What's the difference between BMR and TDEE?

BMR is what your body burns at complete rest. TDEE is BMR plus everything else you do in a day — moving, digesting food, exercising. TDEE is the number that matters for weight management; BMR is the floor it sits on.

Why Mifflin-St Jeor and not Harris-Benedict?

The 1990 Mifflin-St Jeor equation is about 5% more accurate than the older 1919 Harris-Benedict for the modern adult population, per Frankenfield et al. 2005. Both produce similar numbers; Mifflin is the current gold standard for predictive equations.

What about body composition?

Equations that account for lean body mass (Katch-McArdle, Cunningham) are more accurate for athletes with low body fat — but they require knowing your body-fat percentage. For the general population without that input, Mifflin-St Jeor is the better choice.

How accurate is the result?

Within ±10% for most people. If the scale doesn't move after two weeks of eating at your computed TDEE, adjust by ±200 kcal and try again. The activity multiplier is the biggest source of error — people consistently overestimate how much they exercise.

Does TDEE include the calories burned by exercise?

Yes — the activity multiplier rolls exercise into the total. Don't add exercise calories on top of your computed TDEE; you'll double-count.

NEAT (non-exercise activity thermogenesis — fidgeting, walking around, holding posture) is included in the multiplier. NEAT can vary by 800+ kcal/day between people; if you're naturally fidgety, your real TDEE is on the high end of the band.

Should I use TDEE to lose weight?

Use it as a starting point. Eat 300–500 kcal below TDEE for a roughly 0.3–0.5 kg/week loss. Check the scale and waist measurement every 1–2 weeks; if it stalls, drop another 200 kcal or add activity. Faster losses risk muscle loss and metabolic slowdown.

BMR & TDEE Calculator (Mifflin-St Jeor)

Your resting calorie burn, plus what five activity levels add on top.

BMR (basal metabolic rate) is the energy your body uses at complete rest — keeping organs running, replacing cells, holding body temperature. TDEE (total daily energy expenditure) is BMR multiplied by an activity factor that accounts for movement, digestion, and exercise. The calculator below uses the Mifflin-St Jeor equation, the most accurate of the common BMR formulas for general adult populations per a 2005 American Dietetic Association review.

Weight (kg)

Height (cm)

Age (years)

BMR — basal metabolic rate

1,718kcal / day

Energy your body burns at complete rest — heartbeat, breathing, cell maintenance. Add movement on top with the activity multipliers below.

TDEE — total daily energy expenditure

BMR × activity multiplier

Sedentary
Desk job, little or no exercise — ×1.2
2,061kcal
Lightly active
Light exercise 1–3 days a week — ×1.375
2,362kcal
Moderately active
Moderate exercise 3–5 days a week — ×1.55
2,662kcal
Active
Hard exercise 6–7 days a week — ×1.725
2,963kcal
Very active
Hard daily exercise + physical job — ×1.9
3,263kcal

Formula: Mifflin-St Jeor (1990). BMR is a screening estimate, not a clinical measurement. Real-world TDEE varies ±10% from these averages — adjust based on a few weeks of weight-stable eating.

How to use

Enter your stats
Pick sex, choose metric (kg, cm) or imperial (lb, ft/in), then fill in weight, height, and age. The BMR figure updates as you type.
Find the activity level that matches your week
Sedentary = mostly desk-bound. Lightly active = light exercise 1–3 days. Moderate = 3–5 days. Active = 6–7 days. Very active = hard daily training plus a physical job.
Use TDEE as your maintenance calories
Eating at your TDEE keeps weight stable. Subtract 300–500 kcal for slow fat loss; add 200–400 for slow muscle gain. Adjust after two weeks if the scale doesn't move.

Activity multipliers, in plain terms

Level	Multiplier	Looks like
Sedentary	1.2	Desk job, no exercise, drive to work
Lightly active	1.375	Desk job, 1–3 light workouts a week (walks, easy yoga)
Moderately active	1.55	Desk job, 3–5 moderate workouts a week (running, weights)
Active	1.725	6–7 hard sessions a week or a moderately physical job
Very active	1.9	Two daily sessions or a construction / labour job

Frequently asked questions

What's the difference between BMR and TDEE?: BMR is what your body burns at complete rest. TDEE is BMR plus everything else you do in a day — moving, digesting food, exercising. TDEE is the number that matters for weight management; BMR is the floor it sits on.
Why Mifflin-St Jeor and not Harris-Benedict?: The 1990 Mifflin-St Jeor equation is about 5% more accurate than the older 1919 Harris-Benedict for the modern adult population, per Frankenfield et al. 2005. Both produce similar numbers; Mifflin is the current gold standard for predictive equations.
What about body composition?: Equations that account for lean body mass (Katch-McArdle, Cunningham) are more accurate for athletes with low body fat — but they require knowing your body-fat percentage. For the general population without that input, Mifflin-St Jeor is the better choice.
How accurate is the result?: Within ±10% for most people. If the scale doesn't move after two weeks of eating at your computed TDEE, adjust by ±200 kcal and try again. The activity multiplier is the biggest source of error — people consistently overestimate how much they exercise.
Does TDEE include the calories burned by exercise?: Yes — the activity multiplier rolls exercise into the total. Don't add exercise calories on top of your computed TDEE; you'll double-count.
What about NEAT?: NEAT (non-exercise activity thermogenesis — fidgeting, walking around, holding posture) is included in the multiplier. NEAT can vary by 800+ kcal/day between people; if you're naturally fidgety, your real TDEE is on the high end of the band.
Should I use TDEE to lose weight?: Use it as a starting point. Eat 300–500 kcal below TDEE for a roughly 0.3–0.5 kg/week loss. Check the scale and waist measurement every 1–2 weeks; if it stalls, drop another 200 kcal or add activity. Faster losses risk muscle loss and metabolic slowdown.

About

The math behind the answer

Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. Women: same first three terms, then − 161. The 'sex constant' difference reflects the fact that men carry more lean mass on average — but two people with identical lean mass and the same age and stats will have nearly identical BMR regardless of which formula constant you use.

When to ignore the calculator

Pregnancy, lactation, hyperthyroid or hypothyroid conditions, recent significant weight loss (5%+ in the last 6 months), and adolescence all shift BMR away from the prediction. In those cases, work with a clinician or dietitian instead of an online calculator.