How to calculate bmr
BMR = 10 × kg + 6.25 × cm − 5 × age + 5 (male) or − 161 (female)
Worked example. Your BMR: 1,727 calories / day.
Example inputs — Sex: Male; Age: 32; Height (inches): 70 in; Weight (lb): 170 lb. Starting values are illustrative.
Educational estimate — not medical advice.
From George Guju, founder of Calculyn · Educational calculator guidance, not professional advice.
How it works
BMR is the energy your body needs to keep you alive at complete rest. We use the Mifflin–St Jeor equation, considered one of the most accurate for most adults.
Using the bmr estimate
Basal metabolic rate describes energy used for essential bodily functions at rest. This calculator estimates resting energy from a formula rather than measuring it in a laboratory. It is helpful for distinguishing the body's baseline energy use from the additional energy associated with movement, work and exercise.
Step-by-step inputs
- Sex. Replace the starting value with your own, keeping the displayed unit and period. Starting example: Male .
- Age. Replace the starting value with your own, keeping the displayed unit and period. Starting example: 32 .
- Height (inches). Replace the starting value with your own, keeping the displayed unit and period. Starting example: 70 in.
- Weight (lb). Replace the starting value with your own, keeping the displayed unit and period. Starting example: 170 lb.
Worked example with the starting values
Using the starting inputs, the estimate is Your BMR: 1,727 calories / day.
Educational estimate — not medical advice.
Make a useful comparison
Enter your measurements in the displayed units and check them before comparing results. Formula-based resting estimates depend on the inputs, so a height or weight conversion mistake can create a much larger error than rounding.
Read the formula and assumptions on this page to understand which population model is used. Different equations can give different estimates for the same person; disagreement does not mean one calculator has directly measured your metabolism.
Use a TDEE calculation when the question is total daily energy rather than resting energy. The activity adjustment is a separate assumption, not an ingredient you should silently add to a BMR result.
Common mistakes to avoid
- BMR is not the same as a recommended food intake. Eating exactly the displayed resting estimate does not account for all activity or individual nutritional needs.
- The number does not diagnose a slow or fast metabolism. A general formula cannot evaluate symptoms, medical conditions or the effects of medication.
- Avoid treating differences of a few calories as meaningful precision. Body composition and individual variation create uncertainty well beyond the final decimal places of a computed result.
Assumptions & limitations
- Based on population formulas that may not fit athletes, pregnancy, children or medical conditions.
Formula and assumptions reviewed October 2026 by the Calculyn team. How we build our calculators
Frequently asked questions
Is BMR the same as calories I should eat?
No. Multiply BMR by an activity factor to get TDEE, your daily maintenance calories.
Is estimated BMR the same as measured metabolism?
No. The calculator applies a population equation. Clinical measurement is a different process.
Should I add an activity factor?
For estimated total daily expenditure, use the TDEE tool and its activity assumptions. Keep the resting and total-energy concepts separate.