Weight loss percentage calculator
Weight loss percentage is starting weight minus current weight, divided by starting weight, times 100. From 200 lb to 180 lb, that is 10 percent.
Percent changed = (starting weight − current weight) ÷ starting weight × 100
Both weights use the same unit. The unit choice changes the labels and keeps the numbers as typed.
10.0 percent lower
20 lb lower
Pounds changed as a share of starting weight
Every number in these tables is worked out from the printed formula. Table 1 gives percents rounded to one decimal place. Table 2 gives exact amounts in pounds.
| Starting weight | 5 lb | 10 lb | 15 lb | 20 lb | 25 lb | 30 lb |
|---|---|---|---|---|---|---|
| 150 lb | 3.3 | 6.7 | 10.0 | 13.3 | 16.7 | 20.0 |
| 175 lb | 2.9 | 5.7 | 8.6 | 11.4 | 14.3 | 17.1 |
| 200 lb | 2.5 | 5.0 | 7.5 | 10.0 | 12.5 | 15.0 |
| 225 lb | 2.2 | 4.4 | 6.7 | 8.9 | 11.1 | 13.3 |
| 250 lb | 2.0 | 4.0 | 6.0 | 8.0 | 10.0 | 12.0 |
| 300 lb | 1.7 | 3.3 | 5.0 | 6.7 | 8.3 | 10.0 |
| Starting weight | 5 percent | 10 percent |
|---|---|---|
| 150 lb | 7.5 lb | 15 lb |
| 175 lb | 8.75 lb | 17.5 lb |
| 200 lb | 10 lb | 20 lb |
| 225 lb | 11.25 lb | 22.5 lb |
| 250 lb | 12.5 lb | 25 lb |
| 300 lb | 15 lb | 30 lb |
How to calculate weight loss percentage in three steps
The example goes from 200 lb to 180 lb.
- Subtract the current weight from the start. 200 − 180 = 20.
- Divide by the starting weight. 20 ÷ 200 = 0.10.
- Multiply by 100. 0.10 × 100 = 10 percent.
The same pounds can be different percents
A change of 10 lb is 6.7 percent of a 150 lb start, 5.0 percent of a 200 lb start and 3.3 percent of a 300 lb start. Pounds describe the amount. Percent describes its share of the starting weight.
At 10 percent, the amount is 15 lb for a 150 lb start and 30 lb for a 300 lb start. The divisor is what makes the difference.
Percent arithmetic in group challenges
People in a group compare by percent because their starting weights differ. A change of 20 lb from 200 lb is 10.0 percent. The same 20 lb from 250 lb is 8.0 percent.
Different amounts can also give the same percent. A change of 15 lb from 150 lb and a change of 30 lb from 300 lb are both 10.0 percent.
Scale readings change the calculation
Both typed weights are scale readings, so the percent moves when a reading moves. One pound is 0.7 percent of 150 lb, 0.5 percent of 200 lb and 0.3 percent of 300 lb. These numbers describe one pound in the formula, not the size of a daily swing.
The guide to why scale weight jumps from day to day covers those swings. The guide to weigh-in timing, frequency and reading the trend covers how readings fit together.
A percent example on the CDC page
The CDC page Steps for Losing Weight sizes a weight change as a percent of a person's weight. It says "For example, a 5% weight reduction for a person who weighs 200 pounds is 10 pounds." The page is dated January 17, 2025, opened October 11, 2026.
Table 2 gives the same 10 lb for 5 percent of 200 lb.
A clinician is the person to ask about medical questions.
Other calculations use other inputs
This formula uses total body weight only. It has no input for body fat or lean mass. The lean body mass estimate from height, weight and sex and the fat-free mass and FFMI calculation from height, weight and body fat percentage answer separate questions.
The estimate of daily calorie needs uses TDEE. The calorie deficit calculation from TDEE and a chosen weekly rate concerns daily calories rather than the share of a starting weight.
There are also guides on what guidelines say about calorie deficit size and why weight loss plateaus.
Weight history and food logging in TrueCal
TrueCal is a calorie and macro tracker for iPhone, Android and the web. The app has a weight history to review. Manual calorie logging is free. Pro includes macros and logging from a typed description, voice, a photo or a barcode.
The calculator on this page runs in the browser and saves nothing to a TrueCal account.
Divisors, units and weight changes
Why divide by the starting weight?
The starting weight is the base for this percent. A 20 lb change divided by 200 lb times 100 is 10.0 percent. Dividing the same 20 lb by the current weight of 180 lb gives 11.1 percent, which answers a different calculation.
Does this work in kilograms?
Yes. From 90 kg to 81 kg, the amount changed is 9 kg. Dividing 9 by 90 and multiplying by 100 gives 10.0 percent. Both weights must use the same unit.
What if the current weight is above the starting weight?
From 200 lb to 210 lb, the amount changed is 10 lb. That is 5.0 percent gained, using the starting weight of 200 lb as the divisor.
What percent is 10 lb of 200 lb?
10 lb divided by 200 lb times 100 is 5.0 percent.