As the graphic points out, general guidelines are to drink 17 to 20 ounces (500-600ml) of water 2 to 3 hours before exercising, another 8 ounces (250ml) glass during your warm-up (or 20 to 30 minutes before exercising), 7 to 10 ounces (200-300ml) every 10 to 20 minutes during exercise, and 8 ounces (250ml) of water within 30 minutes after exercising. Yes, that’s a lot of water!
How much you need to drink, however, depends on your age, gender, height, weight, exercise intensity, and how long you exercise. People who sweat a lot may need to drink more. The graphic includes example water amounts for men and women and several other hydration tips. For a more accurate calculation, check out CamelBak’s Hydration Calculator which takes into account the colour of your pee.
Lifehacker / Camelback