Calculate your sweat rate
Weigh yourself before and after a workout, add the fluid you drank, and this calculator works out how much you sweated and your hourly sweat rate — useful for planning hydration on long runs, rides and hot-weather training.
A 1 kg drop in body weight equals roughly 1 litre of fluid lost. The tool also shows a rehydration target of about 150% of the fluid lost. Everything runs in your browser.