This water intake calculator estimates a daily hydration target from your body weight, with adjustments for activity and climate.
Health
Water Intake Calculator
Estimate daily water intake needs by age, sex and life stage.
Calculator
About this calculator
Formula notes
A common rule: 30–35 mL per kg of body weight per day; add roughly 350–500 mL per 30 min of exercise.
Worked examples
- Example: at 70 kg, baseline intake is about 2.1–2.45 L per day before exercise adjustments.
- A 70 kg adult using a planning factor of 30 mL/kg gets 2.1 L/day before accounting for food moisture, climate, exercise, pregnancy, or medical restrictions.
How to use it
- Enter your body weight.
- Add activity level or climate if the tool asks.
- Read the suggested daily water target.
Frequently asked questions
Does coffee count toward intake?
Yes. Despite mild caffeine effects, coffee and tea contribute net hydration.
Can I drink too much water?
Yes. Very rapid excessive intake can dilute blood sodium (hyponatremia); spread intake across the day.
Limits and interpretation
- General formulas cannot account for all water from food and beverages or for losses caused by heat, altitude, exercise, fever, vomiting, or diarrhoea.
- Kidney, heart, liver, and endocrine conditions can require individualized fluid advice; excessive intake can also be harmful.