How to Calculate Hydration
What is Hydration?
Daily water intake recommendations vary by body weight, activity level, climate, and diet. The widely cited "8 glasses a day" is not evidence-based; individualised calculation is more accurate. About 20% of water intake comes from food.
Step-by-Step Guide
- 1Base requirement: approximately 33ml per kg body weight per day
- 2Activity: add 500ml for moderate activity, 1L for intense exercise
- 3Hot climate: add 500ml–1L
- 4Individual needs vary widely
Worked Examples
Input
70kg · moderate activity · temperate climate
Result
2.3L/day (~9 glasses)
70×33ml=2,310ml/day from drinks+food
Ready to calculate? Try the free Hydration Calculator
Try it yourself →