About the Weight Loss Percentage Calculator
This calculator turns your starting and current weight into the percentage of body weight you have lost. Percentages are fairer than pounds or kilograms for comparing progress between people of different sizes, which is why they are used in weight-loss challenges, workplace competitions and clinical studies.
Add how many weeks you have been going and a goal weight to see your average weekly rate as a percent of body weight, how much is left to lose and how far along you are. It works in pounds or kilograms — the percentages are identical either way.
Clinically, losing 5% of body weight is linked with meaningful improvements in blood pressure, blood sugar and cholesterol for people with overweight or obesity, and a sustainable pace is usually around 0.5–1% of body weight per week. A single weigh-in can swing by 1–2% from water and food, so compare trends rather than individual days.
With the default inputs, the body weight lost is 8%. Change any value above to recalculate instantly.
How to use the weight loss percentage calculator
- 1Choose pounds or kilograms (the percentage is the same either way).
- 2Enter your starting weight and current weight.
- 3Optionally add a goal weight and the number of weeks since you started.
- 4Read your percentage lost, weekly pace and progress toward the goal.
Formula and method
Percentage weight loss divides the weight you have lost by your starting weight, so the result is the same in pounds or kilograms. A negative result means weight was gained.
The weekly figures are simple averages: total loss (in weight units or percent) divided by the number of weeks. Goal progress divides what you have lost so far by the total you set out to lose (start − goal), capped between 0% and 100%.
- Start
- Weight at the beginning of the period
- Current
- Latest weight, measured under the same conditions
- weeks
- Number of weeks between the two weigh-ins
Worked examples
200 lb to 184 lb in 12 weeks
Losing 16 lb from 200 lb is 16 ÷ 200 = 8% of body weight, or about 0.67% per week over 12 weeks. With a 170 lb goal (15% of starting weight), 14 lb remain and the goal is 53% complete.
Workplace challenge in kilograms
Dropping from 92 kg to 87.4 kg is 4.6 kg, which is exactly 5% of starting weight. Over eight weeks that averages 0.575 kg or 0.625% of body weight per week.
Small gain after a holiday
Going from 160 lb to 163 lb is a 3 lb gain, shown as −1.875%. Short-term changes like this are often water and food volume rather than fat.
Frequently asked questions
How do you calculate weight loss percentage?+
Subtract your current weight from your starting weight, divide by your starting weight and multiply by 100. For example, going from 200 lb to 184 lb is 16 ÷ 200 × 100 = 8%.
What is a healthy weight loss percentage per week?+
A commonly recommended sustainable pace is about 0.5–1% of body weight per week, which for most adults is roughly 1–2 lb (0.5–1 kg). Faster loss is more likely to include muscle and be regained.
Why does 5% weight loss matter?+
Research summarised by the CDC and NIH shows that losing 5–10% of body weight can improve blood pressure, blood sugar and cholesterol in people with overweight or obesity, and lower type 2 diabetes risk.
Why use percentage instead of pounds in a weight loss challenge?+
A heavier person can lose more pounds for the same effort. Expressing loss as a percentage of starting weight puts everyone on an equal footing, which is why most challenges rank participants by percent lost.
Why does my weight go up and down day to day?+
Daily weight can shift 1–2% from water, salt, carbohydrate stores, hormones and digestive contents. Weigh at the same time under the same conditions and look at weekly averages.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.
Sources