Key Takeaways
- The formula is: percentage weight loss = (starting weight minus current weight) divided by starting weight, then multiplied by 100.
- Example: starting weight 220 lbs, current weight 198 lbs. (220 minus 198) divided by 220 = 0.10. Multiply by 100 = 10 percent weight loss.
- The formula works the same in pounds, kilograms, or any other unit, as long as both weights use the same unit.
- 5 percent weight loss is the minimum threshold most clinical guidelines use for "clinically meaningful" weight loss.
- 10 to 15 percent loss substantially improves type 2 diabetes, sleep apnea, and cardiovascular markers; 20 percent or higher is the GLP-1 medication target.
The short answer
Percentage weight loss equals (starting weight minus current weight) divided by starting weight, multiplied by 100. Example: a 220-lb person who now weighs 198 lbs has lost (220 minus 198) divided by 220, equals 0.10, equals 10 percent. The formula works in any unit as long as both weights use the same unit.
Table of contents
- The 30-second answer
- The percentage weight loss formula explained
- Worked examples in pounds and kilograms
- Quick reference table for common starting weights
- Why percentage matters more than total pounds lost
- Clinical thresholds: 5 percent, 10 percent, 15 percent, 20 percent
- How GLP-1 medications compare on percentage weight loss
- Common mistakes when calculating percentage weight loss
- Calculating percentage of body weight lost during a specific period
- FAQ
- Footer disclaimers
The percentage weight loss formula explained
The formula is straightforward: If you would rather not do the arithmetic by hand, you can run your own numbers in the FormBlends calculator.
Check your GLP-1 eligibility
Use our free BMI Calculator to see if you may qualify for provider-reviewed GLP-1 therapy.
Try the BMI Calculator →Percentage weight loss = ((Starting weight - Current weight) / Starting weight) × 100
Percentage weight loss this period = ((Period start weight - Current weight) / Period start weight) × 100
Related guides
- How to Figure Weight Loss Percentage: The Formula, Chart, and What the Numbers Mean
- How to Calculate Weight Loss Percentage: The Formula That Actually Predicts Long-Term Success
- How Do You Calculate Percentage of Weight Loss: The Formula Clinicians Use (and Why It Matters More Than Pounds)
- How to Calculate Weight Loss Percentage: The Formula Clinicians Actually Use (and Why It Matters More Than Pounds Lost)
- How to Calculate Percentage of Body Weight Loss: The Formula That Actually Predicts Health Outcomes
- How Do You Calculate Your Weight Loss Percentage: The Formula, Context, and Why the Number Actually Matters
Worked examples in pounds and kilograms
Every example below uses the same formula: ((starting weight - current weight) / starting weight) × 100. Nothing else changes.
Pounds. Started at 250 lbs, now 230 lbs. 250 - 230 = 20. 20 / 250 = 0.08. 0.08 × 100 = 8.0 percent.
Kilograms. Started at 102 kg, now 93.5 kg. 102 - 93.5 = 8.5. 8.5 / 102 = 0.0833. 0.0833 × 100 = 8.3 percent. The unit divides out, so pounds, kilograms, and stones all give the same percentage.
One month only. Weighed 212 lbs on the first of the month, 205.5 lbs today. 212 - 205.5 = 6.5. 6.5 / 212 = 0.0307. 0.0307 × 100 = 3.1 percent for that month. For a single period, divide by the weight you began that period at, not your original starting weight.
Quick reference, if you want to know what a given percentage equals in pounds for your starting weight:
| Starting weight | 5 percent | 10 percent | 15 percent |
|---|---|---|---|
| 150 lbs | 7.5 lbs | 15 lbs | 22.5 lbs |
| 180 lbs | 9 lbs | 18 lbs | 27 lbs |
| 200 lbs | 10 lbs | 20 lbs | 30 lbs |
| 220 lbs | 11 lbs | 22 lbs | 33 lbs |
| 250 lbs | 12.5 lbs | 25 lbs | 37.5 lbs |
| 300 lbs | 15 lbs | 30 lbs | 45 lbs |
Each cell is just the starting weight multiplied by 0.05, 0.10, or 0.15.
Frequently asked questions
Do I divide by my starting weight or my current weight?
Divide by your starting weight. Dividing by current weight inflates the answer: from 250 lbs to 230 lbs the loss is 20 / 250 = 8.0 percent, not 20 / 230 = 8.7 percent.
What if my weight went up instead of down?
Use the same formula and read the negative sign as a gain. From 180 lbs to 186 lbs, (180 - 186) / 180 × 100 = -3.3 percent, which is a 3.3 percent increase in body weight.
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