Calorie Deficit Calculator

How a calorie deficit works

You lose weight when you eat fewer calories than you burn — a calorie deficit. Roughly 7,700 calories equals one kilogram of body fat, so a daily deficit of about 550 calories yields around 0.5 kg of loss per week. This tool starts from your TDEE and subtracts the deficit needed for your chosen pace.

Choosing a sensible pace

Faster isn't always better. Aggressive deficits are harder to stick to and risk muscle loss. Pairing a moderate deficit with a high protein intake and resistance training protects muscle while you lean out.

How your target is calculated

The calculator starts from your TDEE (total daily expenditure) and subtracts the deficit needed for the pace you choose. It uses the classic approximation that 1 kg of body fat is about 7,700 kcal (roughly 3,500 kcal per pound):

• Gentle — 0.25 kg/week (0.5 lb) → about 275 kcal less per day
• Steady — 0.5 kg/week (1.1 lb) → about 550 kcal less per day
• Fast — 0.75 kg/week (1.65 lb) → about 825 kcal less per day
• Aggressive — 1 kg/week (2.2 lb) → about 1,100 kcal less per day

Worked example

A man with a 2,430 kcal TDEE at the steady pace: 2,430 − 550 = 1,880 kcal a day. A woman with a 1,850 kcal TDEE at the same pace: 1,850 − 550 = 1,300 kcal. If she chose the aggressive pace, the math would give 750 kcal — and the calculator stops at the safety floor instead.

Why there's a 1,500 / 1,200 kcal floor

Very low-calorie diets are hard to sustain, increase muscle loss and make it difficult to get enough protein, vitamins and minerals. That's why the calculator never suggests less than 1,500 kcal for men and 1,200 kcal for women. If your chosen pace hits that limit, the answer isn't eating less: pick a slower pace or raise your expenditure (more steps, for example).

Which pace to choose

For most people, the gentle or steady pace works best over time. A useful benchmark is losing 0.5% to 1% of body weight per week: people with a lot to lose tolerate faster rates early on; those close to their goal should slow down to protect muscle.

The scale doesn't drop in a straight line

Weight swings 1–2 kg (2–4 lb) day to day from water, salt, carbs and digestion. So:

• Weigh in daily at the same time and compare the weekly average, not a single day.
• The first two weeks usually drop faster (water and glycogen). After that, the rate settles near the plan.
• If the average stalls for 3 weeks in a row, cut 100–150 kcal or add activity.

Losing fat without losing muscle

Three habits do most of the work: high protein (find your range with the protein calculator), strength training at least 2–3 times a week, and enough sleep. If you already lift and want to build muscle while losing fat, body recomposition may suit you better than a flat deficit.

Frequently asked questions