The calorie deficit to lose 80 pounds
80 lb is 36.3 kg, and it takes about 280,000 calories of accumulated deficit to shed. How long that takes is entirely a question of how fast you're willing to go.
How long it takes, by pace
| Pace | Daily deficit | Weeks | Months |
|---|---|---|---|
| 0.5 lb/weekSlow and steady | 250 | 160 | 36.8 |
| 1 lb/weekStandard | 500 | 80 | 18.4 |
| 1.5 lb/weekAggressive | 750 | 54 | 12.4 |
| 2 lb/weekVery aggressive | 1,000 | 40 | 9.2 |
- 0.5 lb/week — Easiest to stick to and the least disruptive to training or social life.
- 1 lb/week — The pace most guidance points at. Noticeable progress without white-knuckling it.
- 1.5 lb/week — Workable if you have a lot to lose. Harder to hold past a couple of months.
- 2 lb/week — Only appropriate at higher starting weights, and more of what you lose will be muscle.
A caveat every other calculator skips
Be honest with yourself about the horizon: at a pound a week this is over 18 months. Every calculator on the internet will draw you a straight line to that date, and every one of them is wrong — metabolic adaptation means the last 20 lb take noticeably longer than the first 20. Treat the date as a direction and recalculate monthly.
Why your starting weight changes the answer
The safe pace scales with your bodyweight, not with your goal. Losing 80 lb is a much bigger proportional change for a lighter person, and the sustainable ceiling of about 1% of bodyweight per week moves with them.
| Starting weight | 80 lb is | Safe max pace | Fastest sensibly |
|---|---|---|---|
| 180 lb | 44.4% | 1.8 lb/wk | 45 weeks |
| 200 lb | 40% | 2 lb/wk | 40 weeks |
| 220 lb | 36.4% | 2.2 lb/wk | 37 weeks |
| 250 lb | 32% | 2.5 lb/wk | 32 weeks |
| 280 lb | 28.6% | 2.8 lb/wk | 29 weeks |
| 320 lb | 25% | 3.2 lb/wk | 25 weeks |
Get your actual number
The tables above are the arithmetic of 80 lb in general. Your maintenance depends on your age, height, weight, and how much you move — and that's what sets the target you actually eat to.
Calculate my deficit — freeCommon questions
How long does it take to lose 80 pounds?
At a standard pace of 1 lb per week it takes about 80 weeks — roughly 18.4 months — and needs a daily deficit of about 500 calories. Going faster is possible but the sustainable ceiling is about 1% of your bodyweight per week, so a heavier person can safely lose 80 lb sooner than a lighter person can.
What daily calorie deficit do I need to lose 80 pounds?
It depends entirely on the pace you pick, not on the 80 lb target itself. A pound of fat is about 3,500 calories, so 1 lb per week needs roughly 500 calories a day below your maintenance. The target only changes how long you hold that deficit.
Is losing 80 pounds fast safe?
The limiting factor is your bodyweight, not the goal. Most guidance caps sustainable loss at about 1% of bodyweight per week, and going beyond that means a larger share of what you lose is muscle rather than fat. There is also a floor: never eat below your resting metabolic rate, and generally not below 1,200 calories for women or 1,500 for men.
cutcalc gives general information, not medical advice. Talk to a doctor or registered dietitian before making significant changes to how you eat.