Every tool below is free, works instantly in your browser, and never sends your data anywhere. Pick the one that fits — or start with our flagship water intake calculator.
Water Intake Calculator
Our flagship tool: your personal daily target from weight, activity level, and climate — with a full breakdown.
Daily Water Intake by Weight
A quick baseline from your body weight using the 35 ml per kg rule of thumb.
Water Intake for Exercise
Workout-day targets that add estimated sweat loss to your daily baseline.
Hydration Reminder Timer
Gentle reminders at your chosen interval, plus a glass tracker for today.
Caffeine Intake Calculator
Total your daily caffeine from coffee, tea, and energy drinks against the 400 mg benchmark.
Kids Water Intake Calculator
Age-based daily targets for children, from toddlers to teens.
Water Intake in Summer Heat
Hot-day targets adjusted for temperature and hours spent outdoors.
Want to understand the science?
Head to our guides page for plain-language explainers on electrolytes, kids’ hydration, and more.
For information only — not medical advice.