Free tool , health
How much water do you actually need?
The famous eight glasses rule was never science. A better starting point scales with your body, your activity, and your day, and it counts the water in food and other drinks too. Everything runs in your browser, nothing is saved or sent anywhere.
Starting point: about half an ounce per pound of body weight, adjusted for exercise and heat. Roughly 20 percent of daily fluid typically comes from food, and coffee and tea count toward the total despite the old myth.
The honest version of hydration advice
Thirst is a good sensor for most healthy adults, and pale-yellow urine is the classic sanity check. The number above is a target to sanity-check your day against, not a quota to force down. Needs genuinely go up with exercise, heat, illness, pregnancy, and breastfeeding, and older adults often feel thirst less reliably and benefit from drinking on a schedule.
General information, not medical advice. Some conditions, including kidney and heart conditions, require medically-set fluid limits. It is also possible to drink dangerously too much, endurance athletes should follow event-specific guidance.
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