Calories to maintain
—kcal / day
Enter your height, weight and age to see your result.
Daily target by goal
| Level | Calories a day |
|---|---|
| Fast weight lossLose about 1 kg a week | — |
| Steady weight lossLose about 0.5 kg a week | — |
| Gradual weight lossLose about 0.25 kg a week | — |
| Maintain weightHold steady at your current weight | — |
| Gradual weight gainGain about 0.25 kg a week | — |
| Steady weight gainGain about 0.5 kg a week | — |
These assume a fixed 7,700 kcal per kilogram of body fat (3,500 per pound), which real bodies only approximate — a shrinking body also needs less energy to run. Weigh yourself weekly for a month and adjust from your own trend. Targets are never shown below 1,200 kcal for women or 1,500 for men; if the arithmetic asks for less, the plan needs a dietitian rather than a smaller number.
What your calorie needs are
The number this calculator gives you is your total daily energy expenditure — how much your body spends in twenty-four hours, all in. Eat that much and your weight holds. Eat less and it falls; eat more and it rises. Everything else about calories is detail on top of that one relationship.
It is made of four parts, and they are wildly unequal in size. Your resting metabolism takes 60 to 70 per cent of it. Digesting food takes around 10 per cent. Deliberate exercise — the part everyone thinks about — usually takes 5 per cent or less. The remainder is non-exercise activity: walking to the bus, standing up, carrying things, fidgeting. For most people that last category is several times larger than their gym sessions, which is why a job change can move weight more than a training programme does.
How the calculator works
Two steps. First it estimates your basal metabolic rate with the Mifflin-St Jeor equation, then it multiplies that by a factor for how much you move.
Daily calories = BMR × activity multiplier
Mifflin-St Jeor is used here because it is the most reliable of the common equations. The BMR calculator lets you compare it against Harris-Benedict and Katch-McArdle.
If you want to see the resting figure on its own, or try the other equations, the BMR calculator shows all three side by side and lists what each activity multiplier is worth.
The goal rows underneath the result then add or subtract a daily amount based on how fast you want your weight to change, using the standard conversion of roughly 7,700 calories per kilogram of body fat.
| Goal | Weekly rate | Daily calories |
|---|---|---|
| Fast weight loss | Lose about 1 kg a week | −1,100 |
| Steady weight loss | Lose about 0.5 kg a week | −550 |
| Gradual weight loss | Lose about 0.25 kg a week | −275 |
| Maintain weight | Hold steady at your current weight | No change |
| Gradual weight gain | Gain about 0.25 kg a week | +275 |
| Steady weight gain | Gain about 0.5 kg a week | +550 |
Switch the calculator to imperial units and the rates become 0.5, 1 and 2 lb a week, which work out at 250, 500 and 1,000 calories a day. Those are the round numbers most people have heard, and they are close enough to their metric equivalents that the difference does not matter.
Choosing your activity level honestly
This is the single largest source of error in the result, and it is entirely within your control. The gap between sedentary and moderately active is around 500 calories a day for a typical adult — enough to turn a deficit into maintenance without you doing anything wrong.
Most people choose one level too high. Two rules help:
- Describe an ordinary week. Not the week you have planned, and not your best month last year. If you train three times a week in theory and once in practice, you train once.
- Count your job before your gym. Eight hours on your feet moves far more energy than forty minutes on a treadmill. A nurse, a warehouse picker or a parent of a toddler is not sedentary because they skipped a session.
If you are genuinely unsure, take the lower option. An estimate that is slightly too low reveals itself gently — you lose a bit faster than planned. One that is too high looks exactly like a plan that is not working.
Eating in a deficit
A deficit of 500 calories a day is the figure most guidelines settle on, and it is a reasonable default: fast enough to see movement within a fortnight, slow enough to keep most of your muscle and most of your sanity. Larger deficits do work, but they cost more — more hunger, more muscle lost alongside the fat, and a much higher chance of abandoning the whole thing.
Three things matter more than the exact number:
- Protein. Keeping intake high during a deficit is what decides whether the weight you lose is mostly fat or partly muscle. It is also the most filling of the three macronutrients, which makes the deficit easier to hold.
- Resistance training. Same reason. A deficit tells your body to shed tissue; lifting tells it which tissue to keep.
- A deficit you will actually keep. 300 calories a day sustained for six months beats 900 abandoned in three weeks, every time.
Expect the first week to look dramatic and mean little — most of it is water and the food currently in transit. Judge the plan on weeks three and four.
Eating in a surplus
Gaining is the same arithmetic pointed the other way, but the sensible rates are much smaller. Your body can only build muscle so fast, and anything beyond that ceiling is stored as fat regardless of how you train.
A surplus of 250 to 300 calories a day — the gradual row in the calculator — is enough for almost anyone. A trained lifter might gain a couple of kilos of muscle in a good year; a beginner rather more. Eating for a kilogram a week does not accelerate that, it simply adds fat you will have to lose again. Pair the surplus with progressive resistance training and adequate protein, or the surplus is just a surplus.
How low is too low
The calculator will not show a target below 1,200 calories a day for women or 1,500 for men. When the arithmetic asks for less — which happens to smaller and older people choosing an aggressive rate — it holds at the floor and says so.
Those are the conventional limits for dieting without medical supervision. Below them it becomes difficult to get enough protein, iron, calcium and B vitamins from food, and the risks — muscle loss, gallstones, disrupted menstrual cycles, persistent fatigue — start outweighing the speed. Very low calorie diets do have a legitimate clinical use, but they are prescribed, monitored, and nutritionally engineered in ways a calculator cannot be.
If your goal genuinely needs an intake below the floor, the answer is a slower rate, not a smaller number — or a referral to a registered dietitian who can supervise something faster.
Why the number stops working
A plan that works for six weeks and then stalls has not failed; it has gone out of date. Three things move underneath it.
- You are smaller. A lighter body costs less to run and less to move. Ten kilograms down, your maintenance figure is around 150 calories lower than when you started.
- Adaptive thermogenesis. Sustained restriction lowers energy expenditure by more than the weight loss alone explains — partly a genuine metabolic slowdown, partly a quiet reduction in fidgeting and spontaneous movement you never notice making.
- Tracking drifts. Portions grow, oil goes unlogged, weekends get rounded down. Self-reported intake underestimates real intake by 20 to 30 per cent in study after study, and it gets worse the longer the tracking goes on.
The fix is the same in all three cases: treat the estimate as a starting position and let the scale correct it. Weigh yourself on the same schedule for three or four weeks, take the average rather than any single reading, and move your intake by 100 to 200 calories in whichever direction the trend asks for. That loop measures you. No equation does.
Frequently Asked Questions
How many calories should I eat a day?
It depends on your size, age, sex and how much you move, which is what the calculator above works out. As a rough anchor, most adult women maintain their weight somewhere between 1,800 and 2,200 calories a day and most adult men between 2,200 and 2,800, but the range within those groups is wide enough that the average is not much use to any individual.
How many calories do I need to cut to lose a kilogram a week?
Around 1,100 calories a day, since a kilogram of body fat holds roughly 7,700 calories. That is a very large deficit and most people should not attempt it — half a kilogram a week, which needs about 550 calories a day, is the rate most guidelines recommend. In imperial terms, a pound a week takes a deficit of about 500 calories a day.
Is eating 1,200 calories a day safe?
1,200 calories is the conventional floor for women dieting without medical supervision, and 1,500 for men — not a target to aim for. Below those levels it becomes hard to get enough protein, iron, calcium and B vitamins from food, and muscle loss accelerates. If your goal appears to need less than that, slow the rate down or work with a registered dietitian rather than cutting further.
What is TDEE?
Total daily energy expenditure — everything your body spends in twenty-four hours. It is your basal metabolic rate plus the energy used digesting food plus all your movement, from formal exercise down to fidgeting. TDEE is the maintenance figure this calculator reports, and the number every goal target is measured from.
Why am I not losing weight even though I am in a deficit?
Usually one of three things. The activity level was set too high, so the deficit is smaller than it looks. Intake is being under-recorded — self-reported eating runs 20 to 30 per cent below actual in study after study. Or you have been dieting long enough that your maintenance has fallen underneath you. Recalculate at your current weight, take a lower activity level, and judge the result on a four-week average rather than a single weigh-in.
Should I eat back the calories I burn during exercise?
Not if you selected an activity level that already accounts for your training — doing both counts it twice, which is one of the most common reasons a deficit quietly disappears. Fitness trackers also tend to overstate calories burned, sometimes substantially. Pick the activity level that describes your normal week and leave the daily target where it lands.
How accurate is this calculator?
The underlying equation lands within 10 per cent of measured resting expenditure for roughly 70 per cent of people, and the activity multiplier adds error on top of that. Treat the result as a starting point with a margin of a few hundred calories, then let four weeks of weight data correct it. Your own trend line beats any equation.
Do I have to count calories to lose weight?
No. A deficit is what causes weight loss, but counting is only one way to create one — portion control, cutting liquid calories, raising protein and eating more whole foods all work without a food diary. Counting is a useful measuring tool, particularly at the start, and a poor long-term habit for some people. The number above is worth knowing whether or not you track against it.
References
- Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990; 51(2):241-247.
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press, 2005.
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. The Lancet, 2011; 378(9793):826-837.
- Lichtman SW, Pisarska K, Berman ER, et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. New England Journal of Medicine, 1992; 327(27):1893-1898.
- National Institute for Health and Care Excellence. Obesity: identification, assessment and management. Clinical guideline CG189, 2014.