Calorie Deficit Calculator
Quick answer: Eating 500 calories a day below your maintenance (TDEE) loses about 1 lb a week, since a pound of fat holds roughly 3,500 calories — but don't go below about 1,200 calories (women) or 1,500 (men).
A calorie deficit is just eating a bit below what your body burns. Enter your details, pick how fast you want to lose, and we'll give you a daily calorie target — add a goal weight and we'll estimate the date you'll hit it.
Deficit size vs. weight loss pace
| Daily deficit | Weekly loss | Monthly loss |
|---|
| 250 calories | ~0.5 lb | ~2 lb |
| 500 calories | ~1 lb | ~4.5 lb |
| 750 calories | ~1.5 lb | ~6.5 lb |
| 1,000 calories | ~2 lb | ~8.5 lb |
How it works
First we estimate your maintenance calories (TDEE) with the Mifflin–St Jeor equation and an activity factor. Your chosen pace then sets the deficit: each pound per week of loss needs roughly a 500-calorie daily deficit, since a pound of fat stores about 3,500 calories. Eating at the resulting target loses weight at that pace; add a goal weight and the tool divides the pounds to lose by your weekly rate to project a finish date. Expect the real number to drift — needs fall as you get lighter, so re-run the calculation every 10–15 lb.
Frequently asked
What is a calorie deficit?
Eating fewer calories than your body burns in a day (your maintenance, or TDEE). Since a pound of body fat stores roughly 3,500 calories, a 500-calorie daily deficit works out to about a pound a week.
How big should my deficit be?
500 calories a day (about 1 lb a week) is the sweet spot for most people — meaningful progress without constant hunger. Bigger deficits work short-term but are harder to sustain and cost more muscle.
Why won't the calculator go lower?
We cap targets at about 1,200 calories for women and 1,500 for men. Below that it's hard to get adequate nutrition, and faster loss should happen under medical guidance.
Why has my weight loss stalled?
Usually the deficit shrank: you weigh less (so you burn less), you're moving less without noticing, or portions crept up. Re-run the calculator at your current weight and tighten up tracking for a week before changing anything drastic.
Should I eat back exercise calories?
Mostly no — your activity level here already includes your exercise, and fitness trackers overestimate burn. Pick the honest activity level, eat your target, and judge by the scale trend over two weeks.
Is this medical advice?
No — it's a general estimate for healthy adults. Talk to a doctor before dieting if you're pregnant, have a medical condition, or have a history of disordered eating.
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