BMR Calculator
Your basal metabolic rate (BMR) is the calories your body burns at complete rest. By the Mifflin–St Jeor equation it's 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for men or minus 161 for women — about 1,320 calories a day for a 30-year-old, 165 cm, 60 kg woman. Enter your details to get your BMR (in calories and kJ) and the calories you burn at each activity level; add your body fat % for a Katch–McArdle estimate too.
BMR calculator
| BMR, Mifflin–St Jeor | 1,417 calories/day (5,929 kJ) |
Calories burned per day by activity level
| Sedentary (×1.2) | 1,700 calories |
| Lightly active (×1.375) | 1,950 calories |
| Moderately active (×1.55) | 2,200 calories |
| Very active (×1.725) | 2,440 calories |
| Extra active (×1.9) | 2,690 calories |
BMR by the Mifflin–St Jeor equation. Know your body fat %? Add it to see the Katch–McArdle estimate too. Real needs can be about 10% higher or lower; it's an estimate, not a measurement.
The Mifflin–St Jeor equation
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
In US units the same equation is 4.536 × weight (lb) + 15.88 × height (in) − 5 × age, then +5 or −161. The equation was published in 1990 by Mifflin, St Jeor and colleagues. In a 2005 review for the American Dietetic Association it predicted resting energy use within 10% of measured values for more people than the older Harris–Benedict formula, and it doesn't need a body fat percentage, which most people don't know. For pounds and inches the calculator converts for you (1 lb = 0.4536 kg, 1 in = 2.54 cm).
BMR by weight, age and sex
Quick reference by Mifflin–St Jeor for a woman of 5′4″ (163 cm) and a man of 5′9″ (175 cm). Each inch of height adds about 16 calories; each extra decade of age takes away 50.
| Weight | Woman, 30 | Woman, 60 | Man, 30 | Man, 60 |
|---|---|---|---|---|
| 120 lb (54 kg) | 1,249 | 1,099 | 1,495 | 1,345 |
| 140 lb (64 kg) | 1,340 | 1,190 | 1,585 | 1,435 |
| 160 lb (73 kg) | 1,431 | 1,281 | 1,676 | 1,526 |
| 180 lb (82 kg) | 1,521 | 1,371 | 1,767 | 1,617 |
| 200 lb (91 kg) | 1,612 | 1,462 | 1,858 | 1,708 |
| 220 lb (100 kg) | 1,703 | 1,553 | 1,948 | 1,798 |
| 240 lb (109 kg) | 1,794 | 1,644 | 2,039 | 1,889 |
Katch–McArdle: if you know your body fat
Mifflin–St Jeor works from weight, so two people of the same size get the same BMR even if one carries much more muscle. The Katch–McArdle equation uses lean body mass instead: BMR = 370 + 21.6 × lean mass (kg), where lean mass = weight × (1 − body fat %). It can suit lean, muscular people better — but only if your body fat figure is decent: a DEXA scan or a careful measurement, not a guess. Enter it in the calculator and you'll see both results side by side; the activity table then uses Katch–McArdle. In energy terms, 1 calorie (kcal) = 4.184 kJ.
From BMR to calories per day
To estimate how many calories you burn in a day (TDEE), multiply BMR by an activity factor:
| Activity level | Factor | Example: BMR 1,320 |
|---|---|---|
| Sedentary — desk job, little or no exercise | ×1.2 | 1,580 calories |
| Lightly active — light exercise or walking 1–3 days a week | ×1.375 | 1,820 calories |
| Moderately active — exercise 3–5 days a week | ×1.55 | 2,050 calories |
| Very active — hard exercise 6–7 days a week | ×1.725 | 2,280 calories |
| Extra active — physical job plus training, or twice-a-day training | ×1.9 | 2,510 calories |
What changes your BMR
More weight and more height mean a higher BMR; each year of age lowers it a little, and at the same size men burn more than women, mostly because of more muscle. Muscle is the part you can change: strength training helps keep BMR from dropping as you age or diet. The formula is an estimate — real BMR can differ by about 10% either way.
To turn BMR into a daily target for weight loss or maintenance, use the maintenance calorie calculator; to split calories into protein, carbs and fat, use the macro calculator.
FAQ
What is BMR?
Basal metabolic rate (BMR) is the number of calories your body burns at complete rest in a day — to keep your heart beating, lungs breathing, brain working and body warm. It's usually the largest part of daily energy use.
What is a normal BMR?
It depends on sex, age, height and weight. By the Mifflin–St Jeor equation, a 30-year-old woman who is 165 cm (5′5″) and 60 kg (132 lb) has a BMR of about 1,320 calories a day; a 30-year-old man who is 180 cm (5′11″) and 80 kg (176 lb), about 1,780.
How do I calculate BMR?
With the Mifflin–St Jeor equation: 10 × weight in kg + 6.25 × height in cm − 5 × age in years, then +5 for men or −161 for women. In pounds and inches: 4.536 × weight (lb) + 15.88 × height (in) − 5 × age, then +5 or −161. Multiply the result by an activity factor from 1.2 to 1.9 to estimate the calories you burn per day.
What's the difference between BMR and TDEE?
BMR is what you burn at rest. TDEE (total daily energy expenditure) adds everything else — digesting food, daily movement and exercise — and is the number of calories that keeps your weight stable. The calculator shows both.
What is the Katch–McArdle formula?
It estimates BMR from lean body mass: 370 + 21.6 × lean mass in kg, where lean mass is your weight minus your body fat. It doesn't use age or sex, so it only helps if you know your body fat percentage reasonably well. For an 80 kg (176 lb) man with 20% body fat it gives about 1,752 calories, close to the 1,780 from Mifflin–St Jeor.
Should I eat less than my BMR to lose weight?
Generally no. Eating below your BMR for long makes it hard to get enough protein and nutrients and is difficult to sustain. A moderate deficit from your maintenance calories works better; our diary never sets a target below BMR.