Skip to content

Calorie Calculator

Estimate how many calories you need each day to maintain your weight, and how to eat to lose or gain weight at a safe pace.

Formulas last reviewed: September 2026

Disclaimer: Results are general estimates for information and education only. They are not medical advice, a diagnosis or a treatment plan. Please talk to a doctor or qualified health professional before making health, diet, exercise or pregnancy decisions.

What is a calorie calculator?

Your body burns calories every day just to stay alive, and more when you move. A calorie calculator estimates that daily total and shows how many calories to eat to maintain, lose or gain weight.

It first finds your basal metabolic rate (BMR) from age, sex, height and weight, then multiplies it by an activity factor to get your total daily energy expenditure.

How it is calculated

BMR (Mifflin-St Jeor) = 10 × kg + 6.25 × cm − 5 × age + 5 (men) or − 161 (women)
Maintenance calories = BMR × activity factor (1.2 to 1.9)

About 7,700 kcal equals 1 kg of body fat, so eating 500 kcal less each day leads to roughly 0.45 kg of fat loss a week.

Worked example

Man, 30 years, 170 cm, 70 kg, lightly active

BMR
1,618 kcal
Activity factor
× 1.375
Maintenance
2,224 kcal
To lose ~0.5 kg/week
1,724 kcal

Eating safely for weight change

  • Do not go below about 1,500 kcal (men) or 1,200 kcal (women) without medical supervision.
  • Aim for a gap of 250 to 500 kcal a day; bigger cuts make you lose muscle and feel weak.
  • Include enough protein and fibre — dal, eggs, curd, vegetables and whole grains keep you full.
  • Recalculate every few kilograms, because your needs fall as your weight falls.

These are estimates. Pregnant or breastfeeding women, children and people with medical conditions need personal advice from a doctor or dietitian.

Frequently asked questions

Which formula does this use?

By default the Mifflin-St Jeor equation, which is the most accurate for most people. You can also choose Harris-Benedict, or Katch-McArdle if you know your body fat percentage.

How do I pick my activity level?

Choose based on a typical week, not your best week. Most desk workers who exercise a few times a week are 'lightly active'. Overestimating is the most common mistake.

Why am I not losing weight at my calorie target?

Food portions are often underestimated, weekend eating adds up, and your needs shrink as you lose weight. Track intake honestly for two weeks and adjust by 100 to 200 kcal.

Do calories from all foods count the same?

For weight change, yes — but food quality affects hunger, energy and health. Protein and fibre keep you fuller than refined flour or sugar for the same calories.