What is BMR?
Your Basal Metabolic Rate is the number of calories your body needs to stay alive at complete rest — breathing, circulating blood, regulating temperature, growing cells and running your brain. For most people, BMR makes up 60–70% of all the calories they burn in a day, far more than exercise.
BMR depends mainly on body size, body composition, age and sex. Muscle tissue burns more energy than fat, which is why two people with the same weight can have different BMRs, and why BMR slowly declines with age as muscle mass falls.
The three formulas
| Formula | Year | Best for |
|---|---|---|
| Mifflin-St Jeor | 1990 | Most adults — the most accurate general equation |
| Harris-Benedict (revised) | 1984 | Comparison with older studies and apps |
| Katch-McArdle | 1996 | People who know their body fat %, athletes |
Mifflin-St Jeor: men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5; women: same, but − 161 instead of + 5.
Katch-McArdle: 370 + 21.6 × lean body mass (kg). Because it uses lean mass instead of total weight, it does not over- or under-estimate for very muscular or higher-body-fat people.
BMR vs TDEE
BMR is what you burn lying in bed all day. Your TDEE (Total Daily Energy Expenditure) adds daily movement and exercise. The table under the result multiplies your BMR by standard activity factors from 1.2 (sedentary) to 1.9 (extra active). To plan a diet around a specific goal, use the calorie calculator.
Can you raise your BMR?
- Build muscle with strength training — the most reliable long-term way.
- Eat enough protein; digesting protein burns more energy than carbs or fat.
- Avoid extreme diets. Severe calorie restriction can cause the body to lower its energy use.
- Sleep well — poor sleep is linked to changes in metabolism and appetite.
Results are estimates for healthy adults and not medical advice.
Frequently asked questions
What is a normal BMR?
Roughly 1,400–1,800 calories for women and 1,600–2,200 for men, depending on size and age.
Is BMR the same as RMR?
They are very close. RMR (resting metabolic rate) is measured under less strict conditions and is usually slightly higher. The formulas here estimate both.
Should I eat my BMR to lose weight?
No — eating only your BMR ignores all your activity. Base weight-loss targets on your TDEE minus a moderate deficit.
Why do the three formulas give different numbers?
Each was developed from different study groups. Differences of 50–150 calories are normal.