Human Calculators
Daily water intake calculators for adults — men, women, elderly, weight-based, and weather-based.
Most popular in Human Calculators
Adult Daily Water Intake
Personalized daily water target for healthy adults, adjusted for weight, activity, and climate.
Open calculatorElderly Water Intake (65+)
Daily hydration target for older adults, with a safe minimum floor and climate adjustments.
Open calculatorWater Intake for Weight Loss
Higher-end daily target with pre-meal water boost that supports satiety and weight loss.
Open calculatorExplore the full library
How Many 1250 ml Bottles Per Day?
Number of 1250 ml bottles you need daily to hit your hydration target.
OpenHow Many 1500 ml Bottles Per Day?
Number of 1500 ml bottles you need daily to hit your hydration target.
OpenHow Many 2000 ml Bottles Per Day?
Number of 2000 ml bottles you need daily to hit your hydration target.
OpenHow Many 2500 ml Bottles Per Day?
Number of 2500 ml bottles you need daily to hit your hydration target.
OpenHow Many 3000 ml Bottles Per Day?
Number of 3000 ml bottles you need daily to hit your hydration target.
OpenWater Intake at 500 m Altitude
Daily hydration target at 500 m elevation.
OpenWater Intake at 1000 m Altitude
Daily hydration target at 1000 m elevation.
OpenWater Intake at 1500 m Altitude
Daily hydration target at 1500 m elevation.
OpenWater Intake at 2000 m Altitude
Daily hydration target at 2000 m elevation.
OpenWater Intake at 2500 m Altitude
Daily hydration target at 2500 m elevation.
OpenWater Intake at 3000 m Altitude
Daily hydration target at 3000 m elevation.
OpenWater Intake at 3500 m Altitude
Daily hydration target at 3500 m elevation.
OpenSimple, accurate, personalized
Pick your calculator
Choose the one that matches your situation from the grid above.
Enter a few details
Weight, activity, climate, species — takes under 30 seconds.
Get your target
A research-backed daily target plus an hourly schedule.
Learn the science behind human calculators
Read our in-depth guides for research-backed context on every calculator here.