How many calories do you need a day?

How this calculator works

First it estimates your resting metabolism (BMR), the energy your body uses just to stay alive, with the Mifflin-St Jeor equation. In studies comparing prediction formulas it is the most accurate for most adults.

Then it multiplies your BMR by an activity factor to get your maintenance calories (TDEE): the calories that keep your weight stable. Finally it adds or removes calories based on your goal.

The formula

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

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

Maintenance = BMR × activity factor, from 1.2 for a sedentary day to 1.9 for hard physical work.

How big should the deficit be?

A deficit of about 500 kcal a day usually leads to losing around 0.5 kg (1 lb) a week at first. Weight loss slows over time because a lighter body burns less energy, so progress after a few months is normal to be slower.

A smaller deficit of 250 kcal is easier to keep. Very aggressive deficits make you hungrier, cost muscle and are hard to sustain.

Why protein matters

When you eat less, enough protein helps you keep your muscle and feel full. For most active adults trying to lose weight, 1.6 g per kg of body weight a day is a good target. That's what the calculator shows.

Why your real number can be different

Formulas describe averages. Two people with the same age, height and weight can burn a few hundred calories a day more or less. Use the result as a starting point, track your intake for a few weeks and adjust based on what your weight actually does.

Frequently asked questions

How many calories should I eat to lose weight?

Start from your maintenance calories and remove about 500 kcal a day to lose around 0.5 kg a week, or 250 kcal for a gentler pace. Most women should not go below 1,200 kcal and most men below 1,500 kcal a day without medical supervision.

What is the difference between BMR and TDEE?

BMR is the energy you burn at complete rest. TDEE, or maintenance calories, adds everything you do during the day: walking, working, training and digesting food.

Is the Mifflin-St Jeor equation accurate?

It is considered the most reliable formula for healthy adults and predicts resting metabolism within 10% for most people. It is less accurate for very muscular people, athletes and people with obesity.

Should I eat back the calories I burn with exercise?

The activity level already includes your usual exercise, so you don't need to add workouts on top. If you do something unusually long, like a hike or a long ride, eating part of those calories back is reasonable.