Weight-loss percentage calculator, with GLP-1 trial averages
Enter your starting weight and your current weight, in pounds or kilograms, and the calculator shows how much you have lost or gained and what percentage of your starting weight that is. Below it are the average results of the main trials of GLP-1 medicines for weight, for reference. They describe the people, doses and time studied, not what anyone else should expect.
Change since the start
Enter your starting and current weight to see the change.
(starting weight − current weight) ÷ starting weight × 100
Average results in trials
Trial
Medicine and dose
Average change
Placebo
STEP 1 68 weeks
Semaglutide injection 2.4 mg
−14.9%
−2.4%
SURMOUNT-1 72 weeks
Tirzepatide injection 5 mg
−15.0%
−3.1%
SURMOUNT-1 72 weeks
Tirzepatide injection 10 mg
−19.5%
−3.1%
SURMOUNT-1 72 weeks
Tirzepatide injection 15 mg
−20.9%
−3.1%
STEP UP 72 weeks
Semaglutide injection 7.2 mg
−18.7%
−3.9%
STEP UP 72 weeks
Semaglutide injection 2.4 mg
−15.6%
−3.9%
OASIS 4 64 weeks
Oral semaglutide 25 mg
−13.6%
−2.2%
For reference only. Each figure is the average for the people, dose and time studied, counting everyone who started, whether or not they kept taking the medicine. It is not a prediction or a goal for anyone.
A change in weight is one measure among many. Your prescriber can tell you what your own results mean.
How is weight loss percentage calculated?
The change is divided by the starting weight and multiplied by 100:
Weight loss percentage = (starting weight − current weight) ÷ starting weight × 100
Both weights must be in the same unit. The percentage is the same in pounds and in kilograms, because the unit cancels out. If the current weight is higher than the starting weight, the result is a gain, and the calculator says so. It rounds the percentage and the amount to one decimal place, half away from zero, so 14.95% shows as 15%.
Worked examples
These weights are illustrative.
Worked examples
Starting weight
Current weight
Change
Percentage of the starting weight
100 kg
85 kg
15 kg lost
15% lost
220 lb
198 lb
22 lb lost
10% lost
90 kg
81.9 kg
8.1 kg lost
9% lost
200 lb
170.1 lb
29.9 lb lost
15% lost
180 lb
184 lb
4 lb gained
2.2% gained
85 kg
85 kg
no change
0%
For the first row: (100 − 85) ÷ 100 × 100 = 15%. For the second: (220 − 198) ÷ 220 × 100 = 22 ÷ 220 × 100 = 10%. A gain works the same way with the numbers the other way round: (184 − 180) ÷ 180 × 100 = 2.2%.
Average results in GLP-1 trials
These are the main trials of the medicines approved for weight management, as each paper reports its primary result. Each figure is the average change in body weight for everyone who was randomized, whether or not they kept taking the medicine. The placebo groups took a dummy treatment for the same time.
Average results in GLP-1 trials
Trial
Medicine and dose
Who took part
Duration
Average change, medicine
Average change, placebo
STEP 1
Semaglutide 2.4 mg, weekly injection
1961 adults with obesity, or overweight with a related condition, without diabetes
68 weeks
−14.9%
−2.4%
SURMOUNT-1
Tirzepatide 5 mg, weekly injection
2539 adults with obesity, or overweight with a related condition, without diabetes
72 weeks
−15.0%
−3.1%
SURMOUNT-1
Tirzepatide 10 mg, weekly injection
the same trial
72 weeks
−19.5%
−3.1%
SURMOUNT-1
Tirzepatide 15 mg, weekly injection
the same trial
72 weeks
−20.9%
−3.1%
STEP UP
Semaglutide 7.2 mg, weekly injection
1407 adults with obesity, without diabetes
72 weeks
−18.7%
−3.9%
STEP UP
Semaglutide 2.4 mg, weekly injection
the same trial
72 weeks
−15.6%
−3.9%
OASIS 4
Oral semaglutide 25 mg, daily tablet
307 adults with obesity, or overweight with a related condition, without diabetes
64 weeks
−13.6%
−2.2%
Obesity in these trials meant a BMI of 30 or more. Overweight with a related condition meant a BMI of 27 or more with at least one weight-related condition. Semaglutide 2.4 mg is the usual maintenance dose of Wegovy® injection and 7.2 mg is Wegovy HD. Oral semaglutide 25 mg is the maintenance dose of the Wegovy pill. Tirzepatide for weight management is sold as Zepbound® in the US.
An average hides a spread: in each trial, individual results were above and below it. The trials ran for different lengths of time with different groups of people, so they are shown side by side, not ranked. Which medicine and dose fits a person is a decision for them and their prescriber.
What the percentage can and cannot tell you
It is a simple ratio. It does not say whether the weight lost was fat, muscle or water.
It depends on the starting point you choose. Use the same starting weight each time, for example your weight on the day you started a medicine.
It is not a verdict. Weight changes from day to day with water, food and the time of day. A trend over weeks says more than one weigh-in.
It is not compared with you. The calculator never says whether a result is on track. Your prescriber can tell you what your own change means.
Frequently asked questions
How do I calculate my weight loss percentage?
Subtract your current weight from your starting weight, divide by your starting weight and multiply by 100. From 220 lb to 198 lb: 22 ÷ 220 × 100 = 10%.
Does it matter if I use pounds or kilograms?
No. The percentage is the same in either unit, as long as both weights are in the same one. 100 kg to 85 kg is a 15% loss, and so is 220.5 lb to 187.4 lb, the same weights in pounds.
What does 5% or 10% weight loss mean?
It is the share of your starting weight that is gone. For someone who started at 200 lb, 5% is 10 lb and 10% is 20 lb. Trials often report results as a percentage of the starting weight.
Are the trial results what I will lose?
No. They are averages for the people, doses and time studied, and individual results were above and below them. They are on this page for reference, not as a goal or a prediction.
Why show the placebo results?
The placebo groups took a dummy treatment for the same time, in the same trial. Their average shows how weight changed without the medicine, which is the fair comparison for the medicine's average.