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An estimate, not medical advice. Mifflin-St Jeor estimates resting metabolism within about ±10% for most people — it is not a medical measurement. Cut/maintain/bulk figures are planning ranges (TDEE − 500 / TDEE / TDEE + 300), not prescriptions. Consult a professional for medical goals. For the macro split behind these numbers, see our macro calculator.
Try an example: 40-year-old woman, 165 cm, 70 kg, moderate activity
TDEE stands for Total Daily Energy Expenditure: the total number of calories your body burns in a day, including everything from keeping your heart beating to your evening workout. If you have ever wondered why a diet plan says to eat 2,000 calories while your friend thrives on 2,800, the answer is TDEE - it is personal, and it is the single most useful number for anyone trying to lose, maintain or gain weight. Our free TDEE Calculator estimates yours in seconds using the widely respected Mifflin-St Jeor equation.
The calculation happens in two steps. First the tool estimates your Basal Metabolic Rate (BMR) - the calories you would burn lying completely still all day - from your age, sex, height and weight. Then it multiplies that BMR by an activity factor that reflects how much you move, from sedentary desk life up to an extra-active physical job or heavy training schedule. The result is your maintenance calories: eat roughly this amount and your weight should stay stable. From there the calculator also shows sensible cut and bulk ranges, so you can plan a deficit or surplus with real numbers instead of guesswork.
TDEE pairs naturally with our other nutrition tools: check your BMR Calculator for the resting-metabolism figure on its own, the Calorie Calculator for food-based intake estimates, and the Macro Calculator to split your calories into protein, carbs and fat.
The calculator uses the Mifflin-St Jeor equation (1990), the formula most dietitians and researchers prefer for estimating BMR because it validated better than older equations across diverse adults. It comes in two versions:
Men: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5
Women: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161
Next, the tool applies one of five standard activity multipliers to convert BMR into TDEE: sedentary (little or no exercise) x 1.2, lightly active (light exercise 1-3 days a week) x 1.375, moderately active (moderate exercise 3-5 days a week) x 1.55, very active (hard exercise 6-7 days a week) x 1.725, and extra active (very hard exercise or a physical job) x 1.9. These are the classic Harris-Benedict activity factors, and the brief's worked example below shows exactly how they combine.
Finally, the calculator derives three practical targets from your TDEE: a cutting range around TDEE minus 500 kcal per day (roughly a pound of fat loss per week for most people), a maintenance range at TDEE itself, and a bulking range around TDEE plus 300 kcal per day for lean muscle gain. These are presented as ranges, not single magic numbers, because daily expenditure genuinely fluctuates. The tool accepts both metric and imperial units and converts behind the scenes, so enter whichever you are comfortable with. For a quick body-composition snapshot alongside your numbers, our BMI Calculator is one click away.
Let us walk through the exact calculation for a 40-year-old woman who is 165 cm tall, weighs 70 kg, and exercises moderately (3-5 days a week). Using the women's Mifflin-St Jeor formula:
BMR = 10 x 70 + 6.25 x 165 - 5 x 40 - 161
= 700 + 1,031.25 - 200 - 161
= 1,370 kcal/day
That is what her body needs at complete rest. Now apply the moderate-activity multiplier of 1.55:
TDEE = 1,370 x 1.55 = 2,123.5, rounded to about 2,124 kcal/day
Her practical targets follow directly: a cutting range around 1,624 kcal/day (2,124 - 500), maintenance at 2,124 kcal/day, and a lean-bulk range around 2,424 kcal/day (2,124 + 300). Notice how choosing the wrong activity level would swing the answer by hundreds of calories - which is why the honest-activity question matters more than decimal precision in the formula. Try your own numbers in the calculator above and compare: small people with active jobs can easily out-burn larger sedentary people.
An important note on honesty: your TDEE is an estimate, typically within about plus or minus 10 percent of your true measured metabolism - not a medical measurement. The cut, maintain and bulk figures are planning ranges, not prescriptions, and they are not medical advice. Real bodies vary with muscle mass, hormones, sleep, stress and medications in ways no formula captures. If you have a medical condition, are pregnant, are an athlete with extreme training loads, or are pursuing aggressive weight goals, talk to a doctor or registered dietitian rather than following a calculator alone. The smart way to use your TDEE is as a starting point: eat at the target for two to three weeks, watch the scale trend and your energy, then adjust up or down by 100-200 kcal.
BMR (Basal Metabolic Rate) is the calories you burn at complete rest - keeping you alive and warm. TDEE adds everything else: walking, working, fidgeting and exercise. TDEE is always higher than BMR, and it is the number that matters for diet planning.
Count only deliberate movement beyond a desk job. If you walk 8,000 steps daily and lift three times a week, moderate (1.55) is reasonable. If you sit most of the day with no exercise, choose sedentary (1.2) even if it feels harsh - an honest low estimate beats an optimistic high one you cannot sustain.
It is the best-validated predictive equation for most adults, usually landing within about 10 percent of lab-measured metabolism. Very muscular, very lean or much older individuals may fall outside that band, which is why tracking real-world results for a few weeks beats trusting any formula blindly.
The usual suspects: undercounted food intake (oils, sauces and snacks add up fast), an overestimated activity level, or water-weight masking fat loss. Hold the target steady for three weeks, weigh under consistent conditions, and only then adjust downward by 100-200 kcal.
Yes - a lighter body burns fewer calories, so your TDEE drops as you slim down. Recalculate every 5 kg or so, or whenever progress stalls for more than three weeks.
Yes. Switch to imperial units and enter your weight in pounds and height in feet and inches; the tool converts everything to metric internally before applying the formula, so the result is identical.
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