Estimate how much fluid a day needs, adjusted for how long you train and how hot it is when you do.
Estimates are for general guidance only and are not medical advice. For a personalised plan, book a free guided tour at RPM Gym.
The headline figure is total daily fluid, not water you must drink from a bottle. Food contributes roughly a fifth of intake for most people, so the amount you actually pour is lower than the number shown.
The split matters more than the total. The baseline scales with body size; the second figure is replacement for what you sweat out, and it is the part that changes day to day. On a rest day in air conditioning, only the baseline applies.
The sodium figure is there because water alone doesn't restore what sweat removes. Replacing heavy sweat losses with plain water and no sodium is what makes over-drinking risky rather than merely unnecessary.
Daily reference (total water) = EFSA adequate intake … IOM adequate intake men 2.5 L … 3.7 L · women 2.0 L … 2.7 L Sweat replacement (L) = hours × 0.5 … hours × 2.0 Measured instead: sweat loss (L) = pre-mass kg − post-mass kg + fluid drunk L − urine passed L Total = reference + sweat replacement, reported as a range Sodium adequate intake = 1,500 mg/day
An 80 kg person training for 1 hour in hot, humid conditions.
About 3.5 L of total fluid across the day, with roughly 2,200 mg of sodium.
The published adequate intakes for total water are 3.7 litres a day for men and 2.7 for women from the US National Academies, and 2.5 and 2.0 from EFSA. Both include the water in food. An hour of sweating adds somewhere between half a litre and two litres on top, which is a wide range because sweat rates genuinely are.
It's a rough approximation that ignores body size, activity and climate. Eight 250 ml glasses is two litres, which is low for a large person training in Abu Dhabi heat and more than enough for a small, sedentary person in air conditioning.
Yes. Drinking substantially more than you lose, especially without replacing sodium, can dilute blood sodium. It's uncommon, but it is a real risk during long endurance events, and it comes from over-drinking rather than from dehydration.
Urine colour is the practical daily check: pale straw suggests you're keeping up. Losing more than about 2% of body weight across a session is the point at which performance typically starts to drop.
Water is usually enough for short indoor sessions. Sodium matters when sessions run long, when it is hot, or when your skin and kit are visibly salty afterwards, because sweat removes sodium as well as water.
Considerably — heat and humidity raise sweat rate for identical work. The page shows the whole 0.5–2.0 L/hour range rather than picking a hot-weather figure, because where you fall inside it depends on you as much as on the weather. Measuring once tells you more than any climate setting could.
Yes. Caffeinated drinks have a mild diuretic effect but still contribute net fluid. So does food. Fruit, vegetables, soup and yoghurt carry a meaningful share of daily intake.
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