Calorie Calculator

Estimate resting energy use and daily maintenance calories with the Mifflin–St Jeor equation. For adults; activity factors are approximate rather than measurements.

Calorie Calculator

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Guide updated 6 October 2026

How to estimate daily maintenance calories

Select metric or imperial units, enter your age, weight and height, and choose the sex term used in the equation. With imperial units, height is entered as total inches rather than feet and inches; five feet ten inches is 70 inches.

Choose an activity factor and confirm that the adult-use conditions apply. The result shows estimated resting energy, daily maintenance energy and its kilojoule equivalent. This version does not prescribe a weight-loss target, meal plan or macro allocation.

Mifflin–St Jeor equation and the meaning of resting energy

The simplified male equation is 10 × weight in kg + 6.25 × height in cm − 5 × age + 5. The female equation uses the same first three terms and subtracts 161 instead of adding 5. The original study was published in 1990 and measured resting expenditure in healthy adults.

The result estimates resting energy expenditure, often loosely called BMR in online tools. It is not a measurement of your metabolism, and it is not the same as total daily calorie needs. This equation uses two sex-specific constants; it cannot personalize hormone treatment, body composition or every individual physiology.

Activity factors and total daily energy expenditure

Maintenance estimate = resting energy × selected activity factor. The form offers 1.2, 1.375, 1.55, 1.725 and 1.9 as broad activity assumptions. Movement at work and throughout the day matters as well as planned exercise.

These factors are not part of a laboratory measurement and their labels are approximate. If you are uncertain between two levels, compare both results rather than assuming a precise daily burn. Avoid counting exercise twice by adding tracker calories to an estimate that already includes your activity.

Calorie calculation example and unit conversion

For a fictional 35-year-old using the male equation, weighing 75 kg and measuring 175 cm, estimated resting energy is 1,673.75 kcal/day. At factor 1.375, maintenance is approximately 2,301 kcal/day. The example demonstrates the formula, not an intake recommendation.

The tool converts pounds to kilograms using 0.45359237 and inches to centimetres using 2.54. One dietary Calorie is one kilocalorie, abbreviated kcal; one kcal equals 4.184 kilojoules. The displayed results are rounded to whole units.

Who should not use this estimate as a diet plan?

The tool is restricted to adults and is not designed for pregnancy, breastfeeding, children or a medical nutrition plan. It uses input limits of age 18–100, weight 30–300 kg and height 120–230 cm as software boundaries, not as definitions of healthy measurements.

Medical conditions, medication, athletic training and differences in body composition can change energy needs. If you need a clinical intake target, discuss your circumstances with a qualified professional. This estimate alone cannot establish a safe calorie deficit.

Why calorie calculators give different answers

Different equations, activity multipliers, rounding and unit handling produce different outputs. The biggest practical uncertainty is often the activity assumption. A wearable’s daily expenditure estimate can also use a different method.

Check kg versus pounds, centimetres versus total inches, and the selected equation term before comparing results. A maintenance estimate is a starting reference for understanding energy needs, not a promise about weight change.