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 — If 18 6 Diet
Hydration target while following the if 18 6 diet.
OpenWater Intake — If 20 4 Diet
Hydration target while following the if 20 4 diet.
OpenWater Intake — Omad Diet
Hydration target while following the omad diet.
OpenWater Intake — 5 2 Diet
Hydration target while following the 5 2 diet.
OpenWater Intake — Adf Diet
Hydration target while following the adf diet.
OpenWater Intake — Warrior Diet
Hydration target while following the warrior diet.
OpenWater Intake — Vegan Diet
Hydration target while following the vegan diet.
OpenWater Intake — Raw Vegan Diet
Hydration target while following the raw vegan diet.
OpenWater Intake — Vegetarian Diet
Hydration target while following the vegetarian diet.
OpenWater Intake — Pescatarian Diet
Hydration target while following the pescatarian diet.
OpenWater Intake — Flexitarian Diet
Hydration target while following the flexitarian diet.
OpenWater Intake — Fruitarian Diet
Hydration target while following the fruitarian diet.
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.