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Weight Loss Percentage Calculator
Enter your starting and current weight to see what share of your body weight you have lost — and, with a goal, how far along you are.
Short answer
Subtract your current weight from your starting weight, divide by your starting weight and multiply by 100. Going from 220 lb to 205 lb is 15 ÷ 220 × 100 = 6.8%. Losing 5–10% of starting weight is where the CDC says health benefits are likely to begin.
Ten pounds means something different on a 150 lb frame than on a 300 lb one. Expressing loss as a share of where you started puts both on the same scale — which is why clinical trials, doctors and office weight-loss challenges all use it.
It is also a kinder number to track. The first 5% is often the hardest stretch of a plan, and it is also the one that matters most for health.
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Weight Loss Percentage Calculator
The share of your starting weight you have lost, how far you are toward your goal, and where the 5% and 10% milestones fall.
Why 5% matters
6.8% down. Keep the line moving.
SlimAI charts your weight against your goal on the Body tab, next to your BMI and body-fat trend, and the calorie target updates as your weight does.
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Day-to-day scale readings swing by a kilogram or more with water, salt and digestion. Use a weekly average for the current weight if you can. Not medical advice.
Milestones That Matter
Each one is a percentage of your starting weight, not a number of pounds.
5%
Where health benefits such as better blood pressure, cholesterol and blood sugar are likely to begin. 11 lb from a 220 lb start.
10%
A common target in clinical programmes, and the upper end of the range the CDC describes as likely to bring health benefits. 22 lb from 220.
Keeping it
Maintaining a loss is its own skill. Holding 10% for a year is worth more than reaching 15% and regaining it.
Why percentage beats pounds
A 300 lb person who loses 15 lb has lost 5%; a 150 lb person who loses 15 lb has lost 10%. Same pounds, very different achievements. Percentage removes the head start that heavier people get when progress is measured in pounds.
That is why weight-loss challenges rank by percentage, and why research reports outcomes as a share of starting weight rather than a raw number.
One weigh-in is noise. A line is progress.
SlimAI charts your weight against your goal on the Body tab, next to your BMI and body-fat trend, and your calorie target updates as your weight does.
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The 5% and 10% milestones
The CDC says a modest loss of 5–10% of total body weight is likely to produce health benefits, including improvements in blood pressure, blood cholesterol and blood sugar. For many people that is a far smaller number than the goal weight they started with.
Treat 5% as a real finish line rather than a waypoint. It is achievable in a few months at a sensible pace, and it is where the payoff starts.
When the percentage stalls
Weight drifts by a kilogram or more from day to day with water, salt, hormones and digestion. A stall of a week or two is often noise; compare weekly averages rather than individual mornings.
If the weekly average has not moved in three weeks, the usual explanations are portion creep, fewer steps, or a calorie target that has not been updated for your new, lower weight.
Weight Loss Milestones by Starting Weight
Pounds to lose, and the weight you reach, at 5%, 10% and 15% of your starting weight.
| Starting weight | 5% | 10% | 15% |
|---|---|---|---|
| 150 lb (68 kg) | 7.5 lb → 142.5 lb | 15 lb → 135 lb | 22.5 lb → 127.5 lb |
| 180 lb (82 kg) | 9 lb → 171 lb | 18 lb → 162 lb | 27 lb → 153 lb |
| 200 lb (91 kg) | 10 lb → 190 lb | 20 lb → 180 lb | 30 lb → 170 lb |
| 220 lb (100 kg) | 11 lb → 209 lb | 22 lb → 198 lb | 33 lb → 187 lb |
| 250 lb (113 kg) | 12.5 lb → 237.5 lb | 25 lb → 225 lb | 37.5 lb → 212.5 lb |
| 300 lb (136 kg) | 15 lb → 285 lb | 30 lb → 270 lb | 45 lb → 255 lb |
Kilograms work the same way: 5% of 100 kg is 5 kg.
How to Calculate Weight Loss Percentage
One subtraction, one division.
- 1
Take your starting weight
The weight on the day you started, not your highest-ever weight.
- 2
Subtract your current weight
220 lb − 205 lb = 15 lb lost.
- 3
Divide by your starting weight
15 ÷ 220 = 0.068.
- 4
Multiply by 100
0.068 × 100 = 6.8% of your starting weight.
- 5
For progress to a goal, divide by the total you want to lose
Aiming for 185 lb means 35 lb in total; 15 ÷ 35 = 43% of the way there.
The Formulas Behind This Calculator
Computed in your browser. Nothing is uploaded and nothing is stored between visits.
Weight loss percentage
% lost = (start − current) ÷ start × 100A negative result means weight was gained.
Progress to goal
progress = (start − current) ÷ (start − goal) × 100Capped between 0% and 100%.
Milestone weight
weight at n% = start × (1 − n ÷ 100)Shown for 5%, 10% and 15%.
Sources and method
- US Centers for Disease Control and Prevention — Losing weight — States that a modest weight loss of 5 to 10 percent of total body weight is likely to produce health benefits such as improvements in blood pressure, blood cholesterol and blood sugar, and that gradual, steady loss of about 1 to 2 pounds a week is more likely to be kept off.
FAQ
Still Wondering About SlimAI
How do I calculate my weight loss percentage?
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 200 lb to 186 lb is 14 ÷ 200 × 100 = 7%.
Is 5% weight loss significant?
Is 5% weight loss significant?Yes. The CDC says losing 5–10% of total body weight is likely to improve blood pressure, cholesterol and blood sugar. For a 200 lb adult, 5% is 10 lb.
How do weight-loss challenges calculate the winner?
How do weight-loss challenges calculate the winner?Most rank by percentage of starting weight lost, so heavier and lighter participants compete fairly. Use the same scale, the same time of day and similar clothing for every weigh-in.
What is a healthy rate of weight loss per week?
What is a healthy rate of weight loss per week?About 1 to 2 pounds a week, according to the CDC, which is roughly 0.5–1% of body weight for most adults. Faster loss is harder to sustain and more likely to include muscle.
Why did I lose so much in the first week?
Why did I lose so much in the first week?Much of a big first-week drop is water. Eating fewer carbohydrates releases water stored with glycogen, and lower salt intake sheds more. Fat loss runs slower and steadier after that.
Should I use my highest weight as my starting weight?
Should I use my highest weight as my starting weight?Use the weight on the day you started this attempt. If you are tracking a long journey, both are fine — just be consistent and say which one you mean.
Can SlimAI track my weight loss?
Can SlimAI track my weight loss?Yes. SlimAI charts your weight over time on the Body tab of the stats screen, next to your BMI and body-fat trend, and your weight feeds the daily calorie goal so the target keeps up as you lose.
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