Calorie Calculator

Food Energy Converter

Convert between Calories and the other common food energy units.

The three BMR equations

Every estimate on this page starts with a basal metabolic rate — the energy you would burn in a day completely at rest. The Harris-Benedict equation was among the first attempts to compute it, and its 1984 revision stayed standard until 1990, when the Mifflin-St Jeor equation proved more accurate in study after study. Katch-McArdle takes a different route: it calculates from lean body mass, so it can beat both for lean people who know their body fat percentage. In the Settings you can switch between them and watch the targets move.

W is weight in kg, H is height in cm, A is age, and F is body fat as a fraction. The BMR is then multiplied by an activity factor (from 1.2 for sedentary to 1.9 for a physical job with daily intense training) to get the calories that maintain your current weight. Losing a pound a week means eating about 500 a day below that line; gaining, the mirror image. Two cautions: cutting more than 1,000 a day courts muscle loss, and as muscle goes, so does BMR — which is why very aggressive diets so often rebound. And keep minimums in view: roughly 1,500 calories a day for men and 1,200 for women unless a doctor is supervising.

Calorie counting, step by step

1. Get your BMR from one of the equations above — Katch-McArdle if you know your body fat percentage. Treat the number as a good approximation, not gospel: eating exactly 500 below it will not always produce exactly a pound a week.
2. Set the goal. A pound is about 3,500 calories, so each 500 calories a day of deficit is roughly a pound a week. More than 2 lb (1 kg) a week is a red-flag pace — if that is the plan, involve a doctor or a registered dietitian.
3. Track honestly. An app, a spreadsheet, or a paper journal all work. Weigh or measure a few typical meals once, and estimating the rest gets much easier.
4. Judge by the week, not the day. Water retention and meal timing swing daily weight wildly. Weigh under the same conditions (morning, before breakfast) and compare weekly averages.
5. Adjust and keep going. As you lose weight your BMR drops with it, so re-run this calculator every few kilograms and reset the target.

Counting works because, at the level of energy balance, a calorie is a calorie: sustained deficit loses weight, sustained surplus gains it — the famous "Twinkie diet" experiment proved the arithmetic even on cake snacks, while also proving nothing about health. Food quality still matters for hunger, nutrients, and how many of the label's calories your body actually absorbs, which is why minimally processed food makes any target easier to live on.

Zigzag calorie cycling

Bodies adapt. Weeks into a flat restriction, the body settles into the lower energy budget and progress can plateau. Zigzag cycling fights that by alternating high- and low-calorie days inside the same weekly total — eat at maintenance twice a week and below target five days (schedule 1), or ramp up and down gradually across the week (schedule 2). The side benefit is freedom: the high days can be placed on the days with the family dinner or the work lunch, as long as the week adds up. There is no proven "best" pattern; swings of a few hundred calories around the target are typical, and the schedules in your result keep every day at or above the recommended minimum.

How many calories do you actually need?

It depends on age, weight, height, sex, activity, and general health — a tall, active 25-year-old man can need twice what a small, sedentary 70-year-old woman needs. As rough guides, adult men typically maintain on 2,000–3,000 calories a day and adult women on 1,600–2,400. Surviving takes far less than thriving: running the body on bare survival rations means it funds only the essentials and skips the rest, so treat the minimums above as floors, not targets.

Not all calories behave the same

Calories come mainly from carbohydrates, protein, and fat (plus alcohol, which at ~7 kcal per gram of pure "empty" energy is best treated as a luxury). Foods differ in how filling they are, how much energy digestion itself burns, and how honest their labels are — 500 calories of carrots and 500 of popcorn do not leave you equally hungry. Drinks deserve special suspicion: they supply roughly a fifth of a typical diet's calories and barely dent hunger. Water, tea, and unsweetened coffee are the freebies.

Calories in common foods

* 1 cup = ~250 milliliters, 1 tablespoon = 14.2 grams.

Calories burned by common exercises

Energy from common food components

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