Calorie deficit calculator

Tell us about yourself and your goal. We'll estimate how much to eat each day, and how long it may take.

Common questions

What is a calorie deficit?

You are in a calorie deficit when you eat fewer calories than your body uses in a day. Your body makes up the difference from stored energy, which leads to weight loss over time.

How is my number calculated?

We estimate the calories you burn at rest with the Mifflin-St Jeor equation: 10 × weight in kg + 6.25 × height in cm − 5 × age, then + 5 for men or − 161 for women. If you enter your body fat, we use the Katch-McArdle equation instead: 370 + 21.6 × lean mass in kg. Multiplying by your activity level, from 1.2 to 1.9, gives the calories that hold your weight. Losing 1 lb a week takes off 500 calories a day, and 2 lbs takes off 1,000.

How big should my calorie deficit be?

A deficit of about 500 to 1,000 calories a day is a common starting point, and works out to roughly 1 to 2 lbs a week. Bigger is not always better: very large deficits are harder to keep up and can cost you muscle along with fat.

Is there a minimum number of calories I should eat?

Eating fewer than about 1,200 calories a day for women or 1,500 for men is generally not advised without medical supervision, because it is hard to get enough nutrients. If your target falls below that, we let you know. A slower pace or more activity can keep you above it.

Why might my results differ from this estimate?

These equations estimate an average, and your real burn can be higher or lower. The timeline also uses the rule of thumb that 3,500 calories equals about 1 lb, and your body burns less as you get lighter, so progress usually slows over time. Treat this as a starting point: check your progress after a few weeks and adjust.