"Drink eight glasses" is not the same advice for everyone. Get the real number based on your weight, your training and the weather.
The base is 35 ml per kg of bodyweight - so about 2.4 litres for a 70 kg person. On top of that we add what you sweat out training (roughly 350 ml per 30 minutes), plus more if you are in heat or out in the sun.
It is a rough average, not a rule. A 50 kg woman sitting in air conditioning and a 90 kg man working outdoors need very different amounts. In Indian summer that gap gets wider still. Work out your own number instead.
The simplest check is the colour of your urine. Pale yellow or almost clear means you are fine. Dark yellow means you are behind. Do not wait until you feel thirsty - by then you are already slightly dehydrated. Tea and coffee do count towards the total, though too much of either is not ideal.
Everything on this page is worked out from a formula or from published averages. It has never met you, and it cannot see your blood pressure, your medication or an old injury.
Talk to a doctor before you start if you are pregnant or breastfeeding, have a heart condition, diabetes or high blood pressure, take regular medication, have or have had an eating disorder, are recovering from injury or surgery, or are under 18. Stop and get advice if any exercise causes pain, dizziness or chest discomfort.
More about where these numbers come from is on the about page.
