How to Calculate Your TDEE and Macros
Quick Answer
- 1. Calculate your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation: (10 x weight in kg) + (6.25 x height in cm) - (5 x age) +/- offset.
- 2. Multiply BMR by your activity factor (1.2 for sedentary up to 1.9 for very active) to get your TDEE.
- 3. Subtract 500 calories/day to lose ~1 lb/week, add 250-500 to bulk, or eat at maintenance.
- 4. Split calories into macros: typically 30% protein, 35% carbs, 35% fat for balanced nutrition (adjust for goals).
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Calculate My TDEE FreeBMR vs. TDEE: What Is the Difference?
These two acronyms are the foundation of every calorie calculation, and confusing them is the most common mistake beginners make.
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — lying in bed, doing nothing, just keeping your organs functioning. It powers your heartbeat, breathing, brain activity, cell repair, and temperature regulation. For most people, BMR accounts for 60 to 75% of total daily calorie expenditure, according to the National Institutes of Health.
TDEE (Total Daily Energy Expenditure) is your BMR plus all the additional calories you burn through daily movement, exercise, and digesting food. TDEE is the number that actually matters for weight management — it represents the total calories you burn in a 24-hour period.
Think of it this way: BMR is the engine idling. TDEE is the engine idling plus driving, hauling cargo, and running the air conditioning. You need to know your TDEE to set calorie targets that produce real results.
The Mifflin-St Jeor Formula: Step by Step
The Mifflin-St Jeor equation, published in 1990, is the formula recommended by the Academy of Nutrition and Dietetics as the most accurate for estimating BMR. It replaced the older Harris-Benedict equation (1919), which tends to overestimate calorie needs by 5 to 15%.
The Formula
For men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5
For women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161
Worked Example
A 30-year-old man who weighs 180 pounds (81.6 kg) and is 5'10" (177.8 cm):
- (10 x 81.6) = 816
- (6.25 x 177.8) = 1,111.25
- (5 x 30) = 150
- 816 + 1,111.25 - 150 + 5 = 1,782 calories/day (BMR)
This person burns roughly 1,782 calories per day just by existing. But they do not just lie in bed all day — so we need to account for activity.
Activity Multipliers: From BMR to TDEE
To convert BMR to TDEE, multiply by an activity factor. These multipliers come from research by the Food and Agriculture Organization and the World Health Organization:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, little to no exercise |
| Lightly Active | 1.375 | Light exercise 1-3 days/week |
| Moderately Active | 1.55 | Moderate exercise 3-5 days/week |
| Very Active | 1.725 | Hard exercise 6-7 days/week |
| Extra Active | 1.9 | Athlete, physical job + daily training |
Continuing our example: the 30-year-old man exercises 4 days per week (moderately active). His TDEE is 1,782 x 1.55 = 2,762 calories/day.
A common mistake is overestimating activity level. Research published in the International Journal of Obesity found that people overestimate their exercise calorie burn by an average of 51%. When in doubt, choose one level lower than you think.
Macro Ratios for Different Goals
Once you have your TDEE, the next step is dividing those calories into macronutrients: protein, carbohydrates, and fat. Each gram of protein and carbohydrate contains 4 calories, while each gram of fat contains 9 calories.
For Fat Loss (Cutting)
Calorie target: TDEE minus 500 calories (roughly 1 pound of fat loss per week).
- Protein: 40% of calories (1.0-1.2g per pound of body weight). High protein during a cut preserves muscle mass. A 2016 meta-analysis in the Journal of the International Society of Sports Nutrition confirmed that higher protein intake during caloric restriction results in significantly more fat loss and less muscle loss.
- Fat: 25-30% of calories (minimum 0.3g per pound for hormonal health).
- Carbs: Remaining calories (30-35%).
For Maintenance
Calorie target: Eat at your TDEE.
- Protein: 30% of calories (0.7-1.0g per pound of body weight).
- Fat: 30-35% of calories.
- Carbs: 35-40% of calories.
For Muscle Gain (Bulking)
Calorie target: TDEE plus 250-500 calories (lean bulk) or TDEE plus 500+ (aggressive bulk).
- Protein: 25-30% of calories (0.8-1.0g per pound of body weight).
- Fat: 25-30% of calories.
- Carbs: 40-50% of calories. Carbs fuel intense training and support recovery. A study in the Journal of Strength and Conditioning Research found that adequate carbohydrate intake improved resistance training performance by up to 20%.
How to Track Your Macros
Getting Started
Use a food tracking app like MyFitnessPal, Cronometer, or MacroFactor for at least 2 to 4 weeks when starting out. The goal is not to track forever — it is to build an intuitive sense of portion sizes and macro content. Research from the University of Arkansas found that people who tracked food intake for at least 15 minutes per day lost significantly more weight than those who did not track.
Practical Tips
- Weigh your food for the first 2 weeks. Most people underestimate portions by 30-50%.
- Focus on protein first. Hit your protein target, then fill in carbs and fat around it.
- Aim for consistency, not perfection. Being within 5-10% of your macro targets daily is excellent.
- Use weekly averages. One high-calorie day does not ruin your progress if the weekly total is on target.
Common Mistakes to Avoid
Setting Calories Too Low
Crash dieting (eating significantly below BMR) triggers metabolic adaptation, muscle loss, and eventual rebound weight gain. The NIH recommends never eating below 1,200 calories/day for women or 1,500 for men without medical supervision. A moderate deficit of 500 calories below TDEE is sustainable and effective.
Ignoring the Thermic Effect of Food
Your body burns calories digesting food — this is called the thermic effect of food (TEF). Protein has the highest TEF at 20-30%, meaning if you eat 100 calories of protein, your body uses 20-30 of those calories just to digest it. Carbs have a TEF of 5-10%, and fat has 0-3%. This is one reason high-protein diets tend to produce better results.
Not Adjusting Over Time
Your TDEE is not a fixed number. As you lose weight, your body needs fewer calories. As you gain muscle, your BMR increases. Recalculate every 10 to 15 pounds of change, or use our free TDEE calculator to check your numbers regularly.
The Bottom Line
Calculating your TDEE and macros is the single most impactful step you can take for any body composition goal. The math is straightforward: find your BMR with Mifflin-St Jeor, multiply by your activity level, adjust for your goal, and split into macros. The hard part is consistency — but having accurate numbers gives you a clear target to aim for.
If you want to skip the manual calculations, our free Calorie & TDEE Calculator handles all the math instantly and gives you a personalized macro breakdown for your specific goal.
Frequently Asked Questions
How accurate is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation is considered the most accurate BMR prediction formula for most adults, with a margin of error of about 10%. A 2005 review in the Journal of the American Dietetic Association found it predicted BMR within 10% for 82% of individuals, outperforming the older Harris-Benedict equation. However, it can be less accurate for very muscular individuals, the elderly, and those at extreme body weights. For the most precise measurement, indirect calorimetry (a clinical test measuring oxygen consumption) is the gold standard.
Should I eat back the calories I burn during exercise?
It depends on how you set up your TDEE calculation. If you selected an activity level that already includes your exercise (e.g., 'moderately active' for someone who works out 3-5 days per week), your TDEE already accounts for those calories — do not add them again. If you calculated TDEE using 'sedentary' and then track exercise separately through a fitness tracker, you can eat back roughly 50-75% of the estimated exercise calories. Fitness trackers tend to overestimate calorie burn by 30-90%, so eating back only a portion prevents accidental overeating.
How often should I recalculate my TDEE?
Recalculate every 10 to 15 pounds of weight change, or roughly every 8 to 12 weeks during an active diet phase. As you lose weight, your BMR decreases because your body requires less energy to maintain a smaller mass. This phenomenon — called metabolic adaptation — is why weight loss often plateaus. Recalculating ensures your calorie targets stay accurate as your body changes. You should also recalculate if your activity level changes significantly, such as starting or stopping a regular exercise program.
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