing jobs
- Your goal changes — switching from weight loss to maintenance or muscle gain
- Progress stalls for 3+ weeks — despite accurate tracking and consistent effort
- Every 8-12 weeks — as a general practice to keep your targets current
| Trigger | Action | What Changes |
|---|---|---|
| Lost 10+ lbs | Recalculate with new weight | BMR decreases, new targets slightly lower |
| Gained 10+ lbs | Recalculate with new weight | BMR increases, new targets slightly higher |
| Started new job (more/less active) | Recalculate with new activity level | TDEE changes significantly |
| Changed workout frequency | Recalculate with new activity level | TDEE changes moderately |
| Switching from cutting to bulking | Recalculate with new goal | Calorie target and macro ratios change |
| Plateau for 3+ weeks | Recalculate and reduce by additional 100-200 cal | Account for metabolic adaptation |
For a complete guide on macro adjustments over time, see our how to calculate macros guide, specifically the "Adjusting Macros Over Time" section. If you are transitioning from a diet back to normal eating, our reverse dieting explained guide is essential reading.
Frequently Asked Questions
Free macro calculators that use the Mifflin-St Jeor equation are accurate within approximately 10% for most people. This is the same formula used in clinical settings and paid coaching programs. The calculator provides a strong starting point, but you should fine-tune your targets based on real-world results after 2 to 3 weeks of consistent tracking.
Different calculators may use different BMR formulas (Mifflin-St Jeor, Harris-Benedict, Katch-McArdle), different activity multipliers, or different default macro splits. The Mifflin-St Jeor equation is considered the most accurate for the general population. Variations of 100 to 200 calories between calculators are normal and not a cause for concern.
No. Free macro calculators use the same scientifically validated formulas as paid versions. Paid calculators or coaching services may offer additional features like meal plans, food databases, or ongoing adjustments, but the core calculation is identical. A free calculator gives you everything you need to determine your macro targets.
You need five basic inputs: your gender, age, current weight, height, and activity level. You also need to select your goal (weight loss, maintenance, or muscle gain). No body fat percentage measurement is required when using the Mifflin-St Jeor equation. The more accurate your inputs, the more accurate your results will be.
Track your weight weekly (same time, same conditions) and compare 2-week averages. For weight loss, you should see 0.5 to 1.5 pounds lost per week depending on your deficit. For muscle gain, 0.5 to 1 pound gained per month is realistic. If progress does not match expectations after 3 weeks of consistent tracking, adjust calories by 100 to 200 per day.
A macro calculator is more useful because it provides both your calorie target and the breakdown into protein, carbs, and fat. A calorie-only calculator tells you how much to eat but not what to eat. Knowing your macro targets helps you optimize body composition — lose more fat and less muscle during weight loss, or gain more muscle and less fat during a bulk.
Free macro calculators are designed for generally healthy adults. If you have diabetes, kidney disease, an eating disorder, or other medical conditions that affect nutrition, you should work with a registered dietitian or healthcare provider who can tailor recommendations to your specific needs. A calculator provides a general estimate, not medical advice.
A 2005 systematic review found the Mifflin-St Jeor equation to be the most accurate for estimating resting metabolic rate in healthy adults, within approximately 10%. The Harris-Benedict equation tends to overestimate by 5-15%. The Katch-McArdle formula can be more accurate but requires knowing your body fat percentage, which most people do not have measured precisely.
Yes. If you significantly change your activity level, you should recalculate your macros. Your TDEE changes with activity level, which affects how many calories and macros you need. Use our free calculator to update your numbers whenever your routine changes substantially.
The best macro calculator for beginners uses the Mifflin-St Jeor equation, offers goal-specific tabs, explains results clearly, and is free. Our calculator meets all of these criteria and provides instant results without requiring an account or payment. Beginners should start with the Daily Macros tab for maximum flexibility, then explore our counting macros for beginners guide.
To convert pounds to kilograms, divide by 2.205. To convert inches to centimeters, multiply by 2.54. For example, 180 lbs equals 81.6 kg, and 70 inches equals 177.8 cm. Our calculator accepts both metric and imperial inputs, so you can enter your measurements in whichever system you prefer.
If you underestimate your activity level, the calculator will give you fewer calories than you actually need. This creates a larger deficit than intended, which may lead to faster weight loss but also increased hunger, fatigue, and potential muscle loss. It is generally better to slightly underestimate than overestimate, but be honest about your typical daily activity.
Research and References
This guide is based on peer-reviewed research and established nutritional science guidelines:
- Frankenfield et al. (2005) — Comparison of predictive equations for resting metabolic rate in healthy adults — Journal of the American Dietetic Association
- Jager et al. (2017) — ISSN Position Stand: Protein and Exercise — Journal of the International Society of Sports Nutrition
- Dietary Guidelines for Americans 2020-2025 — U.S. Department of Agriculture and U.S. Department of Health and Human Services
- NIH Office of Dietary Supplements — Nutrient Fact Sheets — National Institutes of Health
- Harvard T.H. Chan School of Public Health — The Nutrition Source
- Mifflin et al. (1990) — A new predictive equation for resting energy expenditure in healthy individuals — American Journal of Clinical Nutrition
- Examine.com — How much protein do you need per day? — Evidence-based nutrition research