Free body composition & weight tool
Weight Loss Percentage Calculator
To calculate weight loss percentage, subtract your current weight from your starting weight, divide by the starting weight, and multiply by 100. Going from 220 lb to 198 lb is 22 ÷ 220 × 100 = 10% lost. Add a goal weight and the calculator also shows how far along you are: with a 170 lb goal, 22 of the 50 lb is 44% of the way there.
Prepared by Prospyr · Reviewed October 3, 2026 · Free, no sign-up, runs in your browser
Adds percent to goal and a progress bar.
Adds the average change per week.
Weight lost so far
10%of starting weight
Down 22 lb, from 220 lb to 198 lb.
Goal as % of start
22.7%
50 lb total
5% of start
209 lb
11 lb lower
10% of start
198 lb
22 lb lower
Arithmetic on the numbers you enter. It does not predict future weight or advise on treatment.
Weight loss percentage formula
Three numbers are enough, and the same formulas work in pounds or kilograms.
- Percent lost: (start − current) ÷ start × 100
- Percent to goal: (start − current) ÷ (start − goal) × 100
- Weight remaining: current − goal
- Average per week: (start − current) ÷ weeks
Percent lost uses the starting weight as the base, so it does not change if you move the goal. Percent to goal uses the distance to the goal as the base, so it does.
Worked example: percent lost and percent to goal
A patient starts at 220 lb, weighs 198 lb after 12 weeks, and has a goal of 170 lb.
| Measure | Math | Result |
|---|---|---|
| Weight lost | 220 − 198 | 22 lb |
| Percent lost | 22 ÷ 220 × 100 | 10% |
| Total to lose | 220 − 170 | 50 lb |
| Percent to goal | 22 ÷ 50 × 100 | 44% |
| Still to go | 198 − 170 | 28 lb |
| Average per week | 22 ÷ 12 | 1.8 lb |
The 5% and 10% milestone weights come from the starting weight too: 220 × 0.95 = 209 lb and 220 × 0.90 = 198 lb.
Weight loss calculator: reading 5% and 10% milestones
Percent of body weight is the unit most clinical programs and studies use because it compares people of different sizes. The CDC notes that even modest weight loss can help improve blood pressure, cholesterol and blood sugar, and gives 5% of a 200 lb body weight (10 lb) as its example. The calculator shows the 5% and 10% weights so you can see where those marks fall.
This is a tracking tool. It does not say what a person should weigh or how quickly they should lose.
For practices that track patient weight
Weight management and body contouring practices often report progress as percent of starting weight. Keep the starting weight and each follow-up in the chart, and the percentage is one division. Prospyr's analytics and charting keep visit data in one place, and the med spa software page shows how the rest fits together.
To work out calorie needs, see the TDEE calculator and the protein intake calculator.
Frequently asked questions
How do I calculate weight loss percentage?
Weight loss percentage equals (starting weight − current weight) ÷ starting weight × 100. If you started at 180 lb and now weigh 171 lb, that is 9 ÷ 180 × 100 = 5%. The units cancel, so pounds and kilograms give the same percentage.
What is the difference between percent lost and percent to goal?
Percent lost compares what you have lost with your starting weight. Percent to goal compares what you have lost with the total you set out to lose. At 220 lb with a 170 lb goal, losing 22 lb is 10% of body weight but 44% of the way to the goal (22 ÷ 50).
How much weight is 5% of body weight?
Multiply your starting weight by 0.05. For a person who starts at 200 lb, 5% is 10 lb. The CDC uses this same example when it says a 5% reduction may lower the risk of some chronic diseases, such as heart disease, prediabetes and type 2 diabetes.
What is a normal rate of weight loss per week?
The CDC says people who lose weight at a gradual, steady pace of about 1 to 2 pounds a week are more likely to keep it off than people who lose weight faster. Enter the number of weeks since you started and the calculator shows your average weekly change so you can compare it with that figure.
Does the calculator work in kilograms?
Yes. Switch the units to kilograms and every result, including the 5% and 10% milestone weights, is shown in kg. Percentages are identical in either unit.
Can this predict when I will reach my goal weight?
No. It reports what has already happened and how much is left. It does not project a date, because weight change slows as weight falls and varies widely between people.
Why is my percentage negative or blank?
If your current weight is higher than your starting weight, the result is shown as a percent gained. Percent to goal needs a goal weight below your starting weight; if the goal is at or above it, only the percent change is shown.
Sources and scope
- CDC. Steps for Losing Weight (cdc.gov)
Gradual, steady loss of about 1 to 2 pounds a week; the example that a 5% reduction for a person who weighs 200 pounds is 10 pounds.
Arithmetic on the numbers you enter. It does not predict results, recommend a weight loss rate or replace advice from the treating provider.