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BMR Calculator

Calculate your Basal Metabolic Rate to find the calories needed at rest each day. Use BMR to set a calorie target for weight loss, maintenance or muscle gain.

Last reviewed 15 August 2026Reviewed after a methodology change

Your details

Calculator inputs

When to use this calculator

  • Before setting a new health goal or checking whether a plan is realistic.
  • When you want a quick baseline before discussing the result with a professional.
  • When you are starting a fitness or diet programme and want a starting measurement.
  • When you want to recheck the numbers after several weeks of change.

A realistic planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

A realistic planning example
InputValue
Weight (kg)80 kg
Height (cm)178 cm
Age35
Sex (1=Male, 0=Female)1

After entering these figures, focus on bmr first and then rerun the tool with a more cautious assumption.

How to read your results

BMR

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Method & assumptionsAuthoritative sources

Basal Metabolic Rate (BMR) represents the minimum number of calories your body requires to sustain essential life functions — heartbeat, respiration, temperature regulation, and cell production — while at complete rest. This calculator uses the Mifflin-St Jeor equation, which is currently recommended as the most accurate predictive equation for most adults. The formula accounts for your sex, weight, height, and age. It is worth understanding that BMR is an estimate based on averages, and individual metabolic rates can differ meaningfully due to factors including thyroid function, gut microbiome, lean muscle mass, and genetics. Your BMR result is a useful planning figure, but it should not replace personalised guidance from a healthcare professional.

Common mistakes

  • !Using an assumption that is not supported by a current local quote, bill, statement or official source.
  • !Treating a generic estimate as a lender, provider, payroll or tax authority decision.
  • !Mixing monthly and annual inputs without converting them consistently.
  • !Testing only one scenario instead of checking how a cautious assumption changes the result.

What to do next

  • Run a second scenario with a cautious assumption so you can see the downside clearly.
  • Compare the result with the related calculators below before making a decision.
  • Check current local rules, eligibility and provider terms before applying or committing money.
  • Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.

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Frequently asked

Basal Metabolic Rate is the number of calories your body uses at complete rest to maintain core functions like breathing, circulation, and cell production. It typically accounts for 60-70% of daily calorie burn in sedentary adults. BMR declines with age at roughly 1-2% per decade after 20, mostly due to lean-mass loss.

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