How this calculator works
First, it estimates how many calories your body burns at rest using the Mifflin-St Jeor equation, which a major review found to be the most accurate formula for most adults. Then it multiplies that by your activity level to get the calories you burn in a normal day, and adjusts it for your goal: 500 calories less to lose fat, or 300 calories more to build muscle.
The calculator sets protein at 0.8 grams per pound of body weight (1.8 grams per kilogram), a common target for people who lift. Fat gets 25% of your calories, and carbs fill in the rest. For the full method with a worked example, see How to calculate your macros.
Switch to BMR at the top to see the calories your body burns at rest to keep your heart, lungs and organs working.
Switch to TDEE at the top to see your calories on their own. Your TDEE, or total daily energy expenditure, is how many calories you burn in a normal day. Eating 500 calories a day less than that works out to about a pound (0.45 kg) a week at first, and 250 less to about half a pound. Progress slows as you get lighter, so it helps to recalculate every 10 to 15 lb (4.5 to 7 kg). To see how long it will take to reach your goal weight, try our free Weight Loss Calculator.
Common questions
What's the difference between BMR and TDEE?
Your BMR is what your body burns at rest to keep you alive. Your TDEE adds everything else: moving around, working out and digesting food, so it's the number your calorie target starts from. For more, see TDEE vs BMR: what's the difference?
How big a calorie deficit is safe?
For most people, 250 to 500 calories a day below their TDEE is a good range. It's enough to see steady progress without feeling drained, and it makes it easier to hold on to muscle.
How accurate is this?
It's an estimate. Even the best formula can be off by around 10% for any one person, so treat your numbers as a starting point. Track for two to three weeks, compare your weekly average weight, and adjust by 100 to 200 calories if things aren't moving the way you want.
Why is protein based on body weight?
Your protein needs depend on how much you weigh. Basing protein on your weight keeps it high when you cut calories, and that's when protein does the most to protect your muscle. For more, see How much protein do I need a day?
Does this work for women?
Yes. The formula makes a small adjustment for women when it estimates the calories you burn at rest, so it asks for your sex. Everything else, including protein, works the same way for men and women.
What are good macros for weight loss?
Start with your calories, about 500 a day below your TDEE. Then keep protein high, around 0.8 grams per pound of body weight (1.8 grams per kilogram), so you hold on to your muscle while you lose fat. Fat at about 25% of your calories, with carbs for the rest, works well for most people. Pick Lose fat and this calculator gives you those numbers.
Which activity level do I pick?
Most people with a desk job who work out three to five days a week are "moderately active." If you're stuck between two levels, pick the lower one. If you lose weight faster than you expected, you can add calories later.
