Water Intake Calculator
Estimate daily water needs based on body weight, activity, and climate. Outputs ounces, liters, cups, and glasses — these are guidelines, not strict rules.
Inputs
Pregnancy and breastfeeding raise fluid needs, and this estimate does not account for either — ask a midwife, doctor, or dietitian for a personal target. Same if you have a heart or kidney condition or take medication that affects fluid balance.
About Water Intake Calculator
How the estimate works
A common rule of thumb is roughly half to a full ounce per pound of body weight, plus extra for exercise. This calculator uses 0.6 oz/lb baseline plus 12 oz per 30 minutes of activity, scaled for climate.
Does food count?
About 20% of daily fluid comes from food — fruits, vegetables, soups. Coffee and tea count toward fluids despite mild diuretic effects; alcohol can be slightly dehydrating.
Metric or imperial?
Use the Units dropdown. Imperial takes your weight in pounds and reports fluid ounces; metric takes kilograms and reports millilitres and litres, with 250 mL glasses instead of 8-oz ones. Switching converts the weight already in the box, and the choice travels in your share link.
Pregnancy and breastfeeding
Both raise fluid needs, and this calculator does not add anything for them — the number you see is the general adult estimate. Treat it as a floor rather than a target and ask a midwife, doctor, or dietitian what is right for you.
Signs of adequate hydration
Pale yellow urine. Most adults pee 4-7 times daily. Dark yellow or amber means drink more. Crystal clear all the time means you may be overdoing it.