BMR Calculator
Your Basal Metabolic Rate is the energy you would burn lying still all day – keeping your heart, brain and cells running. It is 60-75% of most people’s total daily burn. This calculator uses the Mifflin-St Jeor equation, the one dietitians reach for first, then lets you scale up to a full daily figure.
The equation
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
A 35-year-old man of 80 kg and 178 cm: 800 + 1112 − 175 + 5 = 1,742 calories a day at rest.
From BMR to daily calories (TDEE)
| Activity level | Multiply BMR by |
|---|---|
| Sedentary (desk job, little exercise) | 1.2 |
| Lightly active (1-3 days/week) | 1.375 |
| Moderately active (3-5 days/week) | 1.55 |
| Very active (6-7 days/week) | 1.725 |
| Extra active (hard training or manual job) | 1.9 |
Using the number sensibly
TDEE is an estimate with a real margin of error – individual metabolisms vary by 200 calories or more at the same size. To lose weight, a common starting point is 300-500 calories below TDEE, then adjust based on what the scale actually does over a few weeks. The equation needs weight in kilograms and height in centimetres; convert with pounds to kg and inches to cm if you think in imperial. For the height-to-weight ratio itself, see the BMI calculator.
FAQ
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor, and is your actual daily calorie burn.
Which BMR formula is most accurate?
Mifflin-St Jeor is the current standard for healthy adults. The older Harris-Benedict tends to run about 5% high. Katch-McArdle is better for very lean, athletic people but needs a body-fat figure.
How many calories should I eat to lose weight?
A common guideline is 500 below your TDEE per day, roughly 0.45 kg (1 lb) of loss per week. Results vary - adjust to what actually happens over a few weeks.
Does BMR change with age?
Yes, it declines gradually - the equation subtracts 5 calories per year of age for men. Loss of muscle mass is the main driver, which resistance training can slow.