How Much Water Should Athletes Drink? Hydration for Exercise and Sport

General daily water advice (“8 glasses a day” and similar) isn’t built for training days. Athletes and regular exercisers lose fluid and electrolytes through sweat at rates that vary hugely by intensity, heat, and individual sweat rate, so hydration guidance for exercise is usually broken into before, during, and after phases instead of a single daily number.

Before Exercise

Guidance from the National Athletic Trainers’ Association (NATA) recommends drinking 2–3 cups (roughly 470–710 ml) of water in the two hours before exercise, followed by another 7–10 oz (roughly 200–300 ml) about 10–20 minutes before starting. This gives your body time to absorb the fluid and reach a stable hydration status before you begin, rather than starting already behind.

During Exercise

For every 10–20 minutes of continuous exercise, aim for roughly ¾ to 1½ cups (about 180–350 ml) of fluid. The exact amount depends heavily on sweat rate, heat, humidity, and exercise intensity — someone training hard in summer heat will need considerably more than someone doing a light session indoors.

After Exercise

NATA guidance recommends replacing every pound of body weight lost during exercise with 2–3 cups (about 470–700 ml) of water within the two hours after finishing. This matters more after longer or more intense sessions, where fluid losses are largest.

When Plain Water Isn’t Enough

For sessions under about an hour at moderate intensity, plain water is generally sufficient for most people. Sports drinks or electrolyte supplementation start to matter more when exercise lasts over an hour, intensity is high, conditions are hot, or you’re a heavy sweater — situations where sodium and other electrolyte losses become significant alongside fluid losses. We cover exactly which electrolytes matter and when in our electrolytes and hydration guide.