Fitshare
Free, no sign-upCalorie deficit calculatorHow much to eat to lose weight?
A calorie deficit means eating less than your body burns. Enter your details to get how many calories to eat a day at three paces, how many kg a week each one means, and — if you like — when you'll reach your goal weight.
Fill in your details and press Calculate. Your deficit, daily target and pace show up here.
Your result
To maintain your weight (TDEE)
–calories
Pace
Eat per day
–calories
- Daily deficit
- –
- Expected loss per week
- –
- Weekly deficit
- –
- Protein per day
- –
This is an estimate from a formula, not medical advice. If you're pregnant, breastfeeding, have a medical condition or a history of disordered eating, don't start a deficit without a professional.
A deficit only works when you know what you ate. In the app you log a meal in a sentence or a photo, and it counts against your target.
How a calorie deficit is calculated
Step 1: what your body burns (TDEE). Start from BMR with the Mifflin-St Jeor equation, and add daily life and training — exactly as in the TDEE calculator. That's the number of calories that keeps your weight steady.
Step 2: how much to cut. A kilogram of fat is roughly 7,700 calories, so:
Loss per week (kg) ≈ daily deficit × 7 ÷ 7,700
A 500-calorie daily deficit ≈ 0.45 kg a week
The calculator offers three paces — 10%, 20% or 25% below your TDEE — with two safety limits, the same as in the Fitshare app:
- A deficit of at most 900 calories a day, even if your TDEE is very high.
- A safe minimum: the target never drops below 1,200 calories for women and 1,500 for men, and for lean people who train a lot sometimes more, so that after training your body still has enough energy to function. When the minimum caps a pace, the calculator says so.
- Under 18 the calculator doesn't suggest a deficit. A body that's still growing needs a personal plan from a sports dietitian or a family doctor.
Step 3: your goal weight. If you enter a goal weight, the calculator divides the difference by the weekly rate and estimates when you'll get there. In practice loss slows as you get lighter, because a lighter body burns less — so recalculate every few kilograms. And if the goal is below the healthy BMI range, the calculator won't show a timeline.
Not medical advice. Every formula estimates an average, and real people can be 10% or more off. Track your weight for two or three weeks and adjust. If you're pregnant, breastfeeding, have a medical condition, take medication that affects weight or have a history of disordered eating, plan a deficit with a doctor or dietitian.
Questions about a calorie deficit
What is a calorie deficit?
A calorie deficit means eating fewer calories than your body burns in a day (your TDEE). Your body covers the gap from its own stores, mostly fat — and that's how you lose weight. Without a deficit over time there's no weight loss, whatever you eat.
What deficit do I need to lose half a kilo a week?
About 500 calories a day. A kilogram of fat is about 7,700 calories, so a 500-calorie daily deficit is 3,500 a week — about 0.45 kg. For a 30-year-old man, 180 cm and 80 kg, training 3-5 times a week, TDEE is about 2,400, so a 500 deficit is roughly 1,900 calories a day.
What's the largest safe deficit?
Without professional guidance, the calculator suggests no more than 25% below your TDEE and no more than 900 calories a day, and the target never drops below 1,200 calories for women or 1,500 for men. A bigger deficit is harder to sustain, costs more muscle and makes regaining the weight more likely.
Why does weight loss slow down?
A lighter body burns less, so the same menu gives a smaller deficit over time. On top of that, the first weeks also shed water, which is why the start is fast. Recalculate your deficit every 3 to 5 kg, and judge the pace by a two-week average rather than one weigh-in.
How do I lose fat without losing muscle?
Three things: a moderate deficit (not the fastest pace), strength training 2 to 4 times a week, and high protein — about 2 g per kg of bodyweight. Exactly how much protein for your weight and training is what the protein calculator works out.
Is the calculator free? Do I need to sign up?
Free, with no sign-up. The calculation runs in your browser, and the details you enter aren't sent to us or stored. If you want to save the target and count calories against it, open an account in the app, which is free too.
More calculators
A deficit you can stick to
Download Fitshare, save your target, and photograph your next meal. The app counts the calories and protein, and shows your weight trend over the weeks.