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 — Qatar
Localized daily hydration target for qatar residents with climate factored in.
OpenWater Intake — Egypt
Localized daily hydration target for egypt residents with climate factored in.
OpenWater Intake — Nigeria
Localized daily hydration target for nigeria residents with climate factored in.
OpenWater Intake — Kenya
Localized daily hydration target for kenya residents with climate factored in.
OpenWater Intake — South Africa
Localized daily hydration target for south africa residents with climate factored in.
OpenWater Intake — China
Localized daily hydration target for china residents with climate factored in.
OpenWater Intake — Japan
Localized daily hydration target for japan residents with climate factored in.
OpenWater Intake — South Korea
Localized daily hydration target for south korea residents with climate factored in.
OpenWater Intake — Vietnam
Localized daily hydration target for vietnam residents with climate factored in.
OpenWater Intake — Thailand
Localized daily hydration target for thailand residents with climate factored in.
OpenWater Intake — Philippines
Localized daily hydration target for philippines residents with climate factored in.
OpenWater Intake — Indonesia
Localized daily hydration target for indonesia residents with climate factored in.
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.