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 15% Body Fat
Hydration target for 15% body fat based on lean mass.
OpenWater Intake at 16% Body Fat
Hydration target for 16% body fat based on lean mass.
OpenWater Intake at 18% Body Fat
Hydration target for 18% body fat based on lean mass.
OpenWater Intake at 20% Body Fat
Hydration target for 20% body fat based on lean mass.
OpenWater Intake at 22% Body Fat
Hydration target for 22% body fat based on lean mass.
OpenWater Intake at 25% Body Fat
Hydration target for 25% body fat based on lean mass.
OpenWater Intake at 28% Body Fat
Hydration target for 28% body fat based on lean mass.
OpenWater Intake at 30% Body Fat
Hydration target for 30% body fat based on lean mass.
OpenWater Intake at 32% Body Fat
Hydration target for 32% body fat based on lean mass.
OpenWater Intake at 35% Body Fat
Hydration target for 35% body fat based on lean mass.
OpenWater Intake at 38% Body Fat
Hydration target for 38% body fat based on lean mass.
OpenWater Intake at 40% Body Fat
Hydration target for 40% 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.