Calorie Deficit Calculator
Tell us where you are, where you want to be, and by when. You get the daily calorie target, the required deficit, and honest warnings if the plan is too aggressive to keep muscle.
How to use this calculator
- Enter your stats and activity level — same as the TDEE calculator.
- Set your goal weight and the date you want to hit it. Gaining works too: set a goal above your current weight.
- Read your daily calorie target, and any warnings about pace — then recalculate every 2–3 weeks as your weight changes.
How this calculator works
One kilogram of body weight stores roughly 7,700 kcal (≈3,500 kcal per pound) — a standard approximation. Your required daily deficit follows directly:
daily deficit = (current kg − goal kg) × 7,700 ÷ days until targetdaily intake = TDEE − daily deficitTDEE is estimated with Mifflin-St Jeor × activity factor, exactly as in our TDEE calculator. As you lose weight your TDEE drops, which is why plans stall — recalculate with your new weight every 2–3 weeks.
What pace is safe?
| Weekly rate | Daily deficit | Verdict |
|---|---|---|
| 0.25 kg (0.5 lb) | ~275 kcal | Gentle — best for lean people preserving muscle |
| 0.5 kg (1 lb) | ~550 kcal | The standard, sustainable pace |
| 0.75–1 kg (1.5–2 lb) | 800–1,100 kcal | Aggressive — works if obese, costly if already lean |
A common guardrail: keep the rate under ~1% of body weight per week, and keep intake above roughly 1,200 kcal (women) / 1,500 kcal (men) without medical supervision.
Frequently asked questions
Why did my plan stop working after a few weeks?
Three compounding reasons: your TDEE fell as you got lighter, your body moves less at a lower weight, and adherence drifts. Recalculate with your new weight, and adjust by 100–200 kcal rather than slashing further.
Should I add exercise instead of eating less?
A mix wins. Exercise protects muscle and lets you eat more for the same deficit — but logging workouts as extra food usually double-counts, since the activity multiplier already includes training.
What is the minimum I should eat?
Commonly cited floors without medical supervision are ~1,200 kcal for women and ~1,500 for men. This calculator flags you if the plan dips below them — extend your timeline instead.
Can I use this to gain weight?
Yes — set a goal weight above your current one and the math flips to a controlled surplus. Keep the rate under ~0.5 kg/week so the gain is mostly muscle, not fat.