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Calorie Calculator

Calculate your daily calorie needs for maintenance, weight loss, or weight gain.

Last reviewed 15 August 2026Reviewed after a methodology change

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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, review maintenance, weight loss and weight gain together rather than in isolation. Then rerun the tool with one input adjusted.

How to read your results

Maintenance

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.

Weight Loss

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.

Weight Gain

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

This calorie calculator estimates your Total Daily Energy Expenditure (TDEE) by first calculating your Basal Metabolic Rate using the Mifflin-St Jeor equation, then applying an activity multiplier based on your self-reported exercise level. The result represents an approximate daily calorie intake needed to maintain your current weight. To lose weight, you would typically consume fewer calories than this figure; to gain weight, you would consume more. It is important to recognise that calorie calculators provide estimates, not precise prescriptions. Differences in digestion, food composition, and individual metabolism mean the figure shown may be higher or lower than your true requirement. Please consult a GP or registered dietitian before making significant dietary changes.

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

WHO guidance suggests 2,500 kcal for an average man and 2,000 kcal for an average woman as a maintenance estimate. Actual needs depend on age, weight, height and activity - calculated via BMR x activity factor. For weight loss a 500 kcal/day deficit produces roughly 0.5 kg loss per week; for gain a 300-500 kcal surplus supports muscle building with minimal fat gain.

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