How to Calculate Daily Water Intake
What is Daily Water Intake?
Daily water intake requirements depend on body weight, activity level, climate, and diet. The old "8 glasses a day" (2 litres) rule lacks scientific basis. The European Food Safety Authority recommends 2.5L/day for men and 2.0L/day for women, including water from food (which contributes ~20%).
Step-by-Step Guide
- 1General baseline: 35ml per kg of body weight per day
- 2Add 500–750ml for each hour of exercise
- 3Add 500ml in hot weather or high humidity
- 4Caffeinated drinks count towards intake despite mild diuretic effect
- 5Clear to pale yellow urine indicates good hydration
Worked Examples
Frequently Asked Questions
What is Water Intake?
Daily water intake requirements depend on body weight, activity level, climate, and diet. The old "8 glasses a day" (2 litres) rule lacks scientific basis
How accurate is the Water Intake calculator?
The calculator uses the standard published formula for water intake. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.
What units does the Water Intake calculator use?
This calculator works with kilograms, inches, litres, percentages. You can enter values in the units shown — the calculator handles all conversions internally.
What formula does the Water Intake calculator use?
The calculator applies the standard formula for this type of calculation. See the 'How It Works' steps above for the detailed formula breakdown.
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