Water Intake Calculator
Your daily water target based on weight, activity, and climate
Your daily water target
Fluid ounces (US)
fl oz
Milliliters
ml
Liters
L
Cups (240 ml)
How to Use
- Enter your weight — Toggle between kilograms and pounds; the default follows the page language and your value converts automatically when you switch.
- Pick your activity level — Sedentary, moderate (~30 minutes of exercise per day), or active (60+ minutes per day).
- Pick your climate — Normal or hot. A hot climate adds an extra allowance for increased sweating.
- Read your target — Your daily water goal appears instantly in milliliters, liters, 240 ml cups, and US fluid ounces, with the most familiar unit highlighted.
Features
- Weight-based formula — The widely circulated 33 ml × kg guideline, adjusted for activity and climate.
- Activity and climate adjustments — +350 ml per 30 minutes of daily exercise, +750 ml for hot climates.
- All units at once — Milliliters, liters, 240 ml cups, and US fluid ounces shown simultaneously, with a locale-aware highlight (fl oz for English, ml for Chinese and German).
- kg / lb input — Locale-aware default weight unit with one-click toggle and automatic value conversion.
- 100% client-side privacy — Everything runs in your browser; nothing is sent anywhere.
Use Cases
- Daily hydration goal: Replacing the “8 glasses a day” myth with a number scaled to your body weight.
- Exercise planning: Seeing how a daily workout changes your water needs.
- Hot weather: Estimating the extra intake needed during summer or heat waves.
- Bottle math: Converting your target into bottle refills using the ml or fl oz readout.
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Frequently Asked Questions
How is my daily water target calculated?
The calculator starts with the widely used weight-based guideline of 33 ml of water per kilogram of body weight. It then adds 350 ml per 30 minutes of daily exercise (activity level) and 750 ml for a hot climate (the midpoint of the common 500–1000 ml adjustment). A sedentary 70 kg person in a normal climate gets about 2310 ml per day.
Is this medical advice?
No. This is a general guideline, not medical advice. Individual needs vary with health conditions, pregnancy, altitude, and diet, and both drinking too little and drinking too much can be harmful. If you have a medical condition (especially kidney or heart issues), follow your doctor's recommendation instead of any calculator.
Does coffee, tea, or water from food count toward the target?
This calculator intentionally counts plain water only and does not subtract water from food or other beverages. Estimating food water content accurately would require detailed dietary input, which is beyond the scope of this tool. In practice, food and drinks like tea or coffee do contribute to hydration, so treat the result as a simple, slightly conservative daily target.
Why is the result shown in ml, liters, cups, and fluid ounces?
All common units are shown at once so you can use whichever matches your bottle or glass. A cup is defined here as 240 ml, and a US fluid ounce is 29.5735 ml. The highlighted unit follows the page language: fluid ounces for English, milliliters for Chinese and German.
What does the activity level add?
Each activity step represents roughly 30 minutes of daily exercise and adds 350 ml: sedentary adds 0 ml, moderate (~30 min/day) adds 350 ml, and active (60+ min/day) adds 700 ml. This approximates typical sweat losses for moderate exercise; intense training or endurance sports may require more.