Calorie Calculator

Fill in a few details and the calculator builds a picture of your daily energy needs.

1. Choose Sex and enter your Age (10 to 120).
2. Set Units, then enter Height (cm), or Height: feet (imperial) and Height: inches (imperial), and Weight (kg or lb).
3. Pick an Activity level, from Sedentary (desk job, little exercise) through Lightly active (1-3 days a week), Moderately active (3-5 days) and Active (6-7 days) to Very active (hard exercise or physical job).
4. Choose a Goal: maintain weight, lose 0.5 kg (1 lb) or 1 kg (2 lb) per week, or gain 0.5 kg (1 lb) per week.

The results give your basal metabolic rate (BMR), maintenance calories (TDEE), your daily target and a weekly total, plus a table of maintenance, lose and gain figures for all five activity levels.

BMR is the energy your body uses at rest. The tool applies the Mifflin-St Jeor equation: BMR = 10 x kg + 6.25 x cm - 5 x age + 5 for men, with - 161 in place of + 5 for women. Maintenance is BMR multiplied by 1.2, 1.375, 1.55, 1.725 or 1.9 for the five activity levels. The goal then adds or subtracts 500 or 1,000 kcal a day.

Worked example, a 30-year-old man of 175 cm and 70 kg: BMR = 700 + 1,093.75 - 150 + 5 = 1,649 kcal. At the moderately active level maintenance is 1,649 x 1.55, about 2,556 kcal, and the lose 0.5 kg goal gives a target of 2,056 kcal. For a 30-year-old woman of 165 cm and 60 kg, lightly active, BMR is 1,320 kcal and maintenance 1,815 kcal.

The 500 kcal figure comes from a rule of thumb that about 7,700 kcal equals one kilogram of body fat, so 500 kcal a day over a week is roughly 0.45 kg. Real results drift from this as the body adapts.

Maintenance is the intake at which your weight should stay roughly stable.

• Treat it as a starting point. Individual metabolism differs by around 10 percent, so weigh yourself for two or three weeks and adjust by 100 to 200 kcal if the trend is off.
• Be honest about activity. This is the biggest guess in the sum, and most people overestimate it; when unsure, pick the lower level.
• Check the warning. If the target falls below about 1,200 kcal, the tool says so. It still shows the number, so the warning is yours to heed.

The table under the main result is handy when you are torn between two activity levels. For the 70 kg man in the example, choosing Active instead of Moderately active raises maintenance from 2,556 to 2,844 kcal, a gap of 288 kcal a day that outweighs most of the other uncertainty. The lose and gain columns in that table always use 500 kcal, whatever Goal you picked, and the Weekly target row is simply your daily target times seven. Recalculate after a large change in weight, since a lighter body needs fewer calories, and again if your routine changes from a desk job to a physical one. Imperial users can enter pounds and feet and inches; the tool converts them to kilograms and centimetres before applying the equation, so the answer is the same either way.

The equation is meant for healthy adults. It does not account for pregnancy, breastfeeding, medical conditions or very high muscle mass. These are general estimates and not medical advice; speak to a doctor or registered dietitian before changing your diet. To turn a calorie target into grams of protein, carbohydrate and fat, use the macro calculator; to move between kcal and kJ, use the energy converter. You can also see where your weight sits with the BMI calculator or estimate body composition with the body fat calculator.