Quick answer: BMR (Basal Metabolic Rate) is the calories your body burns at complete rest. The Mifflin-St Jeor formula — the most accurate for healthy adults — is: men: 10×weight(kg) + 6.25×height(cm) − 5×age + 5; women: same minus 161. Enter your stats below.
Last reviewed: September 2026
Key facts
- BMR is 60–70% of your total daily calorie burn — the energy for breathing, circulation and cell repair at rest.
- The Mifflin-St Jeor equation (1990) is the most accurate BMR predictor for healthy adults.
- Men burn more at rest than women of the same size, mainly due to greater muscle mass.
- BMR falls roughly 1–2% per decade after age 20, mostly from muscle loss.
This free BMR calculator estimates your Basal Metabolic Rate with the Mifflin-St Jeor equation, the formula dietitians consider most accurate. Enter sex, age, weight and height to get your resting calorie burn plus activity-level daily totals. Results update instantly as you type.
Use your BMR as the starting point for any weight plan: eat below your total daily burn to lose weight, above it to gain. Results update instantly as you type.
How to use
- Select your sex and enter your age.
- Enter your weight (kg or lb) and height (cm or in).
- Read your BMR — calories burned at complete rest.
- Find your activity level in the table for your estimated total daily calories.
The Mifflin-St Jeor formula
Women: BMR = 10×W + 6.25×H − 5×A − 161
| Term | Meaning |
|---|---|
| W | Weight in kilograms. |
| H | Height in centimetres. |
| A | Age in years. |
Worked examples
Man, 30 years, 80 kg, 175 cm
BMR = (10 × 80) + (6.25 × 175) − (5 × 30) + 5 = 800 + 1,093.75 − 150 + 5 = 1,749 kcal/day.
Moderately active (×1.55), his total daily need is about 2,711 kcal.
Woman, 30 years, 65 kg, 165 cm
BMR = (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = 650 + 1,031.25 − 150 − 161 = 1,370 kcal/day.
Lightly active (×1.375), her total daily need is about 1,884 kcal.
What affects your BMR
| Factor | Effect |
|---|---|
| Muscle mass | More muscle = higher BMR; muscle burns more than fat at rest. |
| Age | BMR declines ~1–2% per decade after 20. |
| Sex | Men typically have higher BMR due to more lean mass. |
| Body size | Larger bodies need more energy to maintain. |
| Hormones & illness | Thyroid disorders, fever and stress can raise or lower BMR. |
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the calories you burn at complete rest. TDEE (Total Daily Energy Expenditure) is BMR plus everything else — daily activity and exercise. Multiply your BMR by an activity factor (1.2 to 1.9) to estimate TDEE.
Which BMR formula is most accurate?
The Mifflin-St Jeor equation (1990), validated against indirect calorimetry and endorsed by the American Dietetic Association. It beats the older Harris-Benedict formula for both lean and overweight adults.
Can I raise my BMR?
Modestly, yes: building muscle through strength training is the most effective lever, since muscle tissue is metabolically active. Crash dieting does the opposite — it can suppress BMR.
How many calories should I eat to lose weight?
Eat about 300–500 kcal below your TDEE (BMR × activity factor) for steady loss of roughly 0.5 kg per week. Avoid going below your BMR without medical guidance.
Is BMR the same as metabolism?
BMR is the measurable baseline of your metabolism — the energy cost of keeping you alive at rest. Your full metabolism also includes digestion and all physical activity.
Sources
- NIH — Energy balance and metabolic rate references
- ACE Fitness — Mifflin-St Jeor equation and activity factors
Key takeaways
- BMR = resting calorie burn; Mifflin-St Jeor is the gold-standard estimate.
- Multiply BMR by 1.2–1.9 for total daily needs.
- Muscle raises BMR; age lowers it.
- Eat 300–500 kcal under TDEE for steady fat loss.
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