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Accurate Calorie Calculator
How many calories do you need per day? Type four numbers and pick an activity level — we compute your maintenance calories with the clinically standard Mifflin-St Jeor equation and show honest −500 / +500 kcal targets for losing or gaining about 0.5 kg (1 lb) a week.
Your body stats
Calories per day to maintain your weight
Honest range ±100 kcal: about 1,880–2,080 kcal/day
Mifflin-St Jeor BMR 1,649 kcal/day × activity 1.20 (sedentary)
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Simple targets
A 500 kcal deficit would land below the 1,500 kcal/day floor recommended for men. Don't self-prescribe a deficit that low — talk to a doctor or registered dietitian.
Estimate for average healthy adults (18+). Not medical advice, and less precise for very muscular, pregnant, or under-18 users.
How the calorie number is calculated
Three steps, all in your browser: one BMR formula, one activity multiplier, one honest range.
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 for men, or −161 for women. It is the resting-energy equation dietitians use most, and it is more accurate than the older Harris-Benedict equation.
BMR is multiplied by 1.2 to 1.9 depending on how you actually move. This is the largest single source of error (±20%), which is why every option shows its multiplier.
The result is rounded to the nearest 10 kcal and shown with a ±100 kcal band, because no equation predicts an individual's true expenditure exactly.
What this tool is — and what it isn't
Daily maintenance calories, plus a simple −500 / +500 kcal target for about 0.5 kg (1 lb) per week of loss or gain. Nothing else is asked of you.
No login, no cookie wall, no email capture, no third-party scripts. Your numbers are used in memory and never transmitted or stored.
There are no macros, food databases or meal plans here. Logging food is a different job; this page only sets the calorie ceiling you would log against.
Estimates are for healthy adults 18+. Very muscular, pregnant, under-18 or medically supervised users should get a real measurement instead.
FAQ
Is the Mifflin-St Jeor equation accurate?
It is the standard used by dietitians and is typically within about 10% of a measured value for healthy adults. The ±100 kcal range shown with your result is the honest way to read it — treat it as a solid starting point, then adjust by what the scale does over 2-3 weeks.
Why is 1,200 / 1,500 kcal a hard floor?
Those are the widely used minimums for women and men eating unsupervised. If a 500 kcal deficit drops you below your floor, the tool says so instead of printing an unsafe target — a slower deficit or professional guidance is the better route.
Should I eat back the calories I burn in workouts?
No — the activity multiplier already accounts for your training week. Eating back exercise calories on top of it double-counts them, which is one of the most common reasons a deficit stalls.
Metric vs imperial — does one round differently?
No. Feet and inches are converted to centimetres and pounds to kilograms internally, the equation runs on metric values only, and rounding happens once, at display time. Switching units never changes your answer.
Does this work offline or on an airplane?
Yes. The whole calculator is a single static page with inline JavaScript. After it loads once, it makes no further network requests and keeps computing normally with no connection.
How fast does the result update?
Immediately on a button or dropdown change, and about 150 ms after you stop typing in a number field, so the big number never flickers mid-entry. Invalid entries keep your last valid result on screen and flag only the field that needs fixing.