Water intake calculator — daily hydration range
Estimate a practical daily drinking range from weight, exercise and heat, with glasses, hourly pace and transparent adjustments.
Estimate a daily drinking range
Use a practical range instead of a falsely exact target. Weight, exercise and hot conditions adjust the starting estimate.
A planning estimate for healthy adults, not a medical prescription.
How the estimate works
The transparent heuristic uses 30 ml/kg, 350 ml per 30 minutes of exercise and 10% of the base in hot conditions. The result shows a ±10% range.
Drinks are not total water
Water also comes from other beverages and foods. Do not confuse this practical drinking range with an official total-water reference.
When needs change
Heat, prolonged activity, fever, vomiting and diarrhea can change needs substantially. Electrolytes may matter during hours of sweating.
Important limits
Do not use with kidney or heart disease, fluid restriction, pregnancy, breastfeeding or acute illness; clinical advice takes priority.
Privacy
All values are calculated locally in the browser and are not sent.
Official guidance
Frequently asked questions
Do coffee and tea count?
Beverages and water-rich foods contribute to total intake. Sugar, alcohol and high caffeine intake need separate consideration.
Does everyone need exactly two litres?
No. Body size, diet, activity, climate and health differ. Use the range as a starting point and follow thirst and clinical advice.
Plan energy and nutrition with the calorie calculator.
