Daily Water Intake Calculator
Estimate how much water to drink per day based on your body weight and activity level, free and instant right in your browser.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter your body weight in kilograms.
- Press Calculate for a daily water guide.
How it works
A common guide is about 33 mL of water per kilogram of body weight per day. Your needs rise with heat, exercise and some health conditions.
Worked example
70 kg. ≈ 70 × 33 mL = 2.31 L a day, about 9 cups.
Frequently asked questions
Does coffee or tea count?
Most fluids contribute, but water is best. Very high caffeine has a mild diuretic effect.
Is this a strict medical target?
No — it's a general guide. Needs vary with climate, activity, pregnancy and health conditions, so treat it as a starting point, not medical advice.
Should I drink more when exercising?
Yes — add roughly 500–700 mL per hour of exercise, and more in heat. Listen to thirst and check urine colour (pale straw is a good sign).
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Cite this tool
Zerdly. (2026). Daily Water Intake Calculator. Retrieved from https://www.zerdly.com/tools/daily-water-intake-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.