TDEE & Calorie Calculator

Basal metabolic rate is what your body spends staying alive at complete rest: circulation, breathing, brain activity, and tissue maintenance. For most people it is 60 to 70 percent of everything they burn. Total daily energy expenditure is that figure plus everything else, which means deliberate exercise, incidental movement such as walking and fidgeting, and the energy cost of digesting food. This calculator estimates BMR from an equation, then multiplies it by an activity factor to reach TDEE. The multiplication is a shortcut: it bundles three genuinely different things into one number, which is exactly why the activity level is the weakest link in the chain.

Use Mifflin-St Jeor if you do not know your body composition. It was published in 1990 on a more recent cohort than Harris-Benedict and has held up better against measured resting energy in modern populations, which is why it is the usual default. Use Katch-McArdle if you have a body-fat percentage from a DEXA scan, a set of calipers, or a reliable measurement. It works from lean mass alone and uses no sex, height, or age term, so it reads a lean or very muscular person far better than an equation that only knows your height. The revised Harris-Benedict is included because it is still widely quoted and worth seeing: for most bodies it returns the highest of the three, and that gap is a useful reminder of how much slack there is in any prediction.

Individually, less accurate than the tidy number suggests. Prediction equations for resting metabolic rate typically land within about 10 percent of a measured value for most people, but a meaningful minority sit further out, and the activity multiplier adds error on top of that. Two people matched on height, weight, age, and sex can genuinely differ by several hundred kilocalories a day through body composition, thyroid function, and how much they move without noticing. The practical answer is to treat the estimate as a hypothesis: eat at it consistently for two or three weeks, track weight as a weekly average rather than a daily reading, and adjust from what actually happened.

Lower than you think, most likely. Sedentary at 1.2 describes a seated job with no structured training, and that covers a lot of people who feel busy. Lightly active at 1.375 is roughly one to three hours of exercise a week. Moderately active at 1.55 means three to five hours of real training, or shift work that keeps you walking, and it is the honest ceiling for most recreational trainers. Very active at 1.725 assumes six or more demanding sessions a week or physical work. Extra active at 1.9 is twice-daily training or heavy labour on top of a programme, and very few people genuinely belong there. Overstating activity is the single most common reason a calorie target does not work, because the multiplier is applied to your whole basal rate: one step up can add several hundred kilocalories a day.

Because it treats a moving target as a fixed one. The rule comes from the approximate energy density of stored body tissue, about 7,700 kilocalories per kilogram or 3,500 per pound, and it works reasonably well for the first few weeks. After that the arithmetic drifts, for two reasons. A smaller body costs less to move and to maintain, so both the basal rate and the activity cost fall as weight comes off, which shrinks the deficit even though the intake has not changed. Meanwhile, real intake tends to creep upward as a diet gets longer. A linear projection of a 500 kilocalorie daily deficit predicts roughly half a kilogram a week indefinitely; in practice loss flattens noticeably within a few months. Use the weekly figure to compare goals with each other, not as a forecast of where you will be in a year.

For people who train, the evidence supports roughly 1.6 to 2.2 grams per kilogram of body weight a day, with the upper end most valuable during a calorie deficit, where protein is what protects muscle while fat is being lost. That target is expressed per unit of body weight rather than as a share of calories for a simple reason: a percentage scales with intake instead of with body size. Twenty-five percent of a 1,500 kilocalorie deficit gives about 94 grams, which is fine for a small person and clearly short for a 100 kilogram one. Setting grams per kilogram first, then letting fat and carbohydrate divide the remainder, keeps the number attached to the body rather than to the diet.

It is the figure often quoted as the lower bound for women eating without medical supervision, with about 1,500 used for men, and this calculator flags any target that falls below them. Those are not safety guarantees so much as practical floors: below them it becomes genuinely difficult to hit protein and micronutrient needs from food, energy for training disappears, and the plan gets much harder to stick to. If the numbers here push a goal under that line, the better move is a smaller deficit held for longer, or more activity rather than less food. Very low calorie intakes have a legitimate clinical use, but they belong under the supervision of a doctor or a registered dietitian.

No, and a guess is worse than leaving it blank. It is optional, and without it the calculator runs Mifflin-St Jeor and Harris-Benedict as normal. What it unlocks is lean body mass, which is your weight minus fat mass, and with it the Katch-McArdle equation. That matters most at the extremes: a very muscular person and a much softer person of identical height, weight, age, and sex get the same answer from the other two equations but genuinely different resting rates, and lean mass is what separates them. If your figure comes from a DEXA scan or careful caliper measurements, enter it. If it comes from a bathroom scale's impedance reading, treat the result with corresponding caution.

Because two of the three published equations require it. Mifflin-St Jeor was fitted on male and female cohorts and carries a constant that differs by 166 kilocalories between them; the revised Harris-Benedict has separate coefficients throughout. That is a property of the source papers, which described population averages, not a claim about any individual. The averages exist mostly because of differences in typical body composition, which is why Katch-McArdle needs no sex term at all: once lean mass is known directly, the proxy is redundant. If the sex field does not describe you well, a measured body-fat percentage and Katch-McArdle will give you a better answer than either of the other two.

No. Height, weight, age, and body fat are health data, so none of it is uploaded, logged, or retained. Every equation on this page runs in your browser in plain JavaScript, there is no account and no cookie holding your measurements, and closing the tab discards everything you entered. The copy button puts a summary on your clipboard and nowhere else.