TDEE Calculator

Total daily energy expenditure is everything your body burns in a day. It is the number a calorie target is set against, and it has four components.

Basal metabolic rate, 60–70% — staying alive at rest.

Thermic effect of food, about 10% — digesting and absorbing what you eat. Protein costs the most to process, at 20–30% of its own calories.

Exercise activity, 5–15% — deliberate training.

Non-exercise activity thermogenesis, 10–30% — walking, standing, fidgeting, gesturing, everything not classified as exercise.

The last one is where almost all the variation between people lives.

The multipliers, and what they actually mean

Written out, both steps:

BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 for men, − 161 instead of + 5 for women — Mifflin-St Jeor.

TDEE = BMR × activity factor, the factor being one of the five below.

For the 30-year-old man above, whose BMR is 1,533:

The spread from sedentary to athlete is over a thousand calories. Choosing one level too high builds a 250-calorie error into every target you set afterwards, which is enough to erase a modest deficit entirely.

Almost everyone picks too high. The categories are worded generously and people count intention rather than behaviour. An office worker who trains three times a week and otherwise sits is light, not moderate — the three hours of training are a small part of 168 hours. Choose one level below your instinct and adjust upward only if the weight does not move.

NEAT is the hidden variable

Non-exercise activity thermogenesis is everything you do that is not training or sleeping, and it varies enormously between people and within the same person from day to day.

Overfeeding studies have found differences of nearly 2,000 calories a day in how much people unconsciously increase movement when given surplus food. Some fidget, stand and pace more; others do not. Nobody in either group decided to.

It also falls when you diet. Reduced spontaneous movement is part of how the body defends its weight, and it is invisible — you do not notice yourself taking the lift, sitting sooner, gesturing less. This is a large part of why weight loss slows beyond what the arithmetic predicts.

The practical response is to make NEAT deliberate. A daily step target — 8,000 to 10,000 — turns an unconscious variable into a controlled one, and walking is the only meaningful activity that adds no recovery cost to training.

Setting a target

To lose fat, subtract 15% to 20% from TDEE. For the sedentary case above, 1,839 becomes roughly 1,500. A deficit of 500 calories a day is about half a kilogram of fat a week, which is the standard recommendation because it is fast enough to see and slow enough to preserve muscle.

To maintain, eat at TDEE. Worth doing deliberately for a few weeks after a diet, since going straight from a deficit back to unstructured eating is where regain happens.

To build muscle, add 10% to 15%. More than that adds fat rather than accelerating muscle, which has an upper rate of gain that food cannot override.

The 3,500 calories per pound rule — 7,700 per kilogram — is the standard shorthand and it overstates results over long periods, because TDEE falls as you get lighter. Expect early weeks to match the arithmetic and later ones to lag.

Recalculate as you go

TDEE is not a constant. It falls as weight falls, because a smaller body costs less to run and because activity becomes cheaper.

Someone dieting from 90 kg to 80 kg loses roughly 100 to 150 calories a day of expenditure from the weight change alone, before adaptive effects. A target set at 90 kg becomes a much smaller deficit at 80 kg, and eventually no deficit at all. This is the mechanism behind almost every plateau.

Recalculate every 5 kg, or whenever progress has stalled for three consecutive weeks with the target being followed accurately. The alternative — cutting calories further each time progress slows — leads somewhere unsustainable.

Tracking honestly

The formula's estimate is a hypothesis. Your own data tests it.

Weigh yourself at the same time daily, ideally on waking after using the bathroom, and use the seven-day average rather than any single reading. Daily fluctuations of one to two kilograms from water, sodium, carbohydrate intake and digestive contents are normal and mean nothing; the weekly trend means everything.

If the average has not moved in three weeks and the target has genuinely been hit, the TDEE estimate was too high. Reduce it by 10% and try again.

The other half of honest tracking is the intake side. Fitness trackers overestimate exercise calories by 30% to 90% in validation studies, and eating back those calories is the most reliable way to convert a real deficit into no deficit. Treat any calories a device credits you with as approximately zero.

Exercise burns less than the machine says

The calorie figure on a treadmill or a smartwatch is one of the most consistently overstated numbers in fitness.

Cardio equipment typically ignores that you would have burned energy anyway during that half hour. The honest figure is the additional expenditure, which is the displayed number minus roughly your resting rate for the same period — around 60 to 80 calories an hour for most adults.

Wearables fare worse. Validation studies find errors of 30% to 90% for energy expenditure, even from devices whose heart rate tracking is accurate, because converting heart rate to calories requires assumptions about fitness and efficiency that the device cannot know.

The number that does hold up is step count, which is measured rather than inferred. Roughly 0.04 calories per step per kilogram of body weight is a serviceable estimate — about 300 calories per 10,000 steps at 75 kg.

This is why the activity multiplier exists at all: it folds average activity into the estimate so that individual sessions do not need to be counted. Adding tracked exercise calories on top of a multiplier that already includes them is double-counting, and it is the reason many people eating "at their deficit" are not in one.

Choosing between the multiplier and tracking

Two workable approaches, and they should not be mixed.

Multiplier method. Pick an activity level, eat at the resulting number every day regardless of what you did, and adjust after three weeks based on the trend. Simple, and the errors average out across the week.

Sedentary plus tracked exercise. Use the 1.2 multiplier as a base and add a conservative estimate for each session — half of what the device claims. More responsive to a schedule that varies a lot, and more work.

For most people the first is better, because consistency matters more than precision and a fixed daily target is far easier to hold.

What this calculator assumes

• BMR from Mifflin-St Jeor unless you supply body fat, in which case Katch-McArdle is used.
• Standard activity multipliers from 1.2 to 1.9, applied to BMR.
• The thermic effect of food is inside the multiplier rather than added separately.
• The result is an estimate with roughly ±200 calories of individual variation. Adjust from your own results after two to three weeks.
• Deficits and surpluses are calculated as a percentage of TDEE, not of BMR.