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 27
Daily water for a healthy 27-year-old.
OpenWater Intake at Age 28
Daily water for a healthy 28-year-old.
OpenWater Intake at Age 29
Daily water for a healthy 29-year-old.
OpenWater Intake at Age 30
Daily water for a healthy 30-year-old.
OpenWater Intake at Age 31
Daily water for a healthy 31-year-old.
OpenWater Intake at Age 32
Daily water for a healthy 32-year-old.
OpenWater Intake at Age 33
Daily water for a healthy 33-year-old.
OpenWater Intake at Age 34
Daily water for a healthy 34-year-old.
OpenWater Intake at Age 35
Daily water for a healthy 35-year-old.
OpenWater Intake at Age 36
Daily water for a healthy 36-year-old.
OpenWater Intake at Age 37
Daily water for a healthy 37-year-old.
OpenWater Intake at Age 38
Daily water for a healthy 38-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.