BMR & TDEE Calculator
Estimate daily resting and activity-adjusted calorie needs. Your work stays on this device whenever possible.
How to use BMR & TDEE Calculator
- Choose Biological Sex and Units, either "Metric (cm & kg)" or "Imperial (inches & lbs)", then enter Age (years), Height and Weight.
- Optionally type Body Fat % (optional for Katch formula); a value above 3 and below 60 adds a third formula.
- Select an Activity Level from Sedentary at 1.2 up to Extremely Active at 1.9.
- Pick a Daily Calorie Goal, from maintaining weight to aggressive loss of 1,000 kcal below maintenance or +500 kcal for bulking.
- Press "Calculate BMR & TDEE" and read all three BMR formulas, maintenance calories, target calories and macros.
Worked example
Select Female, Metric, age 34, height 165, weight 62, Moderately Active (1.55), Standard weight loss. Mifflin BMR = 10 × 62 + 6.25 × 165 − 5 × 34 − 161 = 1,320. Harris-Benedict gives 1,385. TDEE = 1,320.25 × 1.55 = 2,046, so the target is 2,046 − 500 = 1,546 kcal: protein 116 g, carbohydrate 155 g, fat 52 g.
When to use this tool
- Setting a starting calorie target for a gradual fat-loss plan.
- Comparing three BMR equations for the same body measurements.
- Estimating maintenance calories after changing a weekly exercise routine.
Important limitations
Equations estimate resting energy expenditure based on statistical population medians. Factors like thyroid function, hormone levels, and genetic metabolic adaptation can cause deviations of 5-10%.
Frequently asked questions
Which formula sets the maintenance calories?
Total daily energy expenditure always multiplies the Mifflin-St Jeor BMR (Mifflin et al., Am J Clin Nutr 1990: academic.oup.com/ajcn/article-abstract/51/2/241/4695092) by your activity factor. The revised Harris-Benedict (Roza & Shizgal 1984: academic.oup.com/ajcn/article-abstract/40/1/168/4698305) and Katch-McArdle results are displayed for comparison. Results are a statistical estimate, not medical advice.
Why is my target never below 1,200 kcal?
The plan applies a floor of 1,200 kilocalories per day, even if your maintenance minus the deficit is lower. Very low intakes should only be followed under professional supervision.
How are the macros chosen?
The plan uses a fixed split: 30% protein, 40% carbohydrate and 30% fat, converted to grams at 4, 4 and 9 kcal per gram. Athletes or people with medical needs will want a different balance.
What does the Katch-McArdle line need?
A body fat percentage between 3 and 60. It multiplies lean mass by 21.6 and adds 370, so accuracy depends on your body fat estimate, for example one from the body fat tool.
How accurate are BMR estimates?
They are population averages and can miss individual metabolism by a few hundred calories. Track weight over several weeks and adjust the target based on real changes.