Free tool
How many calories a day?
This is the same arithmetic the CalorieCounter app runs when it sets your daily target. Nothing you enter is sent anywhere, nothing is stored, and there is no sign-up. Change a field and the number updates.
What does your daily calorie number actually mean?
It is what your body burns on an average day. Part of that is the cost of simply existing, breathing, pumping blood, staying warm, which is the resting number above. The rest is everything you do on top. Multiply the first by a factor for the second and you have your maintenance calories.
Your body spends energy in those two ways: walking to the car, standing at work, training, and fidgeting all sit in the second bucket.
From there, a goal is arithmetic. A kilo of body fat holds roughly 7,700 calories, so losing half a kilo a week means being about 550 calories short each day. Gaining works the same way in reverse, though a surplus adds muscle only if training and protein are there too.
Which formula does this calorie calculator use?
The Mifflin-St Jeor equation, published in 1990 and still the one most dietitians reach for, because it lands closer than the older Harris-Benedict equation for modern bodies. It takes 4 inputs: weight, height, age, and sex. An activity multiplier between 1.2 and 1.9 covers everything else.
It cannot see your muscle mass, your thyroid, your sleep, or your genetics, which is exactly why the result is a starting point rather than a prescription.
The activity multiplier is the blunt part. Five buckets cannot capture the difference between a desk job with a daily hour of lifting and a warehouse shift. If you are between two, pick the lower one, log for a fortnight, and let the trend correct you.
Why will it not show a target below 1,200 calories?
Because under 1,200 calories for women or 1,500 for men it becomes genuinely difficult to get enough protein, calcium, iron and the rest, and hunger stops being something willpower can fix. If a pace would cross that line, the pace disappears from the list and the floor becomes the answer.
Losing slower is not a failure. It is the version you can actually keep doing.
Under 18 the calculator shows a maintenance number only. Growth needs energy, and a deficit is a conversation for a clinician, not a web page.
How do you use a calorie target without obsessing over it?
Treat it as a hypothesis and let 2 or 3 weeks of real data correct it. Watch the weekly trend rather than the daily number, adjust by 100 to 200 calories only if nothing has moved in 3 weeks, keep protein high, and log most days instead of perfect ones.
- Use it as a starting point, not a verdict. Two or three weeks of real data beats any formula.
- Watch the trend, not the day. Weight swings by a kilo or more with salt, sleep, and a full gut.
- Adjust in small steps. If the trend has not moved in three weeks, change by 100 to 200 calories.
- Protein first. It keeps you full and protects muscle while you lose, which is why the split starts at 30 percent.
- Log most days rather than perfect days. Everything you need for that is free.
Is this medical advice?
No. This is arithmetic, and it knows nothing about you beyond the 5 fields above. If you are pregnant or breastfeeding, managing a health condition, taking medication that depends on what you eat, or have a history of disordered eating, talk to a clinician before acting on any number here.
This is arithmetic, not medical advice, and it does not know anything about you beyond the five fields above. If you are pregnant or breastfeeding, managing a health condition, taking medication that depends on what you eat, or have a history of disordered eating, talk to a clinician before acting on any number here. There is a list of places that can help if tracking ever stops feeling good.
What if you want just one part of the maths?
Four smaller tools break this page apart. One gives you resting energy on its own, one gives you the whole day before any goal is applied, one turns a calorie total into grams, and one works out protein from body weight rather than from a percentage. All four run the same arithmetic as this page.
- BMR calculator: resting energy only, before any activity factor.
- TDEE calculator: what you burn on an average day, with no goal applied.
- Macro calculator: a calorie target turned into grams of protein, carbohydrate and fat.
- Protein calculator: grams of protein a day from body weight, training and goal.
FAQ
How many calories should I eat a day to lose weight?
It depends on your body and how fast you want to move. The calculator works out what you burn on an average day, then subtracts an amount that matches your chosen pace. Half a kilo a week is about 550 calories a day off your maintenance number. It will not show you a target below 1,200 calories for women or 1,500 for men, because below that it gets hard to eat enough protein and micronutrients.
Which formula does this use?
Mifflin-St Jeor for resting energy, then an activity multiplier between 1.2 and 1.9 for everything else you do in a day. It is the same calculation the CalorieCounter app runs when it sets your target, so the number here and the number in the app agree.
Why does it refuse some paces?
A fast pace on a small body can push the target under the safety floor. Rather than show a number we would not stand behind, the calculator removes those paces from the list. If every pace is removed, the floor itself is the answer and the weight will come off more slowly.
How accurate is a calorie calculator?
It is an estimate, and every formula of this kind carries a spread of roughly 10 percent for most people, more if you are very muscular, very lean, or older. Treat the number as a starting point. Log for two or three weeks, watch the trend on the scale, and adjust by 100 or 200 calories rather than starting over.
Do I need to eat exactly this every day?
No. Averages over a week matter far more than any single day. A birthday dinner does not undo a week, and hitting the number to the calorie is neither possible nor useful.
Sources
- Mifflin MD et al., A new predictive equation for resting energy expenditure in healthy individuals, American Journal of Clinical Nutrition, 1990
- Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Protein and Amino Acids, National Academies
- Dietary Guidelines for Americans, Office of Disease Prevention and Health Promotion
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