BMR · TDEE · Macros
Mifflin-St Jeor Calculator
Find how many calories you burn a day. This tool uses the Mifflin-St Jeor equation — the resting-energy formula a 2005 systematic review found most accurate for most people — then applies your activity level to estimate your total daily burn, maintenance calories and goal targets. Free, runs in your browser — no app or signup.
How does this calculator work?
It runs in two steps. First it estimates your resting calorie burn (your resting metabolic rate, usually reported as BMR) with the Mifflin-St Jeor equation:
- Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Then it multiplies that by an activity factor (1.2 to 1.9) to estimate your total daily burn (TDEE), and works out maintenance, deficit and surplus targets with a macro split around them. Your maintenance calories are the calories you need to stay the same weight — the same number as your TDEE; eat below it to lose weight, above it to gain. A 30-year-old man at 80 kg and 180 cm, training moderately, gets a resting burn of about 1,780 calories and a TDEE of about 2,759.
| Activity level | Typical week | Factor | Daily burn |
|---|---|---|---|
| Sedentary | little or no exercise | 1.2 | 2,136 kcal |
| Lightly active | exercise 1–3 days/week | 1.375 | 2,448 kcal |
| Moderately active | exercise 3–5 days/week | 1.55 | 2,759 kcal |
| Very active | hard exercise 6–7 days/week | 1.725 | 3,071 kcal |
| Extra active | very hard exercise or a physical job | 1.9 | 3,382 kcal |
Why the Mifflin-St Jeor equation?
Published in 1990 from a study of nearly 500 healthy adults, it was found in a 2005 systematic review to predict measured resting metabolism more accurately than older formulas like Harris-Benedict — which is why the Academy of Nutrition and Dietetics recommends it. In our own comparison across 840 body profiles, the older Harris-Benedict formula read higher than Mifflin-St Jeor 81% of the time — by about 58 calories a day on average.
Learn how it works
- The Mifflin-St Jeor equation, explained
- How TDEE is calculated
- How accurate is the equation?
- BMR vs TDEE — the difference
- BMR vs RMR — are they the same?
- About the equation and its researchers
- Study: how much do the BMR formulas disagree?
These are estimates. The activity factor in particular is a broad approximation — use your result as a starting point and adjust it against your real-world results over two to three weeks.
Common questions
How do you calculate Mifflin-St Jeor?
Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. Women: the same with −161 instead of +5. The result is your resting calorie burn; multiply it by an activity factor of 1.2 to 1.9 for your total daily burn (TDEE).
What are maintenance calories?
Your maintenance calories are the number you need each day to stay the same weight — the same figure as your TDEE. Eat below maintenance to lose weight, above it to gain. This calculator reports your maintenance figure directly.
How many calories should I eat a day?
Eat at your TDEE to maintain weight. To lose, eat roughly 300–500 calories below it; to gain, eat modestly above. Your TDEE is your Mifflin-St Jeor resting figure times an activity factor — the calculator above gives all three targets.
How accurate is the Mifflin-St Jeor calculator?
It uses the formula a 2005 systematic review found most accurate of the common resting-metabolism equations — closer to measured values, for more people, than Harris-Benedict. Treat the output as a well-grounded estimate and adjust it against two to three weeks of real-world results.