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
How Many 20 oz Bottles Per Day?
Number of 20 oz bottles you need daily to hit your hydration target.
OpenHow Many 24 oz Bottles Per Day?
Number of 24 oz bottles you need daily to hit your hydration target.
OpenHow Many 32 oz Bottles Per Day?
Number of 32 oz bottles you need daily to hit your hydration target.
OpenHow Many 40 oz Bottles Per Day?
Number of 40 oz bottles you need daily to hit your hydration target.
OpenHow Many 48 oz Bottles Per Day?
Number of 48 oz bottles you need daily to hit your hydration target.
OpenHow Many 64 oz Bottles Per Day?
Number of 64 oz bottles you need daily to hit your hydration target.
OpenHow Many 80 oz Bottles Per Day?
Number of 80 oz bottles you need daily to hit your hydration target.
OpenHow Many 100 oz Bottles Per Day?
Number of 100 oz bottles you need daily to hit your hydration target.
OpenHow Many 128 oz Bottles Per Day?
Number of 128 oz bottles you need daily to hit your hydration target.
OpenHow Many 500 ml Bottles Per Day?
Number of 500 ml bottles you need daily to hit your hydration target.
OpenHow Many 750 ml Bottles Per Day?
Number of 750 ml bottles you need daily to hit your hydration target.
OpenHow Many 1000 ml Bottles Per Day?
Number of 1000 ml bottles you need daily to hit your hydration target.
OpenSimple, accurate, personalized
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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.