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 Age 15
Daily water for a healthy 15-year-old.
OpenWater Intake at Age 16
Daily water for a healthy 16-year-old.
OpenWater Intake at Age 17
Daily water for a healthy 17-year-old.
OpenWater Intake at Age 18
Daily water for a healthy 18-year-old.
OpenWater Intake at Age 19
Daily water for a healthy 19-year-old.
OpenWater Intake at Age 20
Daily water for a healthy 20-year-old.
OpenWater Intake at Age 21
Daily water for a healthy 21-year-old.
OpenWater Intake at Age 22
Daily water for a healthy 22-year-old.
OpenWater Intake at Age 23
Daily water for a healthy 23-year-old.
OpenWater Intake at Age 24
Daily water for a healthy 24-year-old.
OpenWater Intake at Age 25
Daily water for a healthy 25-year-old.
OpenWater Intake at Age 26
Daily water for a healthy 26-year-old.
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.