Calorie Needs Calculator

Enter your personal data and activity level to estimate your daily calorie needs (Total Daily Energy Expenditure) using the Mifflin‑St Jeor equation.

The formula

Men: BMR = 10 × kg + 6.25 × cm − 5 × age + 5
Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161
Daily calories (TDEE) = BMR × activity multiplier
BMR
Energy used at complete rest, before any movement is counted.
Activity multiplier
1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active, 1.9 extra active.
TDEE
The intake at which body weight tends to hold steady.

Worked example

A 41-year-old man, 90 kg, 180 cm, with a desk job and no regular training (1.2).

BMR 1,825 kcal/day, maintenance around 2,190 kcal/day.

Maintenance first, goal second

The figure this returns is a maintenance estimate — what to eat to stay where you are. Any goal is an adjustment applied on top of it, and the page suggests moving roughly 250 to 500 kcal in either direction. A smaller adjustment takes longer and is far easier to hold; a larger one is difficult to sustain and tends to be abandoned before it produces a result. Neither number is a rule, and the right size of change is the one you can still be doing in three months.

Why two people with the same inputs get different real results

Mifflin-St Jeor takes weight, height, age and sex, and nothing else. It cannot see body composition, so a muscular person and a sedentary person of identical weight receive identical estimates even though their actual resting expenditure differs. It also cannot see how much you move without planning to — fidgeting, walking, standing at work — which varies enormously between people and is a large part of why the same target produces different outcomes.

Test the estimate against reality

The strongest version of this number is not the one the equation gives you, it is the one your own data gives you. Eat at the estimate for two to three weeks, weigh yourself under consistent conditions, and use the weekly average rather than daily readings, which move with water and food volume. If weight is stable, the estimate was right for you. If it drifts, adjust by 100 to 200 kcal and repeat. That loop is more accurate than any formula.

Units and inputs

Kilograms and centimetres. Pounds divided by 2.205 gives kilograms; inches multiplied by 2.54 gives centimetres. Entering imperial figures produces a result that is wrong by a wide margin rather than slightly off, so it is usually obvious — but check anyway if the number looks implausible.

Common questions

How many calories do I need to lose weight?

Fewer than your maintenance figure, and the size of the gap sets the pace. The page suggests an adjustment of roughly 250 to 500 kcal from the maintenance number this tool returns. Anything larger is harder to sustain and, past a point, takes more from training quality and daily energy than it gives back in speed.

Is BMR the same as the calories I burn in a day?

No. BMR is only the resting component. Everything else — moving around, working, training, digesting food — is captured by the activity multiplier, and for most people that adds between 20 and 90 percent on top. Eating at BMR rather than TDEE is a far larger deficit than most people intend.

Which activity level fits a desk job with three gym sessions a week?

That combination sits around the lightly to moderately active range, but the honest answer depends on the rest of the week — commute, steps, whether you are on your feet at home. When two options look equally defensible, choose the lower one and let real weight data correct it upward if it is too conservative.

Does age really change the result that much?

The equation subtracts 5 kcal for each year, so a decade is 50 kcal a day — real but modest. Larger age-related changes in expenditure usually come from losing muscle and moving less rather than from age itself, and neither is an input here.

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