Weight Loss Percentage Calculator — % of Body Weight Lost
Enter your starting and current weight — and optionally a goal weight — to see exactly what percentage of your body weight you have lost and how far you are from your goal.
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15 kg lost from 100 kg starting weight
- 1
Weight lost
100 − 85 = 15Difference between starting weight and current weight. - 2
Weight lost %
15 ÷ 100 × 100 = 15
How does this calculator work?
Percentage weight lost = (starting kg − current kg) ÷ starting kg × 100. For example, dropping from 90 kg to 81 kg is a 10% loss. If you enter a goal weight, progress % = (starting − current) ÷ (starting − goal) × 100. Even 5–10% loss is clinically significant for metabolic health.
Formula
How this is calculated
The percentage of body weight lost is the single most useful metric for comparing weight-loss results across people of different sizes. Because a 10 kg loss means something very different for a 60 kg person versus a 120 kg person, expressing it as a fraction of starting weight normalises the achievement. The formula is straightforward: subtract current weight from starting weight, then divide by the starting weight and multiply by 100.
If you enter a goal weight, the calculator also shows two additional figures. The remaining weight is current weight minus goal weight — how many more kilograms are needed. The progress-to-goal percentage is how much of the total required loss you have already achieved: (starting − current) ÷ (starting − goal) × 100. This can exceed 100% if you have gone past your original goal.
Important context: body weight fluctuates by 1–3 kg throughout the day due to fluid intake, meals, and activity. For the most consistent readings, weigh yourself at the same time each day (typically in the morning, after using the bathroom). A weekly average is more meaningful than a single daily reading. This calculator makes no distinction between fat loss, muscle loss, and fluid loss — all are included in the weight figure.
Frequently asked questions
Subtract your current weight from your starting weight, then divide by your starting weight and multiply by 100. For example: starting 90 kg, current 81 kg → (90 − 81) ÷ 90 × 100 = 10% lost.
It adjusts for starting size. Losing 10 kg from 80 kg (12.5%) is proportionally much more than losing 10 kg from 150 kg (6.7%). Clinical weight-management trials commonly use percentage of initial body weight as their primary outcome for this reason.
Even a 5–10% reduction in body weight is associated with measurable improvements in blood pressure, blood glucose, lipids, and inflammation. Larger losses (10–15%+) produce greater benefits for conditions such as type 2 diabetes and sleep apnoea. Any sustained loss is beneficial — the percentage frame helps set realistic, proportional targets.
Also known as
TG we-Calculate Editorial Team. (2026). Weight Loss Percentage Calculator — % of Body Weight Lost [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/weight-loss-percentage-calculator
TG we-Calculate Editorial Team. "Weight Loss Percentage Calculator — % of Body Weight Lost." TG we-Calculate. 2026. https://we-calculate.com/calculator/weight-loss-percentage-calculator.
TG we-Calculate Editorial Team, "Weight Loss Percentage Calculator — % of Body Weight Lost," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/weight-loss-percentage-calculator
@misc{wecalculate_weight_loss_percentage_calculator, title = {Weight Loss Percentage Calculator — % of Body Weight Lost}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/weight-loss-percentage-calculator}}, year = {2026}, note = {TG we-Calculate} }
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