Hiking Water Needs Calculator
Estimate how much water to carry per day on a hike from duration, intensity and temperature.
How it works
water = hours × base rate (L/hr by effort) × temperature multiplier
A widely used rule of thumb is about half a liter of water per hour of moderate hiking, adjusted up for heat and hard climbing and down in cool weather. This estimate scales that base rate by effort and temperature so a strenuous hike on a hot day comes out near a liter per hour. Treat it as a starting plan: monitor thirst and urine color, and always carry a margin plus a way to treat water on longer routes.
Worked example
Six hours of moderate hiking (0.5 L/hr) on a mild day (×1.0) needs 6 × 0.5 = 3.0 L, about 101 oz. On a hot day (×1.3) that rises to about 3.9 L.
Frequently asked questions
Is half a liter per hour enough?
It is a reasonable average for moderate effort in mild weather. Heat, altitude, heavy loads and steep climbs can push consumption to a liter per hour or more, so scale up and carry a reserve.
Should I carry all the water I need?
On short day hikes, yes. On longer trips, carry enough to reach the next reliable source plus a buffer, and bring a filter or purification method rather than the full trip volume.
Does this account for cooking or camp water?
No — it covers drinking water while moving. Add roughly 1–2 L per person per day for cooking and cleanup if you are camping.
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This calculator is for educational purposes. Double-check important results before acting on them.