Scientifically validated formula
BMR Calculator UK
Discover how many calories your body burns at rest using the Mifflin-St Jeor formula
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic physiological functions whilst at complete rest—think breathing, circulation, cell production, and nutrient processing. It represents the minimum energy your body requires to stay alive, accounting for roughly 60–75% of your total daily calorie expenditure.
Understanding your BMR is the foundation of any effective weight management plan. Whether you're looking to lose weight, maintain your current physique, or build muscle, knowing your BMR helps you set realistic calorie targets. Our free UK BMR calculator uses the scientifically validated Mifflin-St Jeor equation, widely regarded as the most accurate formula for the general population.
Simply enter your age, gender, height, and weight below—using Stones and Pounds, Metric, or US units—and we'll calculate your BMR instantly. For a complete picture including your Total Daily Energy Expenditure (TDEE) and personalised calorie targets for weight loss or gain, visit our full calorie calculator.
Calculate Your BMR
Find out how many calories your body burns at rest
FAQs
What is a good BMR for my age?
There's no single "good" BMR—it varies based on your gender, age, height, and weight. Generally, men have higher BMRs than women due to greater muscle mass. A typical BMR ranges from 1,200–2,000 kcal/day for women and 1,500–2,400 kcal/day for men. What matters most is using your personal BMR to set appropriate calorie targets.
Does BMR decrease with age?
Yes, BMR naturally declines with age, typically by about 1–2% per decade after age 20. This happens because we tend to lose muscle mass and gain fat as we age. Maintaining an active lifestyle and strength training can help preserve muscle mass and keep your BMR higher for longer.
What's the difference between BMR and TDEE?
BMR is your resting calorie burn, whilst TDEE (Total Daily Energy Expenditure) includes all calories burned through daily activities, exercise, and digestion. TDEE = BMR × Activity Level. For weight management, you should base your calorie targets on TDEE, not BMR. Use our full calculator to get your TDEE.
Can I eat at my BMR to lose weight?
Eating at your BMR would create a significant calorie deficit since you burn additional calories through daily activities. However, the NHS recommends a more moderate approach: eating 500–600 calories below your TDEE (not BMR) for sustainable weight loss of 0.5–1kg per week. Eating too little can slow your metabolism and make weight loss harder long-term.
Get Your Full Calorie Plan
Now that you know your BMR, calculate your Total Daily Energy Expenditure (TDEE) and get personalised calorie targets for weight loss, maintenance, or muscle gain—all aligned with NHS guidelines.
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