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.
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Senior Water Intake at Age 98
Age-adjusted daily hydration target for a 98-year-old senior.
OpenSenior Water Intake at Age 99
Age-adjusted daily hydration target for a 99-year-old senior.
OpenSenior Water Intake at Age 100
Age-adjusted daily hydration target for a 100-year-old senior.
OpenWater Intake for 40 kg
Precise daily target for a 40 kg adult.
OpenWater Intake for 41 kg
Precise daily target for a 41 kg adult.
OpenWater Intake for 42 kg
Precise daily target for a 42 kg adult.
OpenWater Intake for 43 kg
Precise daily target for a 43 kg adult.
OpenWater Intake for 44 kg
Precise daily target for a 44 kg adult.
OpenWater Intake for 90 lb
Precise daily target for a 90 lb adult.
OpenWater Intake for 91 lb
Precise daily target for a 91 lb adult.
OpenWater Intake for 92 lb
Precise daily target for a 92 lb adult.
OpenWater Intake for 93 lb
Precise daily target for a 93 lb adult.
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.