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 39
Daily water for a healthy 39-year-old.
OpenWater Intake at Age 40
Daily water for a healthy 40-year-old.
OpenWater Intake at Age 41
Daily water for a healthy 41-year-old.
OpenWater Intake for 45 kg
Precise daily target for a 45 kg adult.
OpenWater Intake for 46 kg
Precise daily target for a 46 kg adult.
OpenWater Intake for 47 kg
Precise daily target for a 47 kg adult.
OpenWater Intake for 48 kg
Precise daily target for a 48 kg adult.
OpenWater Intake for 49 kg
Precise daily target for a 49 kg adult.
OpenWater Intake for 50 kg
Precise daily target for a 50 kg adult.
OpenWater Intake for 51 kg
Precise daily target for a 51 kg adult.
OpenWater Intake for 52 kg
Precise daily target for a 52 kg adult.
OpenWater Intake for 53 kg
Precise daily target for a 53 kg adult.
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.