Sweat Rate Calculator

Body weight immediately before the session, in kilograms, ideally nude and dry. The before/after difference is the core of the sweat-loss estimate.

Body weight immediately after the session, toweled off and before eating or drinking. Weighing in sweat-soaked clothes hides a large part of the loss.

Everything you drank during the session, in milliliters. It is added back to the weight change, because drinking masks sweat loss on the scale.

A standard bottle is about 500 ml.

Urine passed during the session, in milliliters — usually 0. It left your body but was not sweat, so it is subtracted from the estimate.

Length of the session, as h:mm:ss. Total sweat loss is divided by this to give the rate in liters per hour.