BMR calculator

BMR uses the Mifflin-St Jeor equation, which has the best accuracy record of the common predictive equations for healthy adults in a systematic review by the Academy of Nutrition and Dietetics. If you enter body fat, we switch to Katch-McArdle, which works from lean mass instead.

Daily energy is BMR multiplied by a physical activity level (PAL). Researchers describe lifestyles using PAL, and the FAO, WHO and UN University expert report groups them into sedentary, active and vigorous bands. Here we build your PAL from two parts, your work day and your exercise, then add them.

These values are our own simplified model, set inside the published PAL ranges. They are a sound starting point, not a measurement. Real needs can differ by 10 percent or more between two people with the same inputs.

Losing or gaining about 0.25 kg a week needs roughly 250 kcal (1,050 kJ) a day below or above maintenance, and about 0.5 kg needs 500 kcal (2,100 kJ). This uses the common rule of thumb of about 7,700 kcal per kilogram of body weight, which is approximate and overestimates loss over time as your body adapts.

We never set a target below your BMR, or below 1,500 kcal (men) or 1,200 kcal (women). If your goal would go lower, we hold it at that floor. Eating less than this should only be done with a doctor or dietitian.

This calculator is for healthy adults. It is not suitable if you are pregnant or breastfeeding, under 18, living with an eating disorder, or managing a medical condition that affects metabolism such as thyroid disease or diabetes. Speak with your GP or an accredited practising dietitian instead.

Mifflin et al. (1990), A new predictive equation for resting energy expenditure

Frankenfield et al. (2005), Comparison of predictive equations for resting metabolic rate

FAO/WHO/UNU, Human energy requirements