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Water Calculator
This calculator determines your recommended daily water intake based on your body weight and physical activity level. Enter your weight and average workout time per day to receive a personalized hydration target. The calculator accounts for baseline hydration needs and adjusts for fluid loss during exercise to provide an accurate daily water intake recommendation in liters.
Not sure what your numbers are? Do a test here.
This calculator provides an estimate and should not replace medical advice.
Your hydration is critically low. At this level, you may experience fatigue, headaches, dizziness, and difficulty concentrating. Dehydration can impair physical performance and cognitive function. Please increase your water intake immediately and consider setting hourly reminders to drink water throughout the day.
You're doing well! This is a solid baseline for daily hydration. At this level, you're meeting your body's essential water needs, supporting basic functions like circulation, digestion, and temperature regulation. Your body is getting enough water to maintain energy and focus throughout the day.
Excellent hydration! You're well above your target and supporting your body's needs effectively. At this level, you're promoting healthy kidney function, maintaining good skin elasticity, supporting muscle recovery, and ensuring efficient nutrient transport throughout your body.
Outstanding! You've achieved optimal hydration levels. This intake maximizes physical performance, cognitive function, and overall wellness. You're giving your body the best support for detoxification, joint lubrication, and cellular health. Keep up this excellent habit!
What does your result mean?
This is your estimated daily water target.
If you are:
In range
Keep your daily routine. Sip steadily across the day and include electrolytes around long workouts.
Below range
You're likely under-hydrated.
Add +0.4 to 0.8 L per hour of exercise, and aim for regular sips, for example 250 to 350 mL every 60 to 90 minutes.
Above range
Spread intake through the day. If you're drinking much more than the range without electrolytes, watch for low-sodium symptoms during long efforts.
Targets are guides, not medical advice. Adjust if you feel bloated, light-headed, or wake to urinate at night.
How is this calculated?
Evidence baseline
Starts from widely used adequate-intake guidance (~3.7 L per day men, 2.7 L per day women), with ~20% typically coming from food.
Sized to you
We normalize by body size at ~30 to 35 mL per kg per day (≈ 0.5 to 0.6 fl oz per lb).
Activity adjustment
Most adults lose ~0.5–1.5 L of sweat per hour in moderate–hard training. We add ~0.4–0.8 L per exercise hour as a practical replacement.
Add additional water if you are in extreme heat, using the sauna or if your medication or specific diet requires.
Environment & day-to-day
Hot/humid days, heavy clothing, illness, and some meds can push needs ~10–20% higher.
Why a range?
Sweat rate and intake vary. We show a personalized range instead of one "perfect" number.
Backed by leading scientific literature:
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