Free tool
How many calories should I eat a day?
Enter your details for a maintenance figure and a sensible target for losing, holding or gaining weight. It is an estimate, not a measurement — the tables further down show what a normal range looks like, and how to correct yours from real-world results.
How the number is worked out
Your BMR — what you burn doing nothing — comes from the Mifflin–St Jeor equation, the same one used in the BetterCal app. Multiplying it by an activity factor gives maintenance, or TDEE.
The loss target is 20% below maintenance rather than a flat 500 calories. A flat deficit is far too aggressive for a small, light person and too gentle for a large one.
Treat the output as a starting point accurate to within a few hundred calories. The real number is whatever holds your weight steady over three weeks.
Reference
Roughly what people need, by age and activity.
Maintenance calories for an average-height adult. Use these to sanity-check the calculator rather than instead of it — your own figure depends on your weight and build.
| Age | Sedentary | Moderately active | Active |
|---|---|---|---|
| Women | |||
| 19–30 | 1,800–2,000 | 2,000–2,200 | 2,200–2,400 |
| 31–50 | 1,700–1,900 | 1,900–2,100 | 2,100–2,300 |
| 51+ | 1,500–1,700 | 1,700–1,900 | 1,900–2,100 |
| Men | |||
| 19–30 | 2,300–2,600 | 2,600–2,900 | 2,900–3,100 |
| 31–50 | 2,100–2,400 | 2,400–2,700 | 2,700–2,900 |
| 51+ | 1,900–2,200 | 2,200–2,400 | 2,400–2,700 |
Subtract roughly 20% from the relevant figure for a weight-loss target, or use the calculator above for something fitted to you.
The honest part
Every one of these numbers is an estimate.
Two people with identical height, weight, age and activity can differ by 300 calories a day in what they actually burn. Prediction equations are fitted to averages, and nobody is average.
So use the figure as a starting point and let reality correct it. Eat at the target for three weeks, track your weight trend rather than any single morning, and adjust by 100–150 calories if the trend is not going where you want. That correction is worth more than any calculator, because it is measured from you rather than predicted about you.
If the weight is not moving despite the arithmetic, this guide works through the causes in order of likelihood — and the answer is usually cooking oil rather than metabolism.
Frequently asked questions
How many calories should I eat a day to lose weight?
Roughly 20% below your maintenance figure, which for most adults lands between 1,500 and 2,200 calories. That produces around half a kilogram of loss a week. Larger deficits work faster and are considerably harder to sustain, which is usually a bad trade.
Is 1,200 calories a day enough?
For most adults it is too low. It is difficult to hit protein and micronutrient needs at that level, and the hunger makes it hard to stick to. Unless it is medically supervised, a slower target you can maintain for months will get you further.
Why is the calculator's number different from another site's?
Different equations and different activity multipliers. Mifflin–St Jeor, Harris–Benedict and Katch–McArdle can differ by 200 calories for the same person, and activity level is self-reported and routinely overestimated. All of them are estimates; none is the truth.
Should I eat back the calories I burn exercising?
Generally no, or at most half. Wearables overestimate active burn substantially — often by 20–40% — and the activity multiplier in the calculation has already accounted for your usual training.
How long before I should change the target?
Three weeks. Weight fluctuates by a kilogram or more day to day from water, salt and digestion, so anything shorter is reading noise. Compare a weekly average against the one three weeks earlier.
Do I need to hit the number exactly every day?
No. The weekly average is what drives weight change. Being 300 over on Saturday and 300 under on Sunday is the same week as two perfectly even days — which is why tracking without obsessing works.
Next step
Now the part that actually takes effort.
Knowing the target is easy. Hitting it means logging food you will actually log. Free to start on iPhone and Android.
