Calculators
Free hydration calculators.
Work out how much water you need — for a normal day, a hard workout, a heatwave, or a night out. Evidence-based, no sign-up, results in seconds.
Daily intake
Daily water intake
How much water should you drink a day? Get a personalized daily water intake from your weight, activity, climate and more — in liters, ounces, glasses and bottles.
Open calculator →Water intake by weight
Calculate how much water to drink based on your body weight. A simple ml-per-kg (or oz-per-pound) estimate with an activity adjustment and a printable target.
Open calculator →Water for weight loss
How much water should you drink to lose weight? An honest calculator: your daily target, pre-meal water timing, and the calories you save by swapping sugary drinks.
Open calculator →Water intake for kids
How much water should a child drink? Age-based daily water targets for toddlers, kids and teens from EFSA reference values, with hot-day and sports-day adjustments.
Open calculator →Exercise & heat
Sweat rate
Measure your sweat rate from pre- and post-workout weight and the fluid you drank. Get liters per hour, percent body weight lost, and a drinking plan for next time.
Open calculator →Exercise hydration
How much water to drink before, during and after a workout. Enter duration, intensity and conditions to get a simple before/during/after hydration plan.
Open calculator →Hot weather hydration
How much extra water do you need in the heat? Enter temperature, humidity and time outdoors to get your heat index and an adjusted daily fluid target.
Open calculator →Electrolyte replacement
Estimate the sodium you lose in sweat during long workouts and how much to replace. Built for endurance sessions over 90 minutes, not everyday hydration.
Open calculator →Everyday tools
Caffeine & alcohol offset
Does coffee dehydrate you? How much water should you drink after alcohol? Enter your coffees, teas and drinks to see their real hydration effect and the extra water to add.
Open calculator →Water unit converter
Convert water between milliliters, liters, fluid ounces, cups, glasses and bottles. Find out how many bottles make 2 liters or how many ounces are in a glass.
Open calculator →Dehydration check
A quick, non-medical dehydration check based on thirst, urine color, symptoms and today's intake. Get a rough hydration status and a catch-up plan for the next few hours.
Open calculator →Hydration schedule
Turn your daily water goal into a drinking schedule. Enter wake and bed times to get a timetable of when to drink and how much, tapered before bed.
Open calculator →Pet water intake
How much water should a dog or cat drink per day? Estimate your pet's daily water needs from weight, diet (dry vs wet food), activity and weather.
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