Daily Water Intake Calculator
From weight, activity and climate, estimate daily water goal (litres).
Input Data
Results
At a glance:Base water = weight (kg) × 35 mL (general adult baseline). Total = base + activity extra + hot-climate extra. This is the 'drink additional' pure water, not including water from food.
Formula
base (mL) = weight × 35.
total (mL) = base + activity + hot extra.
litres = total ÷ 1000.
How to Use
- Enter weight.
- Add activity extra (e.g. 30 min sweat ≈ 300–500 mL).
- Add hot/humid extra.
- The tool gives base and total daily water.
Case Studies
65 kg, activity 500, hot 0
base = 65 × 35 = 2,275 mL.
total = 2,275 + 500 = 2,775 mL.
≈ 2.78 L.
FAQ
Why 35 mL/kg?
A common simple baseline (range ~30–35 mL/kg) for general adults. Those with kidney disease, heart failure or fluid restriction should follow medical advice, not this formula.
Does food water count?
This tool counts only 'additional' pure water. Fruits, vegetables and soup supply ~20% of daily water, so you can drink a bit less than the total. Use thirst and urine colour (pale yellow) as guides.
How much after exercise?
Roughly 300–500 mL per 30 min of moderate exercise; high-intensity or long sessions can exceed 750 mL. The activity field is for this.
Can too much water be harmful?
Very large amounts in a short time can dilute blood sodium (water intoxication). Spread intake across the day; if fluid-restricted (kidney/heart), follow medical instructions.
Do tea and coffee count?
Moderate caffeine drinks still count as fluid (limited diuretic effect); alcohol is diuretic and does not count. Plain water and light tea are safest.
Children or elderly?
Children have higher metabolism but lower weight; follow age-specific guidance. Elderly have dulled thirst and dehydrate easily; drink on a schedule. This tool uses adult 35 mL/kg, not for infants.
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.