Calorie Deficit Calculator — How Many Calories Should I Eat?

Your details

Age

Weight (kg)

Height (cm)

Sex (for the equation)

Your activity level

—

Your daily needs (to maintain weight) · kcal/day

—

Basal metabolic rate · kcal/day

Your daily target for losing weight

Mild−250 kcal

— kcal/day

Moderate · recommended−500 kcal

— kcal/day

Strong−750 kcal

— kcal/day

The weekly estimate is rough and applies to the first weeks: as you lose weight you burn less, so progress slows. Judge by your 3–4-week average, not a single weigh-in.

Track your target in Suu

Enter your target in Suu, log meals by voice or photo, and see what your GPS workout burned on the same day.

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How we calculate it

First we estimate your basal metabolic rate (the energy you burn at rest) with the Mifflin-St Jeor equation: 10 × weight + 6.25 × height − 5 × age + 5 for men, and the same sum − 161 for women.¹ In a systematic review it was the most reliable of the common equations, predicting within ±10% of measured values in most people — individual error is still possible.²

We then multiply it by an activity factor to get your daily needs (the calories that keep your weight stable). To lose weight we go 250–750 kcal below that.

Activity level	Factor
Sedentary — Desk job, no exercise	1.2
Light — 1–3 days a week	1.375
Moderate — 3–5 days a week	1.55
Active — 6–7 days a week	1.725
Very active — Physical job + training	1.9

How big a deficit is safe?

According to the CDC, people who lose about 1–2 pounds (0.5–1 kg) a week are more likely to keep the weight off; for most people that's roughly a 500 kcal daily deficit.⁴
Harvard Health advises that, without professional supervision, intake shouldn't fall below 1,200 kcal a day for women or 1,500 for men; the calculator never sets a target below that.⁵
Weight loss isn't linear: body weight responds slowly to a change in energy, and as you lose weight you burn less.³ Re-run the calculation with your new weight every few weeks.

Frequently asked questions

How do you calculate a calorie deficit?

First find your daily needs: multiply your basal metabolic rate (Mifflin-St Jeor equation) by your activity factor. To lose weight, eat 250–750 kcal below that. If your daily needs are 2,200 kcal, a 1,700 kcal target is a 500 kcal deficit.

How many calories should I eat to lose weight?

About 500 kcal less than your daily needs — for most people that's around 0.5 kg a week. Without professional supervision, don't go below 1,200 kcal for women or 1,500 for men.

How much weight will I lose with a calorie deficit?

Roughly, a 500 kcal daily deficit equals about 0.45 kg a week. That's an estimate for the first weeks: as you lose weight you burn less and progress slows, and part of the fast early drop is water.

Is BMR the same as daily calorie needs?

No. BMR is the energy you burn at complete rest; daily needs add everyday movement and exercise on top. Base your weight-loss target on daily needs, not BMR.

Is this calculator right for everyone?

It's a general estimate for healthy adults over 18. If you are pregnant or breastfeeding, have a long-term condition or a history of eating disorders, or take medication, set your target with a dietitian or doctor.

This tool provides general information and is not medical advice. Consult a healthcare professional for your individual needs.