How to use the Calorie calculator
- 1Enter your age, sex, height and weight.
- 2Choose the activity level that best matches a typical week, from sedentary to extremely active.
- 3Read your BMR and your maintenance calories (TDEE).
- 4Use the targets for losing or gaining weight at two paces: 250 or 500 kcal a day below or above maintenance. Heed the caution if a target falls very low.
How it works
BMR is calculated with the Mifflin–St Jeor equation, which uses weight, height, age and sex. It is widely used by dietitians and generally considered one of the more reliable equations for healthy adults, but it remains an estimate: two people with identical inputs can differ by a few hundred calories.
TDEE multiplies BMR by an activity factor: 1.2 for sedentary, 1.375 for light activity, 1.55 for moderate, 1.725 for very active and 1.9 for extremely active. Most people overestimate their activity, so if you're unsure, choose the lower option.
Weight-change targets subtract or add 250 or 500 kcal a day. Treat them as starting points: track your weight for a few weeks and adjust, because real-world energy needs shift as your weight and activity change.
Formulas
BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + s- s
- +5 for men, −161 for women
TDEE = BMR × activity factorFactors: 1.2, 1.375, 1.55, 1.725 or 1.9.
Worked examples
Man, 30, 80 kg, 180 cm, moderately active
- 1BMR = 10 × 80 + 6.25 × 180 − 5 × 30 + 5
- 2= 800 + 1,125 − 150 + 5 = 1,780 kcal
- 3TDEE = 1,780 × 1.55 = 2,759 kcal
- 4Moderate loss target: 2,759 − 500 = 2,259 kcal
About 2,759 kcal to maintain, or about 2,259 kcal for steady weight loss.
Woman, 45, 65 kg, 165 cm, lightly active
- 1BMR = 10 × 65 + 6.25 × 165 − 5 × 45 − 161
- 2= 650 + 1,031.25 − 225 − 161 = 1,295.25 kcal
- 3TDEE = 1,295.25 × 1.375 ≈ 1,781 kcal
- 4Gentle loss target: 1,781 − 250 = 1,531 kcal
About 1,781 kcal to maintain, or about 1,531 kcal for gradual loss.
What is the difference between BMR and TDEE?
BMR is the energy you would burn lying at rest all day: breathing, circulation, keeping warm. TDEE adds everything else, including walking, work, exercise and digesting food. You should generally eat around your TDEE to maintain weight, and not routinely below your BMR without professional guidance.
How much of a calorie deficit is safe?
A deficit of 250 to 500 kcal a day is a common, moderate starting point that many people can sustain. Much larger deficits can make it hard to get enough protein, vitamins and minerals, and are harder to stick to. If a target comes out very low, as it can for smaller or less active people, the calculator shows a caution; speak to a doctor or registered dietitian before going lower.
Frequently asked questions
Which activity level should I pick?
Sedentary means a desk job with little exercise; light is exercise 1–3 days a week; moderate is 3–5 days; very active is hard exercise 6–7 days; extremely active is physical work plus training. Choose the lower level if you're between two.
How accurate is the Mifflin–St Jeor equation?
It is a well-established estimate for adults, but it can't account for body composition, genetics or medical conditions. Use it as a starting figure and adjust based on how your weight changes over several weeks.
Why does the calculator ask for sex?
The equation has different constants for men (+5) and women (−161) because, on average, men have more lean mass at the same weight and height, which burns more energy.
Will eating 500 kcal less every day always mean steady weight loss?
Not exactly. As you lose weight your energy needs fall, and water weight can mask fat loss in the short term. Recalculate after significant weight changes.
Is this suitable during pregnancy or for teenagers?
No. Energy needs during pregnancy, breastfeeding and adolescence differ from these adult estimates, so get advice from a healthcare professional.