About the Calorie Calculator
How many calories to eat for a goal. Which is a different question from how many you burn today — that is the TDEE calculator, and this one starts where it finishes.
The difference matters because of a rule that almost every calorie calculator repeats and almost none examines:
The 3,500-calorie rule draws a straight line, and weight loss is a curve.
How to Use the Calorie Calculator
Enter age, sex, height and weight, pick an activity level, and choose a goal.
Body fat percentage is optional — supply it and the resting figure uses Katch-McArdle, which works from lean mass.
Step-by-Step Example
Male, 35, 180cm, 95kg, moderately active, losing 0.5kg a week.
Resting burn: 1,905
× 1.55 for moderate: 2,953 maintenance
− 550 for 0.5 kg a week
──────
Daily intake: 2,403The 550 comes from 0.5 kg × 7,700 calories per kilogram ÷ 7 days. So far this is what every calorie calculator does.
Where the Straight Line Breaks
The 3,500-calorie rule says: a pound of fat is 3,500 calories, so a 500-a-day deficit loses a pound a week, 52 pounds a year, forever.
The arithmetic is fine. The projection is wrong, and it is wrong for a reason that is obvious once stated: it holds your expenditure fixed while your body shrinks.
| After a year at 2,403 calories | Weight |
|---|---|
| 3,500-calorie rule predicts | 68.9 kg |
| Recomputing burn each month | 76.1 kg |
| Difference | 7.2 kg |
Over seven kilograms of difference, from the same intake. And the reason is visible month by month:
month 1: 92.8 kg, deficit now 550
month 3: 88.9 kg, deficit now 485
month 6: 83.8 kg, deficit now 401
month 12: 76.1 kg, deficit now 274You chose a 550-calorie deficit. By month twelve you are running a 274-calorie one — without changing a single thing about what you eat.
The Plateau Is the Plan
This leads somewhere useful rather than merely discouraging.
Every intake has a weight at which your expenditure equals it. Below that you gain, above it you lose, and at it you stop. For this example, 2,403 calories a day settles at about 59.5 kg.
So the honest way to read a calorie target is not "this is my deficit" but:
This is the intake that takes me to X and holds me there.
A plateau is not a failure, a broken metabolism, or evidence that something went wrong. It is the arithmetic finishing. It arrives on schedule whether or not anyone does anything, and knowing where it will arrive turns it from a setback into a milestone.
Breaking through it means eating less again or moving more — not because the plan stopped working, but because it worked and the numbers have changed with you.
Even This Curve Is Optimistic
Worth being straight about.
The adaptive projection accounts for a smaller body burning less. It does not account for metabolic adaptation — the further drop in expenditure that a sustained deficit produces beyond what weight change alone explains.
Real loss is usually slower again than the adaptive figure. Treat it as a ceiling rather than a forecast, and correct against the scale.
Raising Activity Beats Cutting Intake
A practical consequence.
Cutting intake lowers the number you eat. Raising activity lifts maintenance, which widens the deficit and pushes the settling weight down — and it does not run into a floor the way cutting does.
The activity multiplier is also where the leverage is: moving one category is worth around 300 calories on a typical profile, where the choice of BMR equation is worth about 100.
The Floors
The calculator flags intakes below 1,200 for women and 1,500 for men.
These are not hard physiology; they are sensible floors. Below them, adequate protein and micronutrients become genuinely hard to hit, and the body compensates by reducing spontaneous movement — which quietly erodes the deficit you were trying to create.
A slower rate usually reaches the same place more reliably. Anything more aggressive is worth discussing with a doctor or dietitian rather than a calculator.
Understanding Your Result
Daily calories is the intake for your goal.
Against maintenance shows the deficit or surplus.
A year from now runs both projections side by side.
Where it settles gives the plateau weight for this intake.
Worth knowing flags a floor breach or explains what the settling point means.
When Should You Use This Calculator?
Setting a starting intake. As a hypothesis to test, not a prescription.
Before a plateau, not after. Knowing where it lands changes how it feels.
When loss has stalled. Recalculate at your new weight; the number has moved.
To compare goals. The faster rates are not proportionally faster in the long run.
Common Mistakes
Trusting the 3,500-calorie rule as a projection. It is a straight line through a curve.
Reading a plateau as failure. It is the intake arriving where it was always going.
Eating at BMR instead of maintenance. That is an accidental deficit of hundreds.
Not recalculating after losing weight. The old deficit is not the current one.
Going below the floor to hit a date. Slower is usually faster in practice.
Treating any of it as measured. These are estimates on top of estimates.
These are population estimates and can be well out for any individual. Nothing here is medical or dietary advice — speak to a doctor or registered dietitian before making significant changes to what you eat, particularly if you have any medical condition.