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Calorie Calculator

Turn a basal metabolic rate into a daily calorie target using an activity multiplier.

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What Calorie Calculator does

Total daily energy expenditure is basal metabolic rate multiplied by an activity factor. The multiplier accounts for everything from deliberate exercise to fidgeting and standing up.

This calculator takes a BMR figure you already have and applies the standard multipliers, then shows targets for maintaining, losing and gaining weight.

  • Standard activity multipliers from sedentary to extremely active
  • Maintenance calories, plus a 500 kcal deficit and surplus

How to use Calorie Calculator

  1. 1

    Get your BMR first

    Use the BMR calculator, then enter the figure here. This tool does not calculate it for you.

  2. 2

    Choose an activity level honestly

    This is where most estimates go wrong. Moderately active means consistent structured exercise several times a week, not an ordinary day with some walking.

  3. 3

    Read the three targets

    A 500 kcal daily deficit corresponds to roughly half a kilogram of weight change per week in theory.

Limits and known behaviour

  • You must supply your own BMR; this tool applies the multiplier only.
  • Activity multipliers are broad averages. Two people who both describe themselves as moderately active can differ by several hundred calories a day.
  • Self-reported activity is systematically overestimated and food intake systematically underestimated, in studies of the general population as well as of trained observers.
  • The rule that 3500 kcal equals half a kilogram of fat is an approximation that holds early in a deficit and becomes less accurate as the body adapts and weight falls.
  • Very low calorie targets can be unsafe and should not be undertaken without medical supervision.
  • This is an estimate from a published formula, not a medical assessment. It cannot diagnose anything, and it is no substitute for advice from a clinician who knows your history.

Privacy and data handling

Runs entirely in your browser

  • Every figure you enter stays in this page. Your metabolic and activity figures is not transmitted, logged or stored anywhere.
  • There is no account, no saved history and no autosave: reloading the page clears the form.

Site-wide data handling, including analytics and advertising, is described in the privacy policy.

Frequently asked questions

Why is my figure different from my fitness tracker's?

A tracker estimates energy actually expended from heart rate and movement. This applies a fixed multiplier to a resting estimate. They answer different questions with different data and will not agree.

Which activity level should I choose?

Choose one lower than you think. Research consistently finds people overestimate their activity. If your weight does not move over several weeks, the multiplier was wrong rather than the arithmetic.

Why did my weight loss stall?

Energy needs fall as body weight falls, so a deficit that worked at the start becomes maintenance later. Recalculate periodically as your weight changes.