Basal Metabolic Rate Calculator for United Kingdom
Estimate the calories your body uses at rest with the Mifflin-St Jeor equation. BMR is a baseline energy estimate, not your full daily calorie requirement.
Enter your adult age, weight and height to estimate resting energy needs.
What Is BMR?
Basal Metabolic Rate is an estimate of how much energy your body would use over 24 hours at complete rest to support essential functions such as breathing, circulation, brain activity and temperature regulation. It is not the same as the calories you normally burn in a full day because walking, working, exercise and digestion add extra energy use.
Mifflin-St Jeor equation
This calculator uses the Mifflin-St Jeor equation, a widely used predictive equation for resting energy expenditure in adults. It uses weight in kilograms, height in centimetres, age and sex-specific constants. Like every predictive equation, it can differ from a laboratory measurement.
What affects BMR?
Body size, age and sex-specific equation constants influence the estimate. Real resting metabolism can also be affected by lean mass, genetics, hormones, illness, medications, sleep, recovery and other individual factors. That is why a calculator should be used as a reference rather than a precise metabolic test.
BMR vs TDEE
BMR is the resting baseline. TDEE adds an activity multiplier to estimate your full daily energy expenditure. If your goal is to estimate how many calories you may need across a normal day, TDEE or the Calorie Calculator United Kingdom is more useful.
BMR Calculator United Kingdom: FAQs
Is BMR the number of calories I should eat?
No. BMR estimates resting energy use. Most adults burn more energy than BMR because normal living includes movement, work, exercise and digestion.
Why does BMR decrease with age in the formula?
The Mifflin-St Jeor equation includes age because average resting energy expenditure tends to change across adulthood. Individual changes vary, particularly with muscle mass and health status.
Can two people with the same weight have different BMRs?
Yes. Height, age, equation sex and body composition can differ. Even two people with similar inputs can have different measured resting metabolism because predictive equations describe population averages.
How do I turn BMR into daily calories?
Multiply BMR by an activity factor to estimate TDEE. The easiest option is to use our TDEE Calculator United Kingdom, which applies standard activity multipliers automatically.