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
ADHD Focus Water Intake
Focus-support hydration.
OpenAcne Hydration Plan
Skin-clarity water schedule.
OpenEczema Water Intake
Skin-barrier hydration.
OpenPsoriasis Water Intake
Skin-condition hydration.
OpenRosacea Water Intake
Flush-reduction hydration.
OpenDry Skin Water Target
Skin-hydration plan.
OpenHair Growth Water Intake
Follicle-supportive hydration.
OpenNail Strength Water Intake
Nail-supportive hydration.
OpenDry Eye Water Intake
Ocular-surface hydration.
OpenBad Breath Hydration Plan
Halitosis-reduction plan.
OpenDry Mouth (Xerostomia) Water
Xerostomia hydration.
OpenSjögren's Syndrome Water
Sjögren's hydration plan.
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.