BMR Calculator: How Many Calories You Burn at Rest
Before you plan any diet, it helps to know your baseline burn. Your BMR is the floor your total daily calories are built on.
What is the BMR Calculator?
Your Basal Metabolic Rate (BMR) is roughly how many calories your body would burn in a day if you did nothing at all — just breathing, keeping warm, and keeping your organs running. This tool uses the Mifflin-St Jeor formula, which combines weight, height, age, and sex. The result is general information only, not medical advice, and real energy needs vary with muscle mass, hormones, and health conditions.
How to use it
- Enter your weight in kilograms and height in centimetres.
- Enter your age and select Male or Female.
- Read your estimated daily calories at rest.
Worked example
A 30-year-old man weighing 70 kg at 175 cm has a BMR of 1,648.75 calories per day (700 + 1,093.75 − 150 + 5).
What is BMR and why does it matter?
BMR is the energy your body needs to stay alive at complete rest. Knowing it gives you a sensible starting point for calorie planning: eat well below it for long periods and you risk fatigue and nutrient shortfalls, while eating far above it without activity tends to add weight. Pair BMR with an activity factor to estimate your full daily needs.
Frequently asked questions
Is BMR the same as total daily calories?
No — BMR covers rest only. Your total daily burn is higher because it also includes movement, digestion, and exercise.
Why does sex change the result?
The Mifflin-St Jeor equation adds a small constant for men and subtracts one for women, reflecting average differences in body composition.