At 1 lb/week
80weeks
about 18.4 months
At 2 lb/week
40weeks
Daily deficit
500kcal
for 1 lb/week
Total deficit
280,000kcal
rough rule
Show the math
Weeks = 80 lb ÷ 1 lb/week = 80 weeks
How long to lose 80 pounds
| Pace | Weeks | Months | Daily deficit (kcal) |
|---|---|---|---|
| 0.5 lb/week | 160 | 36.8 | 250 |
| 1 lb/week | 80 | 18.4 | 500 |
| 1.5 lb/week | 53 | 12.3 | 750 |
| 2 lb/week | 40 | 9.2 | 1,000 |
Why it's rarely a straight line
The 3,500-calorie rule overstates long-run loss because your burn falls as you get lighter. Expect faster early weeks (partly water) and a slower finish. The NIH Body Weight Planner models this more precisely. More: calorie deficit basics.
How to use it
- Enter your numbers. Switch between US and metric units at any time.
- Results update as you type, and the formula is shown so you can check it.
- Copy the link, save the plan on this device, or print it for your next appointment.
Want a clinician to look at these numbers?We know licensed clinicians in every state. If you ask, one can reach out to you. Get matched
These are estimates, not a diagnosis. A clinician can account for your health history and medicines.
Other goals
Common questions
How long does it take to lose 80 pounds?
About 80 weeks at 1 lb a week, or 40 weeks at 2 lb a week. Loss usually slows over time.
Can you lose 80 pounds in a month?
Only small amounts are realistic for most people; about 4 to 8 lb a month is a common healthy pace.