How much water you actually need depends on your weight, activity level, and climate. This calculator gives you a science-based target in litres, glasses, and per kg of body weight.
The NHS recommends 6–8 cups (1.5–2L) of fluid per day as a baseline, but active adults in warm climates need significantly more. The old "8 glasses" rule is an oversimplification — your needs depend on your size, activity and environment.
About 20% of daily water intake comes from food — particularly fruits, vegetables, and soups. The rest needs to come from drinks, primarily water.
Check your hydration: Pale straw-coloured urine = well hydrated. Dark yellow or amber = drink more.