Free Calorie Deficit Calculator: Daily Calories to Lose Weight
Choose how fast you want to lose weight and get your daily calorie target, the deficit it requires and how long it will take to reach your goal.
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About this calculator
Weight loss happens when you consistently eat fewer calories than your body uses. That gap is the calorie deficit. This calculator estimates your maintenance calories, subtracts the deficit needed for your chosen weekly loss, and tells you the daily target.
A deficit of roughly 250–750 kcal per day suits most people. Larger deficits increase hunger and muscle loss and are rarely sustainable.
How it works
Maintenance (TDEE) = BMR × activity factor (Mifflin-St Jeor)
Daily deficit = weekly loss (kg) × 7,700 ÷ 7
Target calories = TDEE − daily deficit
The 7,700 kcal per kilogram figure is a standard approximation of the energy stored in body fat. Actual results vary because metabolism adapts as you lose weight.
How to read your result
| Weekly loss | Daily deficit | Who it suits |
|---|---|---|
| 0.25 kg | ≈ 275 kcal | Smaller bodies, near goal, easy to sustain |
| 0.5 kg | ≈ 550 kcal | Most people: the usual recommendation |
| 0.75 kg | ≈ 825 kcal | Higher starting weight, short phases |
| 1 kg | ≈ 1,100 kcal | Only for much higher body weights, ideally supervised |
Keep protein high (see our protein calculator) and lift weights to preserve muscle while losing fat.
Worked example
A 32-year-old man, 90 kg, 178 cm, lightly active, wanting to lose 0.5 kg per week to reach 80 kg.
| Daily calorie target | 2,000 kcal/day Eat about this many calories per day |
| Daily deficit | 550 kcal/day Created through food, activity or both |
| Maintenance calories (TDEE) | 2,554 kcal/day |
| Estimated time to goal | 20 weeks About 4.6 months. Real-world loss slows as you get lighter. |
Frequently asked questions
How big should my calorie deficit be?
Most guidelines suggest 500–750 kcal per day, giving roughly 0.5–0.75 kg per week. Smaller deficits are easier to maintain and preserve more muscle.
Is a 1,000 calorie deficit safe?
It can be for people with a lot of weight to lose, but it is hard to sustain and may cause fatigue and muscle loss. Discuss it with a doctor or dietitian first.
Why did my weight loss stall?
Lower body weight lowers your maintenance calories, and water weight hides fat loss for days. Recalculate every 4–5 kg and judge progress by 2–3 week averages.
Do I have to exercise to be in a deficit?
No, but exercise raises your TDEE, helps keep muscle and improves health. You can create the deficit through food, activity or a mix.
What is the minimum calorie intake?
1,200 kcal for women and 1,500 kcal for men are commonly cited floors for unsupervised dieting.
Limitations and when not to use
Not for under-18s, pregnancy, breastfeeding, eating disorders, or people with diabetes or other conditions that need medical nutrition management. The 7,700 kcal rule is an approximation and overstates speed of loss for people with large amounts to lose.
Sources and references
- Mifflin MD, et al. Am J Clin Nutr 1990;51:241–247.
- Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet 2011;378:826–837.
Last updated: 2026-10-09