The water intake works like this: it estimates daily water intake from body weight, then adjusts for exercise and hot climate using widely-cited activity multipliers. Everything happens on your device - the input never leaves your tab unless the tool clearly states it performs a server-side lookup.
How to use the Water Intake
Enter the values the calculator asks for.
Double-check the unit or period next to each field (per month vs per year, cm vs m).
Read the result together with the breakdown shown beneath it.
Adjust one input at a time to compare scenarios side by side.
Features
Calculate daily water intake needs for hydration
Instant result, no page reload
Works in any modern browser, desktop or mobile
Free with no signup
Common mistakes to avoid
Mixing units or periods between fields
Rounding inputs before the final calculation
Treating estimates as guarantees for major decisions
Examples
Input
Result
70 kg · 45 min exercise · hot climate
Target ~3.3 litres including ~0.5L extra for activity and heat
Best used for
Getting a reliable answer for water intake without installing an app
One-off tasks done in under a minute from any device
Checking results before committing them to something important
Working on a phone where desktop software is unavailable
Privacy
Calculations run in your browser. Enter only what the calculation needs.
Frequently asked questions
Does coffee count?
Yes - the diuretic effect of moderate caffeine is smaller than the fluid it delivers. All beverages and water-rich food contribute.
How much extra water does exercise add?
The common multiplier adds roughly 350-500 ml per 30 minutes of activity, and hot climates add a similar increment on top - the tool totals weight-based base plus both adjustments.
Does coffee or tea count toward the total?
Yes in practice - caffeinated drinks are mostly water and the diuretic effect is small at habitual intakes, though plain water is what the baseline number assumes.