Water Intake Calculator

A common starting point for healthy adults is about 35 mL of water per kilogram of body weight, then adding more for exercise and hot or dry climates. For a 70 kg person at rest in a temperate climate that's roughly 2.4 litres. This calculator applies that estimate and adds about 12 mL per minute of exercise plus a climate allowance. It's a general guide, not a medical prescription.

Yes. The figure here is total fluid for the day, and food (especially fruit, vegetables, and soup) plus other drinks such as tea, milk, and coffee all contribute. Many people get roughly a fifth of their fluid from food. So you usually don't need to drink the whole amount as plain water.

It adds about 12 millilitres of water per minute of exercise (around 350 mL for a 30-minute session) to replace what you lose through sweat, applies a small activity multiplier to the weight-based base, and adds a fixed allowance for warm (350 mL) or hot and dry (700 mL) conditions. These are rounded rules of thumb, so treat the result as an estimate.

No. Everything runs in your browser. The weight, activity, and climate you enter are used only to calculate on this page and aren't uploaded or saved. The optional reminder beeps only while this tab stays open and stops the moment you close it or press stop.