Calorie Calculator
How many calories a day to keep, lose or gain weight, worked out with the NASEM 2023 equations from your age, height, weight and activity.
How maintenance and deficit calories are worked out
The app runs the same four steps.
1. Maintenance
Sex, age, height, weight and activity go into the NASEM 2023 equations. Out comes what you burn in a normal day, rounded to the nearest 10.
2. The deficit
A pace of 0.25, 0.5 or 0.75 kg a week takes 275, 550 or 825 calories a day off maintenance. A pace over 1% of your weight a week isn't offered.
3. The minimum
No goal drops under 1,200 for the female formula, or 1,500 for the male one and "prefer not to say". If even 0.25 kg a week would cross it, the goal is the minimum itself.
4. Your weight trend
Any estimate can be 250 calories or more out in either direction. Log your meals and weigh in for three or four weeks. Only the trend shows your real maintenance.
How much activity changes the answer
Same woman, 35, 165 cm and 68 kg: 540 calories a day between mostly sitting and very active. Pick the level of a normal week, not your best one.
Questions about daily calories
How many calories should I eat a day?
For a 35-year-old woman at 165 cm and 68 kg, about 2,240 a day keeps her weight steady when she's lightly active. Mostly sitting it's 2,080, very active 2,620. Your number depends on sex, age, height, weight and activity, so put yours in above instead of using a round figure.
How many calories should I eat to lose weight?
Take about 550 off your maintenance number for 0.5 kg (1 lb) a week. The woman above goes from 2,240 to 1,690, or to 1,970 for the gentler 0.25 kg. At 68 kg the calculator doesn't offer 0.75 kg, because that's over 1% of her weight a week. No goal goes under 1,200 calories (female formula) or 1,500 (male formula and "prefer not to say").
What is a calorie deficit?
Eating fewer calories than you use in a day. Subtract your goal from your maintenance number: 2,240 minus 1,690 is a deficit of 550. A deficit of 275, 550 or 825 calories a day matches a loss of 0.25, 0.5 or 0.75 kg a week, and the calculator caps the pace at 1% of your body weight a week.
How many calories do I burn a day?
The same number as your maintenance calories: what you use in a normal day, activity included. A 40-year-old man at 180 cm and 90 kg, lightly active, burns about 2,990. The woman above burns 2,240. To lose weight you don't have to burn a set amount, because the deficit is how far your food sits under this number.
What is TDEE, and how do I calculate my maintenance calories?
TDEE (total daily energy expenditure) is your maintenance calories: eat that much and your weight stays steady. Enter your details above to calculate it. The NASEM 2023 equations behind it come from doubly labeled water studies, which measure the energy people actually used. Calculators built on the 1990 Mifflin-St Jeor equation with an activity multiplier give different numbers, so check any of them against your weight trend over three or four weeks.
How do I eat in a calorie deficit?
Take the goal from the calculator, log what you eat against it and weigh in regularly. Read the weight trend over three or four weeks instead of one morning's reading, because any estimate can be 250 calories or more out either way. Keep protein at 1.2 to 1.6 g per kg a day while you eat less. The macro calculator turns your goal into grams.
How many calories should I eat a day by age?
Your maintenance number falls about 7 calories a year for women and 11 for men. The same woman (165 cm, 68 kg, lightly active) needs 2,320 at 25, 2,170 at 45 and 2,030 at 65. Age alone won't give you a number: at 35, going from mostly sitting to very active adds 540, more than the 290 that 40 years of aging take off.
Can you build muscle in a calorie deficit?
The calculator sets calories and can't predict muscle. If you try it, take the slowest pace, 0.25 kg a week (1,970 calories for the woman above, against 1,690 at 0.5 kg). Keep protein within 1.2 to 1.6 g per kg a day, the range in US dietary guidance for 2025–2030. The macro calculator uses the top of it, 1.6, for lifting or building muscle.