How your BMR is calculated
This calculator uses the Mifflin-St Jeor equation, the most accurate of the common formulas for most people. It adds up your weight, your height and your age, with a small adjustment for sex. If you enter your body fat percentage it also shows the Katch-McArdle figure, which is based on lean body mass and tends to suit people who carry more muscle.
Either way it is an estimate. Individual results can differ from the formula by 10 to 15 percent, so use the number as a starting point and adjust after a few weeks of real results.
From BMR to the calories you should eat
Your BMR is only the energy you need lying still. Add the energy you spend moving and you get your TDEE, your total daily burn. Multiply your BMR by the factor that matches your week:
| Activity level | Multiply BMR by |
|---|---|
| Sedentary: desk job, little exercise | 1.2 |
| Lightly active: exercise 1-3 days/week | 1.375 |
| Moderately active: exercise 3-5 days/week | 1.55 |
| Very active: exercise 6-7 days/week | 1.725 |
| Extremely active: physical job + training | 1.9 |
If you are between two levels, pick the lower one. To lose weight, eat a modest amount below your TDEE (about 500 kcal a day gives roughly half a kilo a week), and never go below your lowest safe intake. The result above also shows a daily protein target (about 1.6 g per kilo), which helps keep muscle while you lose fat.
What changes your BMR
- Body size. Bigger bodies burn more at rest, which is why BMR falls as you lose weight.
- Muscle. Muscle uses more energy than fat, so strength training and enough protein help over time.
- Age. BMR drifts down slowly with age, mostly as muscle is lost.
- Sex. Men usually have a higher BMR because they carry more muscle on average.
- Very low-calorie dieting. Eating far too little for long can lower BMR slightly, one more reason not to crash diet.
Use your BMR with the tracker
A single number only goes so far. Save your result to the free weight loss tracker and it compares your BMR and daily target with what you actually eat (from your meal photos) and how much you walk. It then suggests small, doable steps toward your target weight, such as one swap or a ten-minute walk, rather than a whole new diet. See also our guide to losing weight with walking and diet.
Frequently asked questions
What is a good BMR?
There is no single good number. BMR depends on your age, sex, height, weight and muscle mass, so a taller or heavier person has a higher BMR than a shorter or lighter one. For most adult women it lands between about 1,200 and 1,600 kcal a day, and for most men between about 1,500 and 2,000. The useful question is not whether yours is high or low, but what it tells you about how much to eat.
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor, so it includes walking, work and exercise. Eat at your TDEE and your weight stays about the same. Eat a modest amount below it and you lose weight.
Should I eat below my BMR to lose weight?
No. Eating well below your BMR for weeks makes you tired, hungry and more likely to lose muscle and rebound. A better approach is a moderate deficit of about 300 to 500 kcal below your TDEE, which usually stays above your BMR. If your food log shows you eating under your BMR, the usual reason is missed food (oil, chai, snacks), not real eating.
Can I increase my BMR?
A little. Muscle burns more energy at rest than fat, so strength training and enough protein nudge BMR up over months. Crash dieting does the opposite: it can lower BMR slightly as your body adapts. Walking and daily movement do not change BMR, but they raise your TDEE, which is what matters for weight loss.
How accurate is this BMR calculator?
It uses the Mifflin-St Jeor equation, the most accurate of the common formulas for most people, and can be off by 10 to 15 percent for an individual. If you enter your body fat percentage it also uses the Katch-McArdle formula, which accounts for muscle. Treat the result as a starting point and adjust after two to three weeks of real results.
Why does my BMR go down as I lose weight?
A smaller body costs less to run, so BMR falls as weight comes off. That is why a deficit that worked at the start can turn into maintenance. Recalculate roughly every five kilos lost.
Medical disclaimer: this calculator gives a general estimate using standard population formulas. It is not medical advice and cannot account for your individual health, medication or body composition. Please speak to a qualified doctor or registered dietitian before making significant changes — especially if you are pregnant, breastfeeding, under 18, or managing a health condition. See the full disclaimer.