Calorie Calculator

Find how many calories you need per day to maintain, lose, or gain weight, based on your age, sex, size, and activity with the Mifflin-St Jeor equation.

Sex
Height cm
ft in
Activity level
  • Sedentary — little or no exercise
  • Light — exercise 1–3 days/week
  • Moderate — exercise 3–5 days/week
  • Active — exercise 6–7 days/week
  • Very active — hard exercise or physical job
BMR formula
  • Mifflin-St Jeor (recommended)
  • Harris-Benedict
  • Katch-McArdle (uses body fat)
Calories to maintain —kcal/day
Maintain weight—
Mild loss — 0.25 kg/week—
Weight loss — 0.5 kg/week—
Extreme loss — 1 kg/week—
Mild gain — 0.25 kg/week—
Weight gain — 0.5 kg/week—

Zigzag cycle — alternating days, same weekly total as maintenance:

Mon —
Tue —
Wed —
Thu —
Fri —
Sat —
Sun —

Estimated with the Mifflin-St Jeor equation.

Your daily calorie needs are the amount of energy your body uses in a day. Eat around that number and your weight stays stable; eat consistently more or less and you gain or lose. This calculator estimates that target from your age, sex, height, weight, and activity level.

How it works

We first estimate your Basal Metabolic Rate (BMR) — the calories you burn at complete rest — using the Mifflin-St Jeor equation, the most accurate formula for the general population. We then multiply BMR by an activity factor to get your Total Daily Energy Expenditure (TDEE), the calories you burn on a typical day.

From there, weight-change targets are simple arithmetic: roughly 7,700 kcal ≈ 1 kg of body fat, so a 500 kcal/day deficit produces about 0.5 kg (1 lb) of loss per week, and a similar surplus supports gradual gain.

Choosing a target

  • Maintain: eat at your TDEE.
  • Lose weight: a 250–500 kcal/day deficit is sustainable for most people.
  • Gain weight/muscle: a 250–500 kcal/day surplus, paired with resistance training, favours lean gains over fat.

Avoid extreme deficits. Eating too little slows progress, costs muscle, and is hard to stick to. Track your actual weight over 2–4 weeks and adjust by ±100–200 kcal if the trend isn’t matching your goal.

Zigzag (calorie cycling)

The calculator also shows a zigzag schedule — seven days that alternate higher and lower intakes but add up to the same weekly total as eating at maintenance every day. Some people find cycling calories this way easier to sustain (bigger meals on training or social days), and it can help avoid the plateau feeling of a flat daily number. The weekly average is what matters, so any pattern that hits the same total works.

You can also switch the results between kcal and kilojoules (kJ) — 1 kcal = 4.184 kJ — which is handy if your country’s food labels use kilojoules.

Limitations

Calorie formulas are estimates, not measurements. Body composition, hormones, medications, sleep, and non-exercise movement all shift real needs. Treat the result as a well-informed starting point, and let the scale (and how you feel) fine-tune it.

Frequently asked questions

How many calories should I eat a day?

It depends on your age, sex, height, weight, and activity level. This calculator estimates your maintenance calories, then shows targets for gradual weight loss or gain. A common, sustainable rate is a 500 kcal/day deficit for about 0.5 kg (1 lb) of loss per week.

How many calories to lose weight?

Eat fewer calories than you burn. Roughly 7,700 kcal equals 1 kg of body fat, so a deficit of about 500 kcal/day gives around 0.5 kg of loss per week. Very aggressive deficits are hard to sustain and can cost muscle, so most guidelines advise a moderate pace.

Are these calorie numbers exact?

No — they are well-validated estimates. Real needs vary with genetics, body composition, medications, and daily movement. Use the number as a starting point and adjust based on how your weight actually changes over 2–4 weeks.

References