BMR Calculator
Work out your Basal Metabolic Rate — the calories your body burns at complete rest — using the trusted Mifflin-St Jeor equation, then see your daily maintenance calories.
BMR calculator
Mifflin-St Jeor. Metric or imperial.
A guide only, not medical or nutrition advice. For personalised support see the NHS healthy weight pages.
What is Basal Metabolic Rate?
Your Basal Metabolic Rate (BMR) is the number of calories your body needs just to keep you alive at complete rest — powering your heart, brain, breathing and cells. It's the single biggest part of your daily energy use, typically 60–70% of the total. Multiply BMR by an activity factor and you get your maintenance calories (TDEE): the calories to stay the same weight.
This calculator uses the Mifflin-St Jeor equation, the most accurate widely-used formula. For a 35-year-old man, 175 cm and 75 kg, BMR is about 1,674 calories a day. At a moderate activity level that's roughly 2,594 maintenance calories.
The Mifflin-St Jeor equation
| Sex | BMR formula |
|---|---|
| Men | (10 × kg) + (6.25 × cm) − (5 × age) + 5 |
| Women | (10 × kg) + (6.25 × cm) − (5 × age) − 161 |
Source: Mifflin MD, St Jeor ST et al. (1990), the basis of most modern calorie tools. NHS guidance on calories: NHS — understanding calories.
From BMR to a calorie target
Maintenance calories are your BMR × activity factor. To lose weight, the NHS suggests a deficit of about 500–600 calories a day below maintenance, aiming for roughly 1,900 (men) or 1,400 (women) as common starting targets. To gain, add a modest surplus. Pair this with our calorie calculator and BMI calculator for a fuller picture.
Frequently asked questions
How is BMR calculated?
This calculator uses the Mifflin-St Jeor equation: for men, BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5; for women the final figure is −161 instead of +5. It is widely regarded as the most accurate everyday formula.
What is the difference between BMR and maintenance calories?
BMR is the energy you burn at complete rest. Maintenance calories (TDEE) is your BMR multiplied by an activity factor to account for movement and exercise — it's the number of calories to stay the same weight.
How many calories should I eat to lose weight?
The NHS suggests eating about 500–600 calories a day below your maintenance level for steady weight loss, often around 1,900 for men and 1,400 for women. Always keep changes sensible and seek advice if unsure.
Is Mifflin-St Jeor accurate?
It is one of the most accurate formulas for estimating BMR in the general population and is used by clinicians and reputable fitness tools. It is still an estimate — individual metabolism varies — so treat the result as a starting point.
Does muscle increase my BMR?
Yes. Muscle is more metabolically active than fat, so people with more muscle tend to have a higher BMR. The Mifflin-St Jeor formula uses total weight, so very muscular people may find their true BMR is a little higher.