Free calorie calculator
How many calories do you actually need?
Enter six numbers and get your BMR, your maintenance calories and a daily target for the goal you picked — using the same Mifflin–St Jeor baseline the NutriLog AI Android app starts your plan from. It runs in your browser: no account, no email, nothing sent anywhere.
Want this tracked automatically, every day?
Get it on Google PlayGeneral wellness guidance, not medical advice. If you are pregnant, breastfeeding, under 18, or managing a medical condition, talk to a doctor or a registered dietitian before acting on any calorie target.
How the number is worked out
Three steps, in this order. Nothing here is proprietary — you can check the arithmetic.
1. BMR, from the Mifflin–St Jeor equation
Your basal metabolic rate is what your body spends staying alive with no movement at all:
heartbeat, breathing, temperature, brain. The equation is
10 × kg + 6.25 × cm − 5 × age, then +5 for men and
−161 for women. Mifflin–St Jeor is the default for a reason — it beats the older
Harris–Benedict equation for most people who are neither athletes nor very lean.
2. TDEE, by multiplying for how much you move
Total daily energy expenditure is BMR times an activity factor. This is where most of the error in any calorie estimate lives, so pick the honest option rather than the flattering one:
| Activity level | Factor | Who it fits |
|---|---|---|
| Sedentary | 1.20 | Desk job, no deliberate training |
| Lightly active | 1.375 | 1–3 sessions a week, or a lot of walking |
| Moderately active | 1.55 | 3–5 sessions a week |
| Very active | 1.725 | 6–7 sessions a week |
| Extra active | 1.90 | Physical job, or training twice a day |
3. The goal adjustment
Losing subtracts 500 kcal a day, which is about half a kilo (one pound) of fat a week. Gaining adds 300 — smaller on purpose, because a bigger surplus mostly adds fat rather than muscle. Maintaining changes nothing. The result is then floored at 1,200 kcal for women and 1,500 for men (1,350 if you leave sex unstated): if your goal would push it lower, the calculator says so instead of quietly handing you an unsafe number.
What this number is not
It is an estimate with roughly a 10% spread either way. Two people with identical height, weight, age and sex can genuinely need a few hundred calories more or less than each other — thyroid, medication, sleep, muscle mass and how much you fidget all move it. Nobody's calculator knows any of that.
So treat it as a starting point, not a verdict. Eat to it for two to three weeks, weigh yourself consistently, and adjust against what actually happened. That feedback loop is the part that matters, and it is the part a one-off calculation cannot do for you — it is also what the app keeps up for you: NutriLog AI updates your target as your weight changes, so the number moves with your real data instead of staying on day one's estimate.
Common questions
How many calories should I eat a day to lose weight?
Your maintenance calories minus about 500 a day. Pick the weight-loss goal above and the calculator does it. Below the floor (1,200 kcal for women, 1,500 for men) it stops and tells you, rather than prescribing a deficit that steep.
What is the difference between BMR and TDEE?
BMR is complete rest. TDEE is BMR multiplied by how much you move. You eat against TDEE. Eating at BMR while living a normal life is a large accidental deficit.
Should I eat back the calories I burn exercising?
Not on top of an activity factor — that double-counts. The factor you picked above already includes your training. Only add exercise calories separately if you set activity to sedentary and log every session by hand.
Is this calculator free, and do you keep what I type?
Free, and no. The arithmetic runs in your browser; nothing is sent to a server, so there is nothing for us to keep.
Does the NutriLog AI app give the same number?
The same maintenance number, yes — this page's maintenance figure is the baseline the app starts from. The app then sets the deficit or surplus from the pace you pick — 0.25 to 1 kg a week to lose, up to 0.75 kg a week to gain — instead of this page's fixed 500 below or 300 above, and Build Muscle is a fixed small surplus. The calorie deficit calculator shows the losing numbers. Your target then updates as your weight changes, and with AI Data Sharing on, the app's AI can adjust it by up to 25%, so it follows what your body is actually doing rather than staying on the estimate forever.
Other free calculators
Now let it track the other 364 days.
NutriLog AI keeps this target current — it updates it as your weight changes, and logs the food against it in under a minute. Free, no ads, Android. Free on Google Play.