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Weight Loss Percentage Calculator
Weight loss percentage is your starting weight minus your current weight, divided by your starting weight, times 100. Enter two weights below and this calculator shows your percentage instantly, plus how close you are to the 5 and 10 percent milestones that research links to better health.
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Learn how this works
How to Calculate Weight Loss Percentage
The simple formula for percentage of body weight lost, why it beats tracking kilograms, and what the 5 and 10 percent milestones mean.
Read the guideKey facts about weight loss percentage
- Weight loss percentage equals ((start - current) / start) x 100, and gives the same answer in kilograms or pounds.
- Losing 5 percent of starting body weight measurably improves blood pressure, blood sugar control, and blood lipids in people with overweight or obesity.
- A 10 percent loss is the threshold many clinical guidelines use for meaningful metabolic improvement.
- For a 90 kg starting weight, the 5 percent milestone is 85.5 kg and the 10 percent milestone is 81 kg.
How do you calculate weight loss percentage?
Weight loss percentage puts your progress in the context of your body size. Losing 5 kilograms means something very different for a 60 kg person than for a 120 kg person, and percentage captures that. It also lets you compare your progress against research milestones that are defined in percentage terms.
The formula in plain language
Subtract your current weight from your starting weight, divide the result by your starting weight, then multiply by 100. Because the units cancel out, the formula gives the same answer whether you work in kilograms or pounds. That is why this tool does not need to convert units to find your percentage.
Worked example
Someone starts at 90 kg and is now 85 kg. The math is 90 minus 85, which is 5, divided by 90, which is 0.0556, times 100, giving 5.6 percent. They have crossed the important 5 percent milestone. To reach 10 percent from the same start, they would need to reach 81 kg, a total loss of 9 kg.
Why do the 5 and 10 percent milestones matter?
Studies of people with overweight or obesity consistently find that losing 5 to 10 percent of starting body weight improves blood pressure, blood sugar control, and blood lipids, often before reaching any long term goal weight. Treating these milestones as targets makes progress feel achievable and meaningful. The table shows what each milestone means at common starting weights.
| Starting weight | 5% milestone | 10% milestone | 15% milestone |
|---|---|---|---|
| 70 kg | 66.5 kg | 63.0 kg | 59.5 kg |
| 90 kg | 85.5 kg | 81.0 kg | 76.5 kg |
| 110 kg | 104.5 kg | 99.0 kg | 93.5 kg |
| 130 kg | 123.5 kg | 117.0 kg | 110.5 kg |
To plan the loss itself, set a daily target with the calorie deficit calculator, and if the scale stalls, recheck your maintenance with the TDEE calculator since it falls as you lose weight. If a rigid daily target feels limiting, the calorie cycling calculator spreads the same weekly deficit across high and low days.
When is percentage the wrong lens?
Percentage tracks scale weight, which is not the whole story. If you are lifting weights and building muscle while losing fat, your percentage will understate your real progress. In that case pair this tool with the waist to height ratio calculator for a fuller picture than the scale alone. Percentage also says nothing about rate: losing 10 percent in six weeks and in six months read the same here, but the slower version usually keeps more muscle.
Weigh yourself under consistent conditions, ideally first thing in the morning, and watch the weekly average rather than reacting to daily swings from water and food. Nothing you enter here is stored; it all stays in your browser. Sources are on our methodology page.
Limitations of this calculator
Percentage of body weight lost is a clean, exact calculation, but scale weight is a limited signal. It cannot separate fat from muscle or water, so a training-driven recomposition, a big-carbohydrate meal, or menstrual water retention can all disguise real change. The 5 and 10 percent health milestones come from studies of people with overweight or obesity and may not translate the same way to everyone. Use the number alongside measurements, photos, and how your clothes fit rather than as the only measure of success.
Factors that change your percentage
- Starting weight reference: the percentage is always relative to the start you enter, so use a consistent baseline.
- Muscle versus fat: gaining muscle while losing fat holds weight steady, understating your true progress.
- Water and hormones: sodium, carbohydrate, and menstrual cycle shift scale weight day to day.
- Weigh-in conditions: time of day, food, and clothing affect the reading, so keep them consistent.
- Rate of loss: the percentage says nothing about speed; slower loss usually preserves more muscle.
Sources and references
- Wing RR, et al. Benefits of modest weight loss in improving cardiovascular risk factors. Diabetes Care. 2011. PubMed 21593294
- National Heart, Lung, and Blood Institute. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. nhlbi.nih.gov
- Centers for Disease Control and Prevention. Healthy weight and losing weight. cdc.gov
The percentage formula is documented on the methodology page.
Frequently asked questions
How do you calculate weight loss percentage?
Subtract current weight from starting weight, divide by starting weight, multiply by 100. Going from 90 kg to 85 kg is (90 - 85) / 90 x 100 = 5.6 percent. The formula works identically in pounds because the units cancel.
Why is 5 percent weight loss a common goal?
Research shows losing 5 to 10 percent of starting body weight measurably improves blood pressure, blood sugar control, and blood lipids. It is a realistic first target that delivers health benefits long before any final goal weight.
Is weight loss percentage better than tracking kilograms?
Percentage puts progress in context of your size. Losing 5 kg means something different at 60 kg than at 120 kg. Percentage lets you compare progress fairly over time and against research milestones.
How often should I weigh myself?
Daily weigh-ins under consistent conditions, averaged weekly, filter out water swings best. If daily weighing affects your mood, once a week at the same time works well.
Does this tool store my weight?
No. Everything runs in your browser and nothing is saved or sent anywhere. Refreshing the page clears all inputs.