Calorie Deficit Calculator
The Calorie Deficit Calculator works out the daily calorie deficit — and, with your maintenance calories, the target intake — needed to reach a goal weight in a chosen timeframe. It flags paces that are faster than the recommended safe rate. The 3,500-calories-per-pound rule (7,700 per kilogram) is a long-standing approximation, not an exact conversion — early weight loss also includes water and glycogen shifts, and the relationship becomes less linear over longer periods as metabolic adaptation and changes in lean mass kick in. The calculator assumes your maintenance calories stay constant across the whole timeframe, but TDEE actually drops as body weight decreases, so holding the same pace late in a diet typically requires a slightly larger deficit than day one's number. Because the safe-pace threshold (2 lb or 1 kg per week) is a general population guideline, individual tolerance varies with starting body-fat percentage — leaner people usually can't sustain as aggressive a deficit without losing muscle.
Based on the common estimate that 1 lb of fat ≈ 3,500 calories. Add your maintenance calories (try our TDEE calculator) to see your target intake. General guidance only — not medical advice.
How This Tool Works
Choose US or metric units, enter your current weight, goal weight, and timeframe, and optionally your maintenance calories. You’ll see the daily deficit needed, your target intake, and a warning if the pace is too aggressive.
Formula & Method
About 3,500 calories ≈ 1 lb of fat (7,700 ≈ 1 kg). The daily deficit is the total calories to cut divided by the number of days. Subtracting that from your maintenance calories gives your target daily intake.
Example Calculation
Say you want to lose 15 lb in 10 weeks, with a maintenance level of 2,200 cal/day. Total calories to cut = 15 lb × 3,500 cal/lb = 52,500 calories. Spread over 10 weeks (70 days): daily deficit = 52,500 ÷ 70 = 750 cal/day. That's a pace of 15 ÷ 10 = 1.5 lb/week, under the calculator's 2 lb/week caution threshold, so no aggressive-pace warning appears. Target intake = maintenance − deficit = 2,200 − 750 = 1,450 cal/day.
Frequently Asked Questions
How big a calorie deficit is safe?+
Most guidelines suggest losing about 1–2 lb (0.5–1 kg) per week, which usually means a 250–1,000 calorie daily deficit. Faster than that is harder to sustain and can cost muscle — the calculator warns you if your pace is aggressive.
Do I need my maintenance calories?+
It’s optional — without it you still get the deficit you need. Add your maintenance (from our TDEE calculator) to also see the exact calories to eat per day.
Is this medical advice?+
No — it’s a general estimate based on the standard 3,500-calorie-per-pound rule. Real results vary; consult a professional before starting a significant diet.
Why does losing 1 kg require a bigger calorie deficit than losing 1 lb?+
It's not a different biological rule — a kilogram is about 2.2 times heavier than a pound, so the calculator scales the same underlying rule of thumb: about 3,500 calories per pound of fat becomes roughly 7,700 calories per kilogram (3,500 × 2.20462 ≈ 7,716, rounded to 7,700 here). The unit conversion is carried through the whole calculation, not just the final answer.
What counts as too aggressive a pace?+
In U.S. units, the calculator flags any pace faster than 2 lb/week as aggressive; in metric units, the threshold is 1 kg/week. Crossing it triggers a warning suggesting a longer timeframe, since faster rates are harder to sustain and more likely to cost muscle along with fat.
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<a href="https://everyfix.net/tools/calorie-deficit-calculator/">Calorie Deficit Calculator</a> by <a href="https://everyfix.net">EveryFix</a>Related Tools
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