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 at Age 42
Daily hydration target for a 42-year-old adult.
OpenWater Intake at Age 43
Daily hydration target for a 43-year-old adult.
OpenWater Intake at Age 44
Daily hydration target for a 44-year-old adult.
OpenWater Intake at Age 45
Daily hydration target for a 45-year-old adult.
OpenWater Intake at Age 46
Daily hydration target for a 46-year-old adult.
OpenWater Intake at Age 47
Daily hydration target for a 47-year-old adult.
OpenWater Intake at Age 48
Daily hydration target for a 48-year-old adult.
OpenWater Intake at Age 49
Daily hydration target for a 49-year-old adult.
OpenWater Intake at Age 50
Daily hydration target for a 50-year-old adult.
OpenWater Intake at Age 51
Daily hydration target for a 51-year-old adult.
OpenWater Intake at Age 52
Daily hydration target for a 52-year-old adult.
OpenWater Intake at Age 53
Daily hydration target for a 53-year-old adult.
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Choose the one that matches your situation from the grid above.
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Weight, activity, climate, species — takes under 30 seconds.
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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.