# What is my weight loss percentage?

Works out the percent of body weight lost from a starting and a current weight, the weight lost, or the weight to reach a percent goal such as the 5% to 10% that NIH suggests.

- Page: https://www.acalculator.org/health/weight-loss-percentage-calculator
- JSON spec: https://www.acalculator.org/health/weight-loss-percentage-calculator.json
- Version: 76fb344849bd

## Default answer

Example with the default inputs (Starting weight 200 lb, Current weight 185 lb): Going from 200 lb to 185 lb is a weight loss of 7.5% (15 lb).

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| start | Starting weight | Your weight before you started losing weight. |
| now | Current weight | Your weight now, or the weight you aim for. |
| pct | Weight loss percentage | The share of the starting weight lost; negative if weight was gained. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| start | Starting weight | Your weight before you started losing weight. |
| current | Current weight | Your weight now, or the weight you aim for. |
| percent | Weight loss percentage | The share of the starting weight lost; negative if weight was gained. |
| lost | Weight lost | The starting weight minus the current weight; negative if weight was gained. |

## Method

Weight loss percentage = (starting weight − current weight) ÷ starting weight × 100.

## Assumptions

- Both weights are measured the same way (same scale, same time of day, similar clothing).
- A current weight above the starting weight gives a negative percent: a gain.

## Worked examples

1. start = 90.718474, pct = 10% gives now = 81.646627, lost = 9.071847. Source: NIDDK (NIH), Your Game Plan to Prevent Type 2 Diabetes: lose 5 to 10 percent of your weight; at 200 pounds a 10 percent goal is 20 pounds, https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-type-2-diabetes/game-plan.
2. start = 90.718474, pct = 5% gives now = 86.18255, lost = 4.535924. Source: CDC, Steps for Losing Weight: a 5% weight reduction for a person who weighs 200 pounds is 10 pounds, https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html.
3. start = 81.646627, now = 77.564295 gives pct = 5%, lost = 4.082331. Source: NIDDK (NIH), Your Game Plan to Prevent Type 2 Diabetes: lose 5 to 10 percent of your weight; at 200 pounds a 10 percent goal is 20 pounds, https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-type-2-diabetes/game-plan.
4. start = 95, now = 85.5 gives pct = 10%, lost = 9.5. Source: NIDDK (NIH), Your Game Plan to Prevent Type 2 Diabetes: lose 5 to 10 percent of your weight; at 200 pounds a 10 percent goal is 20 pounds, https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-type-2-diabetes/game-plan.
5. start = 68.038856, now = 70.76041 gives pct = -4%, lost = -2.721554. Source: CDC, Steps for Losing Weight: a 5% weight reduction for a person who weighs 200 pounds is 10 pounds, https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html.

## FAQ

### How do I calculate weight loss percentage?

Subtract your current weight from your starting weight, divide by the starting weight, and multiply by 100. From 180 lb to 171 lb: (180 − 171) ÷ 180 × 100 = 5%.

### What is 5% or 10% of my body weight?

Multiply your starting weight by 0.05 or 0.10. At 200 lb, 5% is 10 lb (a goal of 190 lb) and 10% is 20 lb (a goal of 180 lb).

### Why does NIH suggest losing 5% to 10%?

NIDDK, part of NIH, suggests a first goal of 5 to 10 percent of your starting weight, for example within 6 months, because even this modest loss can improve blood pressure, cholesterol and blood sugar. CDC says the same about modest weight loss.

### Why use a percent instead of pounds?

A percent compares fairly between people of different sizes. Losing 10 lb is 5% of 200 lb but 8% of 125 lb.

### What does a negative percent mean?

That the current weight is above the starting weight: a gain. From 150 lb to 156 lb is −4%.

### Does the unit matter?

No. The percent is the same in pounds or kilograms, as long as both weights use one unit. 95 kg to 85.5 kg is 10%, the same as 209.4 lb to 188.5 lb.

## Sources

- NIDDK (National Institutes of Health), Your Game Plan to Prevent Type 2 Diabetes: try to lose at least 5 to 10 percent of your current weight; at 200 pounds a 10 percent goal is 20 pounds. Retrieved 2026-10-02. https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-type-2-diabetes/game-plan
- NIDDK, Health Tips for Adults: an initial goal of 5 to 10 percent of your starting weight; at 200 pounds, 10 to 20 pounds. Retrieved 2026-10-02. https://www.niddk.nih.gov/health-information/weight-management/healthy-eating-physical-activity-for-life/health-tips-for-adults
- CDC, Steps for Losing Weight: modest weight loss can improve blood pressure, cholesterol and blood sugar; a 5% reduction for a person who weighs 200 pounds is 10 pounds. Retrieved 2026-10-02. https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html