UK weight-loss calculator
BMR calculator
Estimate your basal metabolic rate, the energy your body uses at complete rest, before you move at all.
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I’m , , cm tall, and I weigh st lb.
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Enter your details to see your estimated basal metabolic rate, the energy your body uses at rest.
What does my BMR mean?
Your basal metabolic rate is the energy your body would use over 24 hours doing nothing at all, keeping your heart beating, your lungs working, your brain running and your body at temperature. For most people it accounts for the majority of daily energy use.
It is not a target. Eating at your BMR would leave you well short of what you actually need, because it excludes every calorie you burn moving around. To find that figure, use the TDEE calculator.
BMR is mostly driven by how much you weigh and how much of that is lean tissue. It falls as you lose weight and it declines gradually with age.
How is BMR calculated?
This calculator uses the Mifflin-St Jeor equation[American Journal of Clinical Nutrition], which is widely used because it needs only height, weight, age and sex, no body-fat measurement.
BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161Sex appears in the equation because, on average, men carry more lean tissue at a given height and weight, and lean tissue is more metabolically active. The equation was derived from measurements across a population, so it captures that average difference rather than anything about an individual.
Limitations
This is a population equation, and individuals vary around it considerably. Two people matched on every input can have genuinely different resting metabolic rates.
- It does not know your body composition. Someone with much more muscle than average will be underestimated.
- It was developed largely in adults of typical build, and is less reliable at the extremes of weight.
- Thyroid conditions and some medications meaningfully change resting metabolism, and no equation accounts for that.
- Measuring BMR properly requires indirect calorimetry in a clinical setting. Everything else, including this, is an estimate.
Related calculators
Frequently asked questions
Is BMR the same as my daily calorie needs?
No. BMR is only the resting portion. Your total daily needs are higher, typically between 1.2 and 1.9 times your BMR depending on how active you are. The TDEE calculator applies that multiplier for you.
Should I eat below my BMR to lose weight faster?
It is not something we would suggest. Very low intakes make it hard to get adequate nutrition, are difficult to sustain, and are associated with loss of lean tissue alongside fat. The calculators on this site will not recommend an intake below your estimated BMR.
Very low calorie diets do have a place in some clinical situations, but they are medically supervised for good reason.
Why does my BMR go down when I lose weight?
Because there is less of you to maintain. Every kilogram lost reduces the equation by about 10 kcal a day. Over a two-stone loss that is a meaningful change, and it is one reason weight loss tends to slow down over time rather than continuing at a constant rate.
Sources
- A new predictive equation for resting energy expenditure in healthy individuals, American Journal of Clinical Nutrition
Important information
The calculators on this site provide general information and estimates. They are not medical advice and they do not diagnose any condition.
Everyone is different, and individual energy needs vary for reasons these equations cannot capture. If you have a health condition, take medication, are pregnant or breastfeeding, or have any concerns about your weight, speak to your GP, pharmacist or a registered dietitian.