Calorie Calculator

Your daily requirement is mostly set by how much tissue you carry and how much you move it. Age, sex, height, weight and activity explain most of the gap between two people — the rest comes from genetics, hormones, sleep, illness and how much you fidget, none of which a calculator can see.

For rough bearings: adult men usually sit somewhere between 2,000 and 3,000 kcal a day to hold their weight, and adult women between 1,600 and 2,400. A tall, active 25-year-old and a short, sedentary 70-year-old can be a thousand calories apart without either being unusual.

There is also a floor. Eat far too little and your body starts covering the essentials by taking apart the things you would rather keep, muscle included. Common clinical guidance puts the unsupervised minimum around 1,200 kcal a day for women and 1,500 for men.

1. Get a baseline. Use the calculator above. If you know your body fat percentage, switch the equation to Katch–McArdle — it works from lean mass and tends to be the most accurate of the three.
2. Pick a rate, not a number. A kilo of body fat is roughly 7,700 kcal, so a 550 kcal daily gap works out near half a kilo a week. Going past about a kilo a week is where the trade-offs start to bite; if you want to, do it with a doctor or dietitian watching.
3. Choose how you will track. Paper, a spreadsheet, or an app. Apps win on friction — most can read a barcode or a photo and fill in the numbers for you — but the method that you will still be using in six weeks beats the method that is theoretically best.
4. Re-check every few weeks. Your BMR falls as you get lighter, so a target that worked in week one will stall by week eight. Weigh yourself under the same conditions — same time of day, before breakfast — and judge on weekly averages, not single mornings.
5. Keep going. Consistency does more here than precision.

Calorie counting is not an exact science, and it says nothing about the quality of what you eat. Calories in minus calories out is a real constraint, but foods differ in how full they leave you, how much energy digesting them costs, and what nutrients come along for the ride.

Most people underestimate what they eat, often by a wide margin. Logging for even a fortnight tends to rearrange your sense of proportion: a handful of crisps stops being free, and you discover which of your regular meals is doing the damage.

It also turns a vague intention into something you can act on. "Eat less" gives you nothing to check against; "1,850 today" does. And once you can see that a 220-calorie packet of sweets is about forty minutes of brisk walking, the trade becomes concrete rather than moral.

Portion habits shift on their own after a while. People fill the plate they are given and finish it, and restaurant portions have quietly taught most of us that three servings is one meal.

Stay on a reduced intake long enough and your body adapts — the deficit shrinks even though the number on your plan has not moved. Zigzagging means holding the weekly total steady while varying the days: a couple of higher days, several lower ones.

Say your target is 14,000 kcal a week. You could eat 2,000 every day, or 2,300 on three days and 1,775 on the other four. Same total, less predictability — and a week that has room in it for a dinner out without the plan collapsing.

There is no settled research on the best pattern. A 200–300 kcal spread between high and low days is a sensible default; people with higher activity levels can go wider. The two schedules the calculator generates above are both built from your own numbers.

• Mifflin–St Jeor — the default here and the one most dietitians reach for. Published in 1990, and generally the most accurate of the weight-based equations for the general population.
• Revised Harris–Benedict — the 1919 original, updated in 1984. Still widely used, usually reads a little higher than Mifflin.
• Katch–McArdle — works from lean body mass instead of total weight, so it needs a body fat percentage. If you have a reliable one, this is the most accurate of the three, particularly for lean or heavily muscled people.

Whichever you pick, the output is an estimate with a real error bar around it. Two weeks of weighing yourself will tell you more about your true maintenance level than any formula.

• Decide where the calories are being tracked before you need them — the first skipped log is usually the one you had no plan for.
• Weigh in on a schedule and look at the weekly average. Day-to-day swings are mostly water and timing.
• Recalculate every 4–6 kg of change, or every couple of months, whichever comes first.
• Watch more than the scale. Losing weight while losing muscle is not the same result as losing weight while keeping it.

1 cup ≈ 240 ml · 1 tablespoon ≈ 14 g. Browse the full food list →

Illustrative days, not prescriptions. Swap anything for something you would actually eat at the same calorie cost.

Averages. Fitness, terrain and how hard you actually go move these a long way in either direction — and a watch will usually read higher than this.

This is the whole reason a salad with dressing can out-calorie a sandwich: fat carries more than twice what protein or carbohydrate does, gram for gram.