Hydration Goal Calculator
Calculate your personal daily hydration goal based on body weight, exercise duration and climate. Skip the lazy 8-glasses rule.
Your daily hydration goal depends on three things: body weight, how much you exercise and the climate you live in. The "8 glasses a day" rule treats a 50 kg desk worker in a cool office and a 90 kg construction worker in 35°C heat as identical, which they obviously aren't.
The Formula
A practical baseline used in sports nutrition: 33 ml per kg of body weight for sedentary baseline, plus 500-1,000 ml per hour of exercise, with adjustments for climate.
Personalized Examples
| Profile | Daily target |
|---|---|
| 60 kg sedentary, cool climate | ~1.8 L |
| 70 kg office worker, 30 min gym, moderate | ~2.5 L |
| 75 kg construction worker, mild weather | ~3.5 L |
| 70 kg runner, 90-min run at 30°C | ~5.0 L+ |
| 80 kg marathoner, race day hot | ~6-8 L |
Better Markers Than Volume
Color of your urine is the easiest real-time hydration check:
- Pale yellow (color of lemonade): adequately hydrated
- Dark amber: drink more
- Clear and copious: probably overdoing it (rare problem outside endurance events)
Use the Full Calculator
The Water Intake Calculator handles every scenario described on this page. For the deeper math and worked examples, read the companion guide.