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Calorie Calculator – How Many Calories Do I Need a Day?

Find out how many calories your body uses each day and how many to eat to maintain, lose or gain weight. Enter your sex, age, height, weight and activity level in metric or US units; the calculator uses the Mifflin-St Jeor equation recommended by dietitians.

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How to use the calorie calculator

  1. Choose metric (cm, kg) or US units (feet, inches, pounds). Visitors in the US see US units first.
  2. Select your sex and enter your age.
  3. Enter your height and weight.
  4. Choose the activity level that best describes a normal week.

You’ll see the calories you need to maintain your weight, your BMR and a table of daily calorie targets to lose or gain 0.25, 0.5 or 1 kg a week.

How the calories are calculated

First your basal metabolic rate (BMR) — the energy you use at complete rest — is calculated with the Mifflin-St Jeor equation:

Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

Then BMR is multiplied by an activity factor to give your daily total:

Activity levelMultiplier
Sedentary1.2
Light exercise 1–3 days a week1.375
Moderate exercise 3–5 days a week1.55
Hard exercise 6–7 days a week1.725
Very active or physical job1.9

To lose or gain weight, the calculator adds or subtracts about 7,700 kcal per kilogram (3,500 kcal per pound) spread over a week.

Worked example

A 30-year-old man, 175 cm, 75 kg, moderately active:

  • BMR = 10 × 75 + 6.25 × 175 − 5 × 30 + 5 = 1,699 kcal
  • Maintenance = 1,699 × 1.55 ≈ 2,633 kcal a day
  • To lose 0.5 kg a week: about 2,633 − 550 = 2,083 kcal a day

A 35-year-old woman, 165 cm, 62 kg, lightly active: BMR ≈ 1,315 kcal and maintenance ≈ 1,808 kcal a day.

Tips for using your calorie number

  • Start with maintenance and track your weight for a couple of weeks before cutting.
  • Aim for slow, steady change. Losing 0.25 to 0.5 kg a week is easier to sustain and helps keep muscle.
  • Prioritise protein when cutting calories — the macro calculator splits your calories into protein, carbs and fat.
  • Be honest about activity. Most people overestimate it; if in doubt, choose the lower level.
  • Recalculate as your weight changes, because a lighter body needs fewer calories.

Who should be careful

Calorie estimates are for healthy adults. They are not suitable for pregnancy or breastfeeding, for children and teenagers who are still growing, for people with eating disorders, or for medical conditions that affect metabolism or weight. Talk to a doctor or registered dietitian in those cases. To understand your weight first, see the BMI calculator; for your resting needs with three different formulas, try the BMR calculator. This is general information, not medical advice — see our disclaimer.

Frequently asked questions

How many calories should I eat a day?

It depends on your size, age, sex and how active you are. A 30-year-old man who is 175 cm tall, weighs 75 kg and exercises 3–5 days a week needs about 2,630 calories a day to keep his weight steady. A 35-year-old woman who is 165 cm and 62 kg with light exercise needs about 1,810.

How many calories should I eat to lose weight?

A deficit of about 500 calories a day below your maintenance level leads to roughly 0.5 kg (1 lb) of weight loss a week. Larger deficits work faster but are harder to keep up and can cost muscle. Most adults shouldn’t go below about 1,200 (women) or 1,500 (men) calories a day without medical supervision.

What is TDEE?

Total daily energy expenditure: the calories you burn in a day, including your resting metabolism (BMR), daily movement, exercise and digesting food. The calculator estimates it by multiplying your BMR by an activity factor.

Which formula does this calculator use?

The Mifflin-St Jeor equation from 1990. Studies comparing formulas with measured metabolism found it the most accurate for most healthy adults, and it is widely used by dietitians.

Why is my weight not changing on the calories shown?

Calculators give an average estimate; real needs can differ by 10% or more. Food tracking is also rarely exact. Track your weight for two to three weeks, then adjust by 100 to 200 calories a day.

What is the difference between kcal and kJ?

Food labels in the US and UK usually show kilocalories (kcal, often just called calories). Australia, New Zealand and the EU often show kilojoules too. 1 kcal = 4.184 kJ.

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