Daily Calorie Needs Calculator

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Daily Calorie Needs Calculator

This calculator estimates resting energy expenditure with the Mifflin–St Jeor equation, then applies an activity factor to estimate total daily needs. Enter your age, sex, height, weight and usual activity level.

Predictive equations provide estimates, not prescriptions. Real needs can differ from the estimate by several hundred kilocalories a day. People who are pregnant or breastfeeding, living with eating disorders, or managing medical conditions need individualised targets from a qualified professional.

Daily calorie needs calculator

Estimated resting energy and daily needs using the Mifflin–St Jeor equation.

Required by the Mifflin–St Jeor equation.
years
Units
centimetres
kilograms
inches
pounds

Nothing you enter is stored. Results are computed on request and discarded.

Methodology & references

Resting energy expenditure uses the Mifflin–St Jeor equation (1990): REE = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5 for men or − 161 for women. Total daily needs multiply REE by a standard activity factor (1.2 sedentary up to 1.9 for athletes). The equation estimates group averages; individual needs can differ substantially.

References

Limitations

  • Mifflin–St Jeor was validated in adults; it is not reliable during pregnancy, breastfeeding, childhood, critical illness, or for athletes with very high muscle mass.
  • The result is an estimate for maintenance — not a target for weight gain or loss without professional guidance.
  • Very restrictive diets carry real health risks and should only be followed under medical supervision.

How to use this calculator

  • Enter your age, sex, height and weight.
  • Choose the activity level that best matches a typical week.
  • Press Calculate. Read your resting energy and total daily estimate separately.
  • Read the limitations section before using the number to plan a diet.

Understanding your result

Resting energy expenditure (REE) is what your body uses at complete rest; total daily needs are REE multiplied by an activity factor. Showing both lets you see how much of the estimate depends on how active you are.

If you plan to change your intake to manage weight, aim for gradual change (commonly about 0.25 to 0.5 kg per week), avoid extreme restriction, and involve a qualified professional — especially if you have any medical condition.

Methodology & references

Resting energy expenditure uses the Mifflin–St Jeor equation (1990): REE = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5 for men or − 161 for women. Total daily needs multiply REE by a standard activity factor (1.2 sedentary up to 1.9 for athletes). The equation estimates group averages; individual needs can differ substantially.

Limitations

  • Mifflin–St Jeor was validated in adults; it is not reliable during pregnancy, breastfeeding, childhood, critical illness, or for athletes with very high muscle mass.
  • The result is an estimate for maintenance — not a target for weight gain or loss without professional guidance.
  • Very restrictive diets carry real health risks and should only be followed under medical supervision.

Frequently asked questions

How accurate are calorie calculators?

Predictive equations are estimates that can differ from measured energy needs by several hundred kilocalories a day. Treat the result as a rough planning figure, not a precise prescription.

How quickly should I try to lose or gain weight?

For most adults a change of about 0.25 to 0.5 kg per week is considered gradual and more sustainable. Very restrictive diets can be harmful and are not advised without medical supervision. Pregnant or breastfeeding women and people with eating disorders or medical conditions need individualised advice.

Why does the calculator show resting energy separately?

Resting energy is what your body uses at complete rest, and total needs are that figure multiplied by an activity factor. Showing both separately makes the assumptions transparent instead of hiding them in a single number.

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