Base formula

Base = body weight × 0.033 litres/kg. Then we add for activity (+0 to +1.05L) and climate (+0 to +0.75L). A 70 kg person in moderate climate with moderate activity needs approximately 3.0–3.3 litres per day.

Waking hours are assumed to be 16 hours for the "ml per hour" metric. Space your intake evenly throughout the day.