Estimate how many calories you burn each day and what to eat to maintain, lose or gain weight at a steady pace.
This estimates the calories needed to maintain your current weight (TDEE). Individual needs vary, so use it as a starting point, not a medical prescription.
The calculator first estimates your Basal Metabolic Rate (BMR), the calories your body burns at complete rest to keep you alive. It uses the Mifflin-St Jeor equation, which dietitians widely prefer because it has proved more accurate than older formulas. For men, BMR = 10 x weight (kg) + 6.25 x height (cm) - 5 x age + 5. For women, it is the same but with -161 at the end instead of +5.
BMR does not include movement, so it is multiplied by an activity factor to get your Total Daily Energy Expenditure (TDEE), the calories you burn in a typical day. The factors are 1.2 for sedentary, 1.375 for light activity, 1.55 for moderate, 1.725 for active and 1.9 for very active. Eating about your TDEE keeps your weight steady over time. Eating less produces weight loss and eating more produces weight gain, and the calculator shows targets for both.
If you know your body fat percentage, enter it for a more precise BMR. The calculator then switches to the Katch-McArdle equation, which is based on lean body mass: BMR = 370 + 21.6 x lean mass (kg), where lean mass is your weight minus your fat. It is often more accurate for people who are very lean or very muscular, because muscle burns more energy at rest than fat does.
Take a 30-year-old man who is 5'9" (175.3 cm) and weighs 160 lb (72.6 kg), with a moderate activity level. His BMR is 10 x 72.57 + 6.25 x 175.26 - 5 x 30 + 5 = 1,676 calories. Multiplied by 1.55, his TDEE is 2,598 calories a day. To lose about half a pound a week he would eat around 2,348, for a pound a week 2,098, and for two pounds a week 1,598. To gain a pound a week he would eat about 3,098.
Now a 35-year-old woman who is 5'5" (165.1 cm) and weighs 140 lb (63.5 kg), with light activity. Her BMR is 1,331 calories and her TDEE is 1,830. A deficit of 500 leaves 1,330 calories, which is above the usual minimum for women. A two-pound-a-week target would leave 830 calories, well below the 1,200 that health guidelines generally treat as a floor, so the calculator marks it with an asterisk and a note. It is a good example of why the faster targets are not suitable for everyone.
Activity level is the biggest lever in the calculation and the easiest to get wrong. For the 30-year-old man above, the same BMR gives 2,011 calories at the sedentary level, 2,598 at moderate and 2,891 at active, a spread of 880 calories a day depending on the box you tick. Choose the level that matches your real average week, not your best week:
If you are between two levels, pick the lower one. Overestimating activity is the most common reason a calorie target feels wrong in practice.
A pound of body fat holds roughly 3,500 calories, so a daily change of 500 calories adds up to about a pound a week (500 x 7 = 3,500). A change of 250 a day gives about half a pound a week, and 1,000 a day about two pounds. The CDC describes 1 to 2 pounds a week as a safe pace for most people, and many dietitians prefer the slower end because it is easier to sustain and helps protect muscle.
Keep in mind that this is a starting estimate, not a promise. As you lose weight your body needs fewer calories. The 30-year-old man above would need about 2,457 calories to maintain at 140 lb, roughly 141 fewer than at 160 lb, so a deficit shrinks over time unless you adjust. Recalculate every time your weight changes by about 5 to 10 pounds, or every month or so.
Eating far below your needs is hard to sustain and can leave you short of protein, vitamins and minerals. A commonly cited floor without medical supervision is 1,200 calories a day for women and 1,500 for men. When one of the targets falls below that level for your sex, the calculator flags it. Pregnant or breastfeeding women, teenagers, older adults and people with medical conditions have different needs and should get advice from a doctor or registered dietitian.
Consider a 35-year-old man who is 5'10" and weighs 180 lb with 20% body fat and a moderate activity level. His lean mass is 144 lb, or 65.3 kg. The Katch-McArdle equation gives a BMR of 370 + 21.6 x 65.32 = 1,781 calories and a TDEE of 2,760. Mifflin-St Jeor, using only height, weight and age, gives 1,758 and 2,724, close but not the same. Body fat changes the answer more for unusual builds. At the same weight, 30% body fat gives a Katch-McArdle BMR of about 1,604, while 10% gives about 1,957. Body fat estimates from scales and calipers are themselves rough, so treat the entry as an approximation.
Use the BMI calculator to see where your weight falls for your height, and the age calculator if you want your exact age. To work out what a percentage change in weight or calories looks like, try the percentage calculator. Food spending is part of the picture too, and the budget calculator helps you plan it.
What is the difference between BMR and TDEE?
BMR is the energy your body uses just to stay alive at rest, for breathing, circulation and cell repair. TDEE adds everything else, including walking, exercise and even fidgeting. TDEE is the more useful number, because it is what decides whether you gain, lose or maintain weight.
How many calories should I eat to lose weight safely?
A deficit of 250 to 500 calories below your TDEE is a common starting point, which works out to about half a pound to one pound of loss per week. The CDC describes 1 to 2 pounds a week as a safe rate. Avoid going below about 1,200 calories for women or 1,500 for men without medical supervision.
Is this calculator accurate for everyone?
It is a solid estimate for most healthy adults, usually within about 10% for many people. The Mifflin-St Jeor equation was built on average body compositions, so it is less precise for people with unusually high muscle mass or very high body fat. Entering a body fat percentage gives the calculator a better basis for those cases.
Does this work during pregnancy or breastfeeding?
No. Calorie needs during pregnancy and breastfeeding follow different guidelines. Talk to a doctor or registered dietitian for advice specific to your situation.
Does it work for teenagers or older adults?
The Mifflin-St Jeor equation was developed for adults, so the results are a rough estimate for anyone under 18. Older adults often have less muscle mass, and their needs can differ from the formula, so use the numbers as a guide and adjust based on real-world results.
I have a lot of muscle. Will this underestimate my needs?
Possibly, if you leave body fat blank. Muscle burns more energy at rest than fat does. Enter an estimate of your body fat percentage to use the lean-mass-based formula, and adjust based on how your weight actually trends over a few weeks.
How often should I recalculate?
Whenever your weight changes by more than about 5 to 10 pounds, or every month or so while you are trying to lose or gain. TDEE shifts as your body weight changes, so a number that was right at the start of a diet will not stay right for the whole journey.
Why didn't my real-world results match the number here?
Every formula is an estimate, and actual metabolism varies more than these equations can capture, as does how accurately people track food. Eat at the suggested level for two to three weeks while tracking your weight, then adjust by 100 to 200 calories based on what actually happens.