How it works
How BMR Calculator solves the problem
Use this BMR Calculator when you need a BMR calculator you can trust — clean inputs, transparent steps, zero fluff.
The people who ship BMR Calculator are the same ones who had to look up a BMR calculator on deadline and hated the result. This is the version they wanted to find.
Trend it weekly; obsessing over a single day is the fastest way to burn out. Weigh yourself at the same time on the same scale — then work out the numbers and the rest of this page explains what the answer means.
Mifflin-St Jeor equation estimates calories burned at complete rest. Multiply by an activity factor (1.2 sedentary to 1.9 very active) to get TDEE.
On this page you will see British Nutrition Foundation, Nutrition & Fitness and NHS treated as first-class terms — each one is linked to the calculators and references that use it, so you can follow the thread without retyping queries into a search bar.
The formula we run is BMR = 10×kg + 6.25×cm − 5×age + 5 (men) / −161 (women). You'll see each term laid out in the worked example below.
If it helps, jump straight to the Nutrition hub or compare with the BMI Calculator and the TDEE Calculator — those two calcs are the ones readers usually open right after this page.
Seeing it on real numbers
A working example keeps the formula honest:
Mifflin-St Jeor equation estimates calories burned at complete rest. Multiply by an activity factor (1.2 sedentary to 1.9 very active) to get TDEE.
Every run comes back to BMR = 10×kg + 6.25×cm − 5×age + 5 (men) / −161 (women) — change the inputs, the structure of the answer stays.
When to use this calculadora
BMR Calculator is aimed at people arriving with questions like these:
- "BMR formula"
- "Mifflin St Jeor equation"
- "BMR vs TDEE"
- "What is bmr calculator"
- "How to calculate bmr calculator"
- "Bmr calculator formula"
When to reach for something else
Every tool has an edge where it stops being the right answer. BMR Calculator is no exception:
- For legally binding tax or medical decisions — cross-check with HMRC, NHS or a qualified professional.
- For very large or very small extremes the rounding error outgrows the useful precision.
- When the underlying rate or threshold has changed since the page was last reviewed — always verify with the primary source.
- When the input you have is already a derived figure (net of something) — feeding it in as "gross" will double-subtract.
What goes wrong nine times out of ten
Every time you work out the numbers for a new scenario, one of these creeps in — it's worth knowing them ahead of time.
- Ignoring the unit multiplier (k, M, %, basis points) on the input and feeding the raw number in anyway.
- Assuming the default settings match your context — check the calc's assumptions box before trusting the figure.
- Re-entering the result of a previous step as an input without keeping the full-precision number in front of you.
- Reading a negative answer as an error when the maths is telling you the inputs are in the wrong order.
- Cross-comparing to a tool that uses a different formula family (e.g. Mifflin vs Harris-Benedict) without saying so.
The sources behind the numbers
Where the maths needs an external authority, we cross-check against:
- NHS
- British Nutrition Foundation
Works well alongside
If this question keeps coming up for you, the same cluster of tools usually comes next:
- BMI Calculator — Check your Body Mass Index in metric or imperial, with NHS weight categories explained.
- TDEE Calculator — Work out Total Daily Energy Expenditure based on BMR and activity level to set a calorie target.
- Macronutrient Calculator — Split your daily calories into protein, carbs and fat in grams, based on your body weight and training goal.
How we keep this accurate
Our calculadoras run on pure, unit-tested functions — the same logic lives in the browser and in the CI test suite. When tax rates, thresholds or official figures move, the update lands within 24 hours of the announcement. You can read the editorial policy and corrections policy.
Found an out-of-date number on BMR Calculator or anywhere else in the Nutrition toolkit? Send it to the editorial desk and we'll patch it. Or browse the full calculadora directory for the next tool you need.