BMR Calculator
Estimate the calories you burn at complete rest.
Calculate your Basal Metabolic Rate (BMR) — the calories your body burns at rest — using the Mifflin-St Jeor equation. Enter weight, height, age and gender in metric or US units. The starting point for working out your daily calorie needs. Runs fully in your browser — nothing is uploaded.
How to use BMR Calculator
Choose units
Pick metric (kg / cm) or US (lb / ft) in the free online BMR Calculator so you can enter weight and height in your preferred measurement system.
Select gender
Choose male or female, since the Mifflin-St Jeor equation this BMR Calculator uses adds 5 for men and subtracts 161 for women in its formula.
Enter your stats
Type your weight, height and age, with decimals like 71.25 kg fully supported, so the calculator can compute your basal metabolic rate accurately.
Pick activity level
Select your activity from sedentary to very active to instantly convert BMR into TDEE, your total daily energy expenditure including movement and exercise.
Read calorie needs
View your BMR, a donut split of resting versus activity burn, and daily calorie targets to maintain, lose or gain weight, all updating instantly.
Share or reset
Share your BMR and calorie results via a link or reset to recalculate for new stats, helping plan diet and fitness goals free in your browser.
Frequently asked questions
What is BMR?
Basal Metabolic Rate is the number of calories your body uses at rest to power essential functions like breathing, circulation and cell production. It’s the biggest part of your daily calorie burn.
BMR vs TDEE — what’s the difference?
BMR is calories burned at rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor to include movement and exercise — that’s what you actually eat to maintain weight.
Which equation does this use?
The Mifflin-St Jeor equation, which research has found to be more accurate for most people than the older Harris-Benedict formula.
How do I calculate my BMR and daily calorie needs?
Enter your weight, height, age and gender, then pick an activity level. This free BMR calculator uses the Mifflin-St Jeor equation to find your basal metabolic rate, then multiplies it by your activity factor to estimate your daily calorie needs (TDEE) to maintain, lose or gain weight.
How many calories should I eat to lose weight?
To lose about ½ kg per week, eat roughly 500 calories per day below your TDEE — the “Lose ½ kg / week” figure this calculator shows. Don’t drop below your BMR for long, as that’s the minimum your body needs at rest.
Should I eat at my BMR to lose weight?
No — eating exactly at your BMR is too low, because BMR is only the calories you burn at complete rest. Base weight loss on your TDEE (BMR × activity) minus a moderate deficit of about 500 calories, and don't drop below your BMR for long.
Does BMR change with age?
Yes. BMR gradually declines with age as muscle mass tends to fall, which is why the Mifflin-St Jeor equation includes age. Building and keeping muscle through resistance training helps offset the drop, keeping your metabolism higher.
Is my data sent anywhere?
No. Everything is calculated in your browser with JavaScript — nothing you enter is uploaded.
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