Calorie Calculator

Start from your own maintenance figure and subtract, rather than from a round number you heard somewhere. A 500-calorie daily deficit is the conventional step because it works out at roughly half a kilo a week, and that is the gap shown either side of maintenance here. A smaller deficit is entirely valid and usually easier to hold for the months that actually change anything. What is not valid is cutting as low as you can stand: under about 1,000 calories a day it becomes hard to get enough protein, iron and calcium from food at all, which is why no loss target below that figure is printed.

BMR is what your body spends staying alive with no activity at all — breathing, circulation, holding your temperature, running your brain and organs. For most adults it is the majority of the day's total. TDEE is that figure multiplied by how much you move, and it covers everything from deliberate training to walking to the kitchen. The distinction matters because people sometimes find their BMR, decide it looks like a sensible number to eat, and start eating hundreds of calories below what their day costs. Resting metabolism is an input to the calculation, not a target to eat to.

Treat the answer as a starting hypothesis, not a measurement. Mifflin-St Jeor predicts an average for healthy adults of a given age, sex, height and weight, and real people scatter around that average for reasons the inputs cannot capture — how much muscle you carry, thyroid function, medication, pregnancy, illness. The only way to find your own figure is to eat at the estimate for two or three weeks, weigh yourself consistently, and adjust from what the scale did rather than from what the equation said. The note under the results says as much, and it is the honest position: the arithmetic is exact, the biology it models is not.

Pick by your whole week, not by your training plan. The five options are a desk job with little exercise, exercise one to three days a week, three to five days, six to seven days, and a physical job or twice-daily training — multiplying your resting figure by 1.2, 1.375, 1.55, 1.725 and 1.9 respectively. The step from the first to the second is about 15 per cent of everything you eat, which is larger than most food-tracking errors. If you are torn between two levels, take the lower one: eating slightly under an overestimate is an easier problem to notice and correct.

Two things usually happen at once. A smaller body costs less to run, so the maintenance figure you worked out at the start is no longer the one that applies — worth re-entering your current weight every few kilos rather than every few months. And portions drift: measured amounts become estimated ones, the oil in the pan and the milk in the coffee stop being counted, and a few hundred calories reappear without anything feeling different. Weight also moves for reasons that have nothing to do with fat, so a fortnight of readings tells you far more about direction than any single morning does.

Nowhere off your machine. The equation is a few lines of arithmetic executed in the page you are looking at, so there is no upload step and nothing for a server to record. One consequence is worth planning around: the values you set are written into the address bar so that a link reproduces the result, and only the ones you changed from the defaults are written at all, so an untouched calculator leaves a clean URL. Your weight and age can therefore turn up in a screen share, in browser history, or in a chat app's link preview. Trim the query string off before pasting the address somewhere public.

Generally not, when the daily total came from an activity multiplier — the exercise has been counted once already, and adding a watch's estimate on top counts it twice. Wearable and machine readings for cardio tend to run high, sometimes considerably, and they usually report gross rather than net expenditure, so part of the figure is resting energy you would have spent sitting down anyway. If your training genuinely swings week to week, the cleaner approach is one steady daily number that reflects a typical week, letting the busy and quiet days average out.

Because the equation carries a fixed sex term: at the same height, weight and age, the male figure comes out 166 calories higher before any activity multiplier is applied, which widens to roughly 250 on the daily total at a moderate activity level. That term stands in for average differences in body composition — more muscle and less fat at a given weight burns more at rest — rather than for anything about sex itself. Being a population average, it fits a lean woman poorly and a sedentary man poorly, which is the same limitation that applies everywhere else in a predictive equation.