Health and Fitness Calculators
Basal Metabolic Rate (BMR)
Your basal metabolic rate is the energy your body uses doing nothing at all: breathing, pumping blood, keeping your temperature up and repairing itself. It is the floor under everything else you burn in a day.
Your basal metabolic rate is about 0 calories a day.
How it works
This uses the Mifflin-St Jeor equation, published in 1990, which is the one most dietitians reach for because it was derived on a modern population and predicts measured resting energy better than the older Harris-Benedict equation does.
Men: BMR = 10 × weight in kg + 6.25 × height in cm - 5 × age + 5
Women: BMR = 10 × weight in kg + 6.25 × height in cm - 5 × age - 161
A 35-year-old woman, 165 cm tall, weighing 65 kg: (10 × 65) + (6.25 × 165) - (5 × 35) - 161, which is 650 + 1031 - 175 - 161, or about 1345 calories a day.
What this number is not
It is not what you should eat. Basal metabolic rate counts the energy you would use lying still all day, and nobody does that, so eating to this number means eating well under what you spend. The number you want for that is your total daily energy expenditure.
How accurate it is
Mifflin-St Jeor lands within ten percent of a measured resting energy for most people, and further out at the extremes of body composition. It takes no account of muscle, so a very muscular or a very lean person is better served by an equation that uses lean body mass.
Common questions
Is basal metabolic rate the same as resting metabolic rate?
They are close enough to be used interchangeably in everyday use. Strictly, basal rate is measured after a night of fasting and complete rest, and resting rate is measured under less exacting conditions and comes out a few percent higher.
Does FitnessSyncer store my BMR?
Yes, your profile holds a basal metabolic rate and the rest of the product reads it. Working it out here and putting it in your profile means your reports use the same figure.
Why does my number differ from another site?
Almost always because the other site uses the Harris-Benedict or the Katch-McArdle equation rather than Mifflin-St Jeor. All three are reasonable and they disagree by around a hundred calories, which is a useful reminder of how approximate any of them is.
