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 — Waiter Server
Job-specific hydration for waiter server — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Housekeeper Hotel
Job-specific hydration for housekeeper hotel — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Landscaper
Job-specific hydration for landscaper — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Roofer Summer
Job-specific hydration for roofer summer — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Electrician Field
Job-specific hydration for electrician field — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Plumber Field
Job-specific hydration for plumber field — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Mechanic Shop
Job-specific hydration for mechanic shop — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Police Patrol
Job-specific hydration for police patrol — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Firefighter Shift
Job-specific hydration for firefighter shift — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Paramedic Shift
Job-specific hydration for paramedic shift — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Military Field
Job-specific hydration for military field — shift length, heat exposure, and workload adjustments.
OpenWater Intake — Farmer Field
Job-specific hydration for farmer field — shift length, heat exposure, and workload adjustments.
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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.