How the calculation works

The formula is: weight loss % = ((starting weight − current weight) ÷ starting weight) × 100. So if you started at 90 kg and now weigh 82 kg, you have lost 8 kg, which is (8 ÷ 90) × 100 = 8.9% of your starting weight.

Expressing loss as a percentage lets you compare progress fairly between people of very different sizes, and it is the measure used in clinical weight-management research and TV-style weight-loss challenges alike.

Why percentage matters more than the scale

Health guidelines focus on percentage because the benefits scale with it. Losing just 5% of your body weight can lower blood pressure, improve blood sugar control and reduce cholesterol; losing 10% brings even larger improvements and can put some cases of type 2 diabetes into remission. You do not have to reach an "ideal" weight to gain real, measurable health benefits.

The calculator above flags these milestones for you — 5% (clinically meaningful) and 10% (significant) — so you can see how close you are to the thresholds that matter most.

Setting a healthy pace

A safe, sustainable rate of loss is generally 0.5–1 kg (1–2 lb) per week, or roughly 0.5–1% of body weight. Faster loss is more likely to come from water and muscle and tends to rebound. Weigh yourself under consistent conditions — same time of day, similar clothing — and expect normal day-to-day fluctuations of a kilo or more from water and food. Watching the weekly trend is far more useful than reacting to a single reading.

Frequently asked questions

Sources & references