How big should my calorie deficit be?

A deficit of 300–500 calories a day (about 0.5–1 lb per week) is sustainable for most people. Deficits above 1,000/day are hard to maintain and risk muscle loss and nutrient shortfalls.

Calorie Deficit Calculator

Q: What is a calorie deficit?

Eating fewer calories than you burn, forcing your body to use stored energy (mostly fat) to make up the difference. A deficit is the only requirement for weight loss.

Q: Why did my weight loss stall?

As you lose weight, a lighter body burns fewer calories, shrinking your deficit at the same intake. Plateaus also come from water retention, inaccurate tracking, or metabolic adaptation. Recalculate your targets every 10–15 lb.

Set a goal weight and target date, and see the daily calorie deficit — and daily intake — it takes to get there, with a safety check on the pace.

Daily calorie target

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Daily deficit needed

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Weekly loss rate

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Total to lose

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Pace check

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The deficit math

Total deficit = Weight to lose × 3,500 cal/lb (7,700 cal/kg)
Daily deficit = Total deficit ÷ (weeks × 7)
Daily intake = Maintenance − Daily deficit

Worked example

Lose 15 lb in 12 weeks on 2,200 maintenance:

15 × 3,500 = 52,500 cal ÷ 84 days = 625/day deficit → eat ~1,575 cal/day. That's a healthy ~1.25 lb/week pace.

Keeping the deficit sustainable

The best deficit is the one you can actually hold. If the calculator asks you to eat uncomfortably little, extend the timeframe rather than white-knuckling it — slow, steady loss keeps more muscle and rebounds less. Aim to keep the rate under about 1% of body weight per week. Protect muscle with adequate protein and resistance training, and recalculate as you lighten (your maintenance drops, so the same intake becomes a smaller deficit). Track honestly — under-logging is the most common reason a "deficit" doesn't produce loss. Guide: How many calories to lose weight?

Frequently asked questions

What is a calorie deficit?

Eating fewer calories than you burn, so the body uses stored fat. It's the requirement for weight loss.

How big should my deficit be?

300–500/day (0.5–1 lb/week) suits most people; over 1,000/day is hard to sustain.

Why did my weight loss stall?

A lighter body burns less, shrinking the deficit — plus water and tracking noise. Recalculate every 10–15 lb.

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Medical disclaimer: The 3,500-cal-per-pound rule is a useful approximation, not an exact biological law. This is educational, not medical or nutritional advice. Consult a professional before restrictive dieting. Last reviewed: July 2026.