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BMR calculator

Estimate your Basal Metabolic Rate (Mifflin-St Jeor).

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Enter Sex, Weight (kg), Height (cm), Age and the BMR calculator works out BMR (kcal/day) straight away. For instance, with Sex = Male, Weight (kg) = 70, Height (cm) = 175 and Age = 30 it returns BMR (kcal/day) = 1,649.

How to use it

  1. Enter your values: Sex, Weight (kg), Height (cm), Age.
  2. Read the result instantly: BMR (kcal/day).

Frequently asked questions

How does the BMR calculator work?

It takes Sex, Weight (kg), Height (cm) and Age and derives BMR (kcal/day) from them. The calculation is live as you type, so the result updates on every change.

Which values does the calculator ask for?

4 values: Sex, Weight (kg), Height (cm) and Age. Nothing else is required — no account, no file upload.

What does a typical calculation look like?

With Sex = Male, Weight (kg) = 70, Height (cm) = 175 and Age = 30, the calculator returns BMR (kcal/day) = 1,649. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

How much does the result change with different inputs?

It moves a lot. Using Sex = Female, Weight (kg) = 77, Height (cm) = 193 and Age = 60 instead, BMR (kcal/day) goes from 1,649 to 1,515 — which is why it is worth testing a few scenarios rather than trusting a single figure.

Which “Sex” option should I choose?

You can pick between « Male » and « Female ». Each one changes what the calculator works out, so switch and compare — the default is « Male ».

What does it give for smaller values?

Scaled down to Sex = Male, Weight (kg) = 63, Height (cm) = 158 and Age = 15, BMR (kcal/day) comes out at 1,548. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Checking one clinical number against the definition that gives it meaning: a dose against a body weight, a laboratory value corrected for the albumin or glucose that distorted it, a blood pressure against a guideline's threshold table, a heart rate or a basal metabolic rate against the formula that defines it.

What is the most common mistake?

Reading the output as a finding. Every figure here is arithmetic on numbers you typed: a correction formula measures nothing, and a threshold table classifies one reading rather than a person. Blood pressure in particular means little until it has been measured repeatedly on separate occasions, and a dose worked out here is a way of checking a prescription, never of writing one.

What is the difference between the BMR calculator and the Body surface area calculator?

This one returns BMR (kcal/day); the Body surface area calculator returns Body surface area (m²) and Du Bois (m²). That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Weight-based medication dosage calculator is the closest one after this: Turns a weight-based prescription into a concrete amount: from body weight, the dose in mg per kg and — for a liquid — the concentration in mg per ml, it works out the milligrams and millilitres per dose and the total per day. An arithmetic aid only, never a substitute for a clinician.

Further reading

All guides →
ExplainerWhat Is Your BMR? Basal Metabolic Rate ExplainedYour basal metabolic rate is the energy your body burns at complete rest. Learn how the Mifflin-St Jeor equation estimates it and what raises or lowers it.ExplainerHow Long Does Alcohol Stay in Your System?The body clears roughly one standard drink per hour. See how long alcohol stays in blood, breath and urine — and why you can't rush it.ExplainerWhat Are Pack-Years?A pack-year sums up a smoking history in one number. Here is how it is calculated and why doctors use it to judge risk and screening.ExplainerWhat Is Lean Body Mass? LBM vs Fat MassLean body mass is everything in your body that isn't fat. Learn how the Boer formula estimates it and why it matters for health and training.ComparisonBMR vs TDEE: What's the Difference?BMR is what you burn at rest; TDEE is what you burn in a whole day. Here's how they relate, how the activity multiplier works, and which to use.ExplainerHow Many Calories Are in a Pound of Fat?A pound of body fat holds about 3,500 calories. See where the number comes from, why it's a rough guide, and how to use it for weight loss.