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Daily water intake calculator
Estimate how much water to drink each day based on your body weight and activity level.
Enter your details above to see your result.
How it works
We estimate fluid needs from body weight at roughly 30–40 mL per kilogram, scaling up with activity. This is total fluid (food and other drinks contribute too), and needs rise further in heat, illness, pregnancy, or hard training. Let thirst and urine colour guide you.
| Activity | Per kg |
|---|---|
| Sedentary | 30 mL |
| Active | 35 mL |
| Very active / athlete | 40 mL |
How it's calculated
We estimate daily fluid needs from your body weight using a common guideline of roughly 30–40 mL per kilogram, scaled by activity (about 30 mL/kg when sedentary, up to 40 mL/kg for athletes). Individual needs vary with climate, health, and diet.
How to use this calculator
- Enter your details — such as age, weight, and height — in the fields above.
- Choose any options that apply, like your activity level, goal, or formula.
- Read your result instantly. It updates as you type — no sign-up required.
Sources: Based on the widely used ~30–40 mL/kg body-weight fluid guideline; see EFSA and Institute of Medicine dietary reference values for water.
These calculators give general estimates for healthy adults and are not medical or dietary advice. For individual guidance, consult a registered dietitian or your healthcare provider.
Reviewed by the NutraPlanner nutrition team. · Last updated 2026-06-17
Frequently asked questions
How much water should I drink a day?
A common estimate is about 30–40 mL per kilogram of body weight, scaling up with activity. For many adults that's roughly 2–3 litres of total fluid per day, including water from food and other drinks.
Does food and coffee count?
Yes — total fluid includes water in food and most beverages. Moderate coffee and tea count toward your intake despite their mild diuretic effect.
When do I need more?
Needs rise with heat, exercise, illness (fever, vomiting, diarrhoea), pregnancy, and breastfeeding. Use thirst and pale-yellow urine as practical guides.
Plan meals around these numbers
NutraPlanner turns targets like these into branded meal plans for your clients — or yourself.