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
Water Intake at 4000 m Altitude
Daily hydration target at 4000 m elevation.
OpenWater Intake at 4500 m Altitude
Daily hydration target at 4500 m elevation.
OpenWater Intake at 5000 m Altitude
Daily hydration target at 5000 m elevation.
OpenWater Intake at 5500 m Altitude
Daily hydration target at 5500 m elevation.
OpenWater Intake at 6000 m Altitude
Daily hydration target at 6000 m elevation.
OpenWater Intake at 7000 m Altitude
Daily hydration target at 7000 m elevation.
OpenWater Intake at 8000 m Altitude
Daily hydration target at 8000 m elevation.
OpenWater Intake at 8848 m Altitude
Daily hydration target at 8848 m elevation.
OpenWater Intake at 8% Body Fat
Hydration target for 8% body fat based on lean mass.
OpenWater Intake at 10% Body Fat
Hydration target for 10% body fat based on lean mass.
OpenWater Intake at 12% Body Fat
Hydration target for 12% body fat based on lean mass.
OpenWater Intake at 14% Body Fat
Hydration target for 14% body fat based on lean mass.
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.