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 — Spain
Localized daily hydration target for spain residents with climate factored in.
OpenWater Intake — Italy
Localized daily hydration target for italy residents with climate factored in.
OpenWater Intake — Netherlands
Localized daily hydration target for netherlands residents with climate factored in.
OpenWater Intake — Sweden
Localized daily hydration target for sweden residents with climate factored in.
OpenWater Intake — Norway
Localized daily hydration target for norway residents with climate factored in.
OpenWater Intake — Turkey
Localized daily hydration target for turkey residents with climate factored in.
OpenWater Intake — Iran
Localized daily hydration target for iran residents with climate factored in.
OpenWater Intake — Iraq
Localized daily hydration target for iraq residents with climate factored in.
OpenWater Intake — Morocco
Localized daily hydration target for morocco residents with climate factored in.
OpenWater Intake — Ethiopia
Localized daily hydration target for ethiopia residents with climate factored in.
OpenWater Intake — Chile
Localized daily hydration target for chile residents with climate factored in.
OpenWater Intake — Nurse Shift
Job-specific hydration for nurse shift — shift length, heat exposure, and workload adjustments.
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.