Free · No sign-up · Runs in your browser
Percent Weight Gain Calculator
Two weigh-ins in, an exact percent gain or loss out — plus the weekly rate.
Work out your percent change
Not medical advice — this is a math tool, not a health assessment.
How it works
Three steps, no button to press.
Your weight at the first weigh-in, in pounds or kilograms.
The percent change, the gain-or-loss label and the direction track appear instantly.
Type the weeks between weigh-ins to also get a weekly percent and unit rate. Blank hides it.
What the weekly rate means
General pace bands adults commonly see quoted. Your own target is a conversation for a clinician.
Gradual — the slow, easy-to-hold pace most people keep.
Steady — the range usually described as a sustainable rate.
Rapid — often hard to sustain; worth flagging to a clinician.
FAQ
What is the formula for percent weight gain?
(current − starting) ÷ starting × 100. Going from 150 lb to 160 lb is 10 ÷ 150 × 100 = +6.7%.
Does it matter whether I use pounds or kilograms?
No — as long as both weights are in the same unit. The toggle converts the numbers you already typed, so 150 lb becomes 68.0 kg rather than being re-read as 150 kg.
Why does it say “No change” instead of +0.0% gain?
When the two weights match, the change is zero — labelling that a gain or a loss would be misleading, so the result reads 0.0% and “No change”.
How do I get the weekly rate?
Enter the number of weeks between your two weigh-ins. The weekly row appears with a percent-per-week and unit-per-week figure, plus a pace band. Leave it blank and the row is hidden completely.
Are my weights stored anywhere?
No. The whole calculator runs in your browser — nothing is uploaded, logged or saved. This is a math tool, not medical advice.