Your Details
kg
years
Your Daily Water Target
0
ml / day
= 0 glasses (250ml) · 0 liters
Hourly Hydration Schedule
Spread your intake throughout the day — your kidneys can only process ~1 liter per hour:
Hydration Status Signs
Urine Color Guide
💧 Well hydrated⚠️ Drink more🚨 Severely dehydrated
How Much Water Do You Actually Need?
Also searched as: water intake calculator free | how much water should i drink | daily water intake calculator | hydration calculator Optimized for US users with American units and terminology.
The popular "8 glasses a day" rule is an oversimplification. Water needs vary significantly based on body size, activity level, climate, and health status. A general starting point is 30–35ml per kg of body weight, adjusted upward for exercise (add 500–1000ml per hour of intense activity), hot weather, and special conditions like pregnancy.
Water vs Total Fluid Intake
About 20% of your water intake comes from food — fruits, vegetables, and soups all contribute. Coffee and tea also count toward hydration despite being mild diuretics. The net diuretic effect of moderate caffeine intake is small. Focus on total fluid intake rather than just plain water.
Use the Water Intake Calculator above — enter your values and get instant results. This free online tool calculates how much water should i drink a day without any download or signup required. Results update in real time as you type.
Use the Water Intake Calculator above — enter your values and get instant results. This free online tool calculates water intake calculator by weight without any download or signup required. Results update in real time as you type.
Yes — overhydration (hyponatremia) can be dangerous, though it's rare in everyday life. It's most commonly seen in endurance athletes drinking excessive plain water without electrolytes. Your kidneys can process about 1 liter per hour maximum. Drinking to thirst is a reliable guideline for most healthy adults.
Yes. While caffeine has a mild diuretic effect, research shows that moderate coffee consumption (3–4 cups/day) contributes net positive hydration. Tea, juice, and milk also count. Only alcohol has a significant dehydrating effect that reduces net fluid retention.
A practical guideline: drink 500ml (17oz) 2 hours before exercise, 200–300ml every 15–20 minutes during exercise, and 500–750ml for every 0.5kg of body weight lost during exercise. Sweat rates vary widely — some people lose up to 2.5 liters per hour in hot conditions.