A calorie deficit is the entire physics of fat loss: consistently eat fewer calories than your body burns, and it makes up the difference from stored fat. No supplement, meal timing trick, or “fat-burning” tea changes this equation — it only changes how you feel while following it. The classic rule of thumb, traced back to Max Wishnofsky’s 1958 estimate, is that 1 kg of body fat holds roughly 7,700 kcal. So a daily deficit of about 550 kcal burns roughly 0.5 kg of fat per week. Our free calorie deficit calculator takes your TDEE and your goal and hands you your exact daily calorie target.
Calorie Deficit Calculator
How Deficits Work
- Deficit of ~275 kcal/day → ~0.25 kg/week loss (gentle, easy to sustain)
- Deficit of ~550 kcal/day → ~0.5 kg/week loss (the sweet spot for most people)
- Deficit of ~825 kcal/day → ~0.75 kg/week loss (aggressive; not for beginners)
- Surplus of ~275–550 kcal/day → lean muscle gain when paired with lifting
Bigger isn’t better: deficits beyond ~750 kcal/day for most adults cost significant muscle, tank energy, and trigger the binge-restrict cycle. The best deficit is the smallest one that still moves the scale.
How to Use
- Enter your TDEE (use our TDEE calculator if you don’t know it) — or enter your BMR + activity details.
- Pick your goal: lose 0.25 or 0.5 kg/week, maintain, or gain.
- Click Calculate — your daily calorie target appears.
- Eat at that target for 2 weeks, then weigh: if the scale hasn’t moved, trim another 100 kcal or add 1,500 daily steps.
Worked Example
Fatima’s TDEE is 2,100 kcal. She wants to lose 0.5 kg/week: target = 2,100 − 550 = 1,550 kcal/day. She keeps protein at ~100 g/day (see our protein intake calculator) and lifts three times a week, so most of the weight she loses is fat, not muscle.
Tips & Limitations
- Protein is the deficit’s best friend: 1.6–2.2 g/kg/day preserves muscle and blunts hunger.
- Expect 1–2 kg to drop in week one — that’s mostly water (glycogen depletion), not magic. Real fat loss averages out over weeks.
- Plateaus are normal around weeks 4–6: your TDEE has shrunk with your weight. Re-run the calculator with your new weight.
- Women: menstrual-cycle water swings can hide a month’s progress — compare month-to-month, not week-to-week.
- Never set a target far below your BMR — see our BMR calculator for your floor.
FAQs
How big a deficit is safe?
For most adults, 250–550 kcal/day. More than ~750 kcal/day (or below BMR) risks muscle loss, fatigue, hair shedding, and hormonal disruption — and almost always rebounds.
Why is 1 kg of fat = 7,700 kcal?
It’s Wishnofsky’s classic estimate of the energy stored in adipose tissue. It’s approximate — real bodies vary — but it predicts weight loss remarkably well over weeks.
Do I need to count calories forever?
No. Most people count for 4–8 weeks to learn portions, then maintain by habit and weekly weigh-ins. The calculator gives you the plan; the habits keep it.
Can I lose weight without counting?
Yes — smaller plates, protein at every meal, cutting sugary drinks, and 8–10k daily steps create a deficit without arithmetic. Counting just makes it precise and predictable.
Should I eat back exercise calories?
Usually no — your TDEE already includes typical activity. Eating back a tracker’s (often inflated) burn is the classic way to erase a deficit.