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Calorie Calculator

Estimate how many calories you burn each day and how many to eat to keep, lose or gain weight, using the Mifflin-St Jeor formula.

Rules last checked 12 November 2026Every step shown3 sources

Your numbers are saved in this browser.
years

For adults. Children and teenagers need a doctor or dietitian to set their calories.

cm
kg

To keep your weight

2,220 calories a day

To lose about 0.5 kg a week
1,720 a day
To gain about 0.5 kg a week
2,720 a day
At complete rest (BMR)
1,620 a day

You burn about 2,220 calories a day. Eating around 1,720 a day would lose roughly half a kilo a week.

How it's worked out

  1. Resting energy (Mifflin-St Jeor)10 × 70 + 6.25 × 170 − 5 × 30 + 51,618 kcal
  2. Times your activity level1,618 × 1.3752,224 kcal
  3. Weight changeabout 500 kcal a day below or above, for roughly 0.5 kg a week at first; loss usually slows over the months as your weight falls1,720 / 2,720 kcal
  • An estimate: real needs vary by about 10% either way. Watch your weight for 2 to 3 weeks and adjust.
  • Targets never go below 1,500 calories a day without medical advice.

The formula

Resting energy = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 (men) or − 161 (women)

Worked example

A 30-year-old man of 70 kg and 170 cm burns about 700 + 1,062.5 − 150 + 5 = 1,617.5 calories at rest. Moderately active (× 1.55), that's about 2,510 a day to keep his weight.

Questions people ask

How many calories do I need a day?

It depends on your size, age, sex and activity. The calculator estimates your resting energy with the Mifflin-St Jeor formula and multiplies it by your activity level.

How many calories should I cut to lose weight?

About 500 a day below your maintenance level loses roughly 0.5 kg a week at first for most people. Loss usually slows over the months as your weight falls. Bigger cuts are harder to keep up and can cost muscle.

What is the lowest safe intake?

Harvard Health advises not going below 1,200 calories a day for women or 1,500 for men without a health professional's supervision. These match the lower ends of the US adult obesity guideline (AHA/ACC/TOS, 2013), so the calculator never suggests less.

Why Mifflin-St Jeor?

Studies comparing the common formulas found it the most accurate for most adults, which is why dietitians widely use it.

Formula and rules last checked 12 November 2026Written and tested by the CalculatorDex teamReport a problem

Sources: Mifflin et al. (1990), American Journal of Clinical Nutrition · Harvard Health Publishing, Calorie counting made easy · Jensen et al., 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults