The number is a population estimate for planning conversations, not a diet and not medical advice. Illness, pregnancy, medications and a body that is not well described by height and weight can move the true need a long way from the figure.
How to use
- Choose female or male, and enter age in years. The form accepts 15 to 80.
- Choose metric or imperial, then enter height and weight in those units.
- Pick the activity line that matches a typical week and press Calculate. Read the BMR and the TDEE separately.
Formula / how it works
The equation that is actually cited. Mifflin and St Jeor published “A new predictive equation for resting energy expenditure in healthy individuals” in the American Journal of Clinical Nutrition in 1990 (volume 51, pages 241–247). Resting energy expenditure, in kilocalories a day, is estimated as 10 × weight in kilograms + 6.25 × height in centimetres − 5 × age in years, then + 5 for men and − 161 for women. That resting figure is what this page labels BMR. The BMR calculator can show the same Mifflin-St Jeor number next to the older Harris-Benedict revision and the Katch-McArdle estimate. This TDEE page stays with Mifflin-St Jeor and then applies one activity factor.
A worked metric case. For a woman of 30 years, 165 cm and 60 kg the resting total is 10×60 + 6.25×165 − 5×30 − 161 = 600 + 1,031.25 − 150 − 161 = 1,320.25, which rounds to 1,320 kcal/day. Moderate activity uses the factor 1.55, and 1,320.25 × 1.55 rounds to 2,046 kcal/day. The page also lists a figure 500 kcal below that and a figure 300 kcal above it. Those gaps are arithmetic on the estimate. They are not a promise about weight change.
Imperial units. Inches are converted with the exact international relation 1 inch = 2.54 cm. Pounds use 1 pound = 0.45359237 kg. A man of 35 years, 70 inches and 180 pounds is 177.8 cm and about 81.6 kg. The male equation gives a resting figure that rounds to 1,758 kcal/day. The light-activity factor 1.375 then rounds to a TDEE of 2,417 kcal/day. If you switch the unit menu and retype the same body in centimetres and kilograms, you should land on the same resting number aside from ordinary rounding.
What the activity factor is, and is not. The five factors are sedentary 1.2, light 1.375, moderate 1.55, hard 1.725 and very hard 1.9. They are the multipliers widely printed beside predictive equations so a resting number can be stretched to a whole day. Mifflin and St Jeor did not derive these five numbers in that paper. Pick the line for the week you actually live, not the week you intend to start. A desk job and a daily walk is often closer to light than to moderate. The factor is the largest source of error on this page, larger than the difference between two honest height measurements.
Cuts, surpluses and the 7,700 kcal story. A kilogram of body fat is often said to hold about 7,700 kcal, so a daily 500 kcal gap is sometimes described as roughly half a kilogram a week. That shortcut ignores water, glycogen, muscle and the way expenditure changes as weight changes. The page prints the 500 kcal and 300 kcal lines so the arithmetic is visible. It does not predict what you will weigh. The calorie calculator and the BMI calculator answer neighbouring questions (a calorie target built a different way, and a height-weight index). None of them diagnoses anything.
Who the equation fits badly. The 1990 sample was adults. A teenager, a pregnant person, someone recovering from illness, or an athlete with a lot of muscle can sit far from the prediction. The form refuses ages outside 15–80, heights outside 120–230 cm and weights outside 30–250 kg rather than printing a casual number for a body outside those boxes. Refusal is not a medical judgment; it is a limit of this form. If a result looks absurd next to what you already eat while your weight is stable, believe the scale over the equation.
Not medical advice. Do not use the cut line as a crash diet. Very low intakes, especially without clinical supervision, are unsafe for some people. Talk with a doctor or a registered dietitian before you change how you eat, train or take medication. The calculation runs in the browser from the numbers you type. It does not store a profile.
Worked examples
Metric, moderate activity
Inputs: Sex: female | Age: 30 | Units: metric | Height: 165 | Weight: 60 | Activity: moderate
Choose female, age 30, units metric, height 165, weight 60 and activity moderate. The resting equation is applied in kilograms and centimetres, then multiplied by 1.55.
Result: Sex: female
Age: 30 years
Units entered: metric
Height used: 165.0 cm
Weight used: 60.0 kg
BMR (Mifflin-St Jeor): 1,320 kcal/day
Activity: Moderate exercise, 3–5 days a week (×1.55)
TDEE: 2,046 kcal/day
Rough maintain: 2,046 kcal/day
Rough cut, about 500 kcal below TDEE: 1,546 kcal/day
Rough surplus, about 300 kcal above TDEE: 2,346 kcal/day
Not medical advice. This is a population estimate, not a prescription.
BMR rounds to 1,320 kcal/day before the activity factor.
Imperial, light activity
Inputs: Sex: male | Age: 35 | Units: imperial | Height: 70 | Weight: 180 | Activity: light
Choose male, age 35, units imperial, height 70, weight 180 and activity light. Inches and pounds are converted before Mifflin-St Jeor runs.
Result: Sex: male
Age: 35 years
Units entered: imperial
Height used: 177.8 cm
Weight used: 81.6 kg
BMR (Mifflin-St Jeor): 1,758 kcal/day
Activity: Light exercise, 1–3 days a week (×1.375)
TDEE: 2,417 kcal/day
Rough maintain: 2,417 kcal/day
Rough cut, about 500 kcal below TDEE: 1,917 kcal/day
Rough surplus, about 300 kcal above TDEE: 2,717 kcal/day
Not medical advice. This is a population estimate, not a prescription.
70 inches is 177.8 cm and 180 pounds is about 81.6 kg.
Use cases
- Seeing a Mifflin-St Jeor resting number and one activity factor on the same page.
- Converting an imperial height and weight before the equation runs.
- Comparing a maintenance estimate with the 500 kcal and 300 kcal arithmetic gaps.
- Bringing a figure to a dietitian instead of treating it as a prescription.
Tips & limitations
- Choose the activity you have, not the one you plan to have.
- Re-enter height and weight if you switch between metric and imperial. The boxes are not converted in place.
- Treat a stable real-world intake as better evidence than the equation when they disagree.
- Read the BMR line and the TDEE line separately so the activity factor stays visible.
FAQ
What does TDEE mean here?
Total daily energy expenditure: the Mifflin-St Jeor resting estimate times the activity factor you picked, in kilocalories a day.
Are the activity multipliers from the 1990 paper?
No. The paper estimates resting expenditure. The factors 1.2, 1.375, 1.55, 1.725 and 1.9 are the common scale applied afterwards.
Why did the form reject my age or height?
Ages outside 15–80, heights outside 120–230 cm and weights outside 30–250 kg are refused. The equation was developed on adults and this form will not invent a result outside those boxes.
Will a 500 kcal gap change my weight by half a kilogram a week?
Not reliably. That story assumes a fixed energy store and a fixed expenditure. Bodies adapt, and water weight moves the scale.
Is this medical advice?
No. It is not a diet, a diagnosis or a target you must hit. Ask a doctor or a registered dietitian before you change how you eat.
Are my height and weight uploaded?
No. The multiplication stays in the browser.
This TDEE figure is an estimate from the Mifflin-St Jeor equation and a general activity multiplier. It is not medical advice, a diet, or a prediction of what you will weigh. Pregnancy, illness, muscle mass and medications change energy needs. Talk with a doctor or a registered dietitian before you cut or add calories.