Water Intake Calculator
Estimate your daily water needs based on body weight, exercise duration, and climate.
Overview
A common clinical heuristic sets baseline fluid need at about 35 millilitres per kilogram of body weight per day, with roughly 500 additional millilitres for each half hour of exercise. A 70 kg adult therefore starts near 2.45 litres, adjusted upward for training volume, heat and altitude.
Daily Water Intake
mL
Liters
L
Cups (237 mL)
Daily Glasses (250 mL)
Breakdown
| Source | Amount |
|---|---|
| Base (weight x 35 mL) | mL |
| Exercise adjustment | + mL |
| Climate adjustment | mL |
This is a general estimate. Actual water needs vary based on individual health conditions, diet, medications, and other factors. Consult a healthcare professional for personalized hydration advice.
How to Use
-
1
Enter your values
Type your numbers into the Water Intake Calculator input fields.
-
2
Adjust the options
Choose the units, method, or region that fits your situation, or apply a quick preset.
-
3
Read the result instantly
The result updates as you type — no submit button, and nothing is sent to a server.
About
Total intake includes water contained in food, which supplies roughly a fifth of the daily requirement in most diets, and the water content of tea, coffee and other beverages. The frequently repeated eight-glasses figure has no identified source in the physiological literature and is not the basis for the per-kilogram heuristic.
Thirst regulates intake accurately in healthy adults under ordinary conditions, so calculated targets matter most where thirst is a poor guide: during prolonged endurance exercise, in older adults whose thirst response is blunted, and in hot environments. Overconsumption is not harmless — exercise-associated hyponatraemia arises from drinking well beyond sweat losses.