Free tool
Calorie deficit calculator that stays honest
Find your maintenance, choose how hard you want to push, and see the daily target and the weekly fat-loss rate it implies. Then see why the number needs to move as you do, and how FORM handles that for you.
A deficit means eating below maintenance. Around 7,700 kcal roughly equals a kilo of fat, so the daily gap sets your weekly rate. Bigger is not better: gentle deficits protect muscle and are easier to stick to. FORM adjusts the number as your real weight trend responds, so you never chase a stale figure.
The one rule
Fat loss is a deficit, whatever the diet is called
Keto, fasting, low-carb, calorie counting: every approach that works does the same thing underneath, it puts you below maintenance. Pick the style you can stick to, but know the deficit is the lever. This calculator gives you the number; the trick is holding it long enough for the trend to show.
Why gentle wins
Smaller deficit, better odds
A punishing deficit loses weight faster on paper and quietly costs you muscle, energy and adherence in real life. A 10 to 20% cut keeps training strong, hunger manageable and the plan livable, so you actually reach the end. Pair it with high protein to hold muscle, and let the weeks do the work.
The moving target
Your deficit shrinks as you do
Lose weight and your maintenance drops, so an intake that was a 500 kcal deficit becomes a 300 kcal one and the scale slows. Most people read that as failure and crash their calories. FORM instead re-reads your smoothed weight trend and nudges the target to keep the deficit real, so progress continues without you living on fumes.
Turn the target into meals
The macro calculator splits your deficit into protein, carbs and fat, and the budget meal planner builds a costed week that hits it.
FAQ
Calorie deficit: FAQ
What is a calorie deficit?
A calorie deficit means eating fewer calories than you burn in a day, which forces your body to use stored energy (mostly fat). It is the one thing every fat-loss diet has in common, whatever it is called. The calculator finds your maintenance, then subtracts a sensible amount.
How big should my calorie deficit be?
A deficit of roughly 10 to 25% below maintenance suits most people. Gentle deficits are slower but protect muscle and are far easier to sustain, which is what actually gets you to the finish. Very large deficits burn out fast and cost you muscle.
How many calories is 1kg of fat?
Roughly 7,700 kcal per kg (about 3,500 kcal per lb). So a 500 kcal daily deficit is around 3,500 kcal a week, or close to half a kilo of fat. It is an approximation, not a guarantee, because water and adaptation move the scale too.
Why am I in a deficit but not losing weight?
Usually your maintenance is lower than a formula estimated, portions crept up, or normal water and glycogen swings are hiding fat loss on the scale. Track a smoothed weight trend over 2 to 3 weeks rather than day-to-day. FORM re-estimates your real maintenance from that trend and adjusts your target so you keep moving.
Should my calorie deficit change over time?
Yes. As you get lighter you burn less, so the same intake becomes a smaller deficit and progress slows. That is normal, not failure. FORM watches your weight trend and nudges the target to keep the deficit honest, instead of leaving you on a number that has gone stale.