Daily Water Intake Calculator
Estimate how much water to drink each day from your weight and activity, shown in litres and cups β in your browser.
π Runs entirely in your browser. Your input and output are never sent to a server or stored β fully private.
Estimate how much water to drink per day from your weight and exercise.
A common guideline (~35 ml per kg) plus ~350 ml for every 30 min of exercise. Needs vary with climate, health and diet.
Estimates only β not medical advice.
About this tool
Not sure how much to drink each day? Enter your body weight and how long you exercise, and this calculator estimates a daily water target, shown in litres, millilitres, cups and fluid ounces. It uses a simple per-kilogram guideline and adds extra for time spent sweating, giving a sensible baseline you can adjust to taste. It is handy for anyone trying to stay better hydrated. The numbers are worked out in your browser, so nothing you enter is uploaded anywhere.
Frequently asked questions
How is the target calculated?
The estimate uses about 35 millilitres of water per kilogram of body weight, then adds roughly 350 millilitres for every 30 minutes of exercise to cover sweat losses. So a 70 kg person who works out for half an hour gets about 70 Γ 35 + 350, which is around 2.8 litres. That total includes water from all drinks, not just plain water.
Do food and other drinks count?
Yes. Roughly a fifth of most people's water comes from food, especially fruit, vegetables and soups, and tea, coffee and milk all count toward the total despite the myth that coffee dehydrates you. Because of this, the figure here is a target for total fluid, so you rarely need to drink the whole amount as plain water.
Can I just follow this number every day?
It is a general guideline, not a medical prescription. Real needs shift with heat, humidity, altitude, illness, pregnancy and certain medications, and some heart or kidney conditions require limiting fluids, so check with a doctor if that applies to you. A good everyday cue is pale-yellow urine. The calculation happens entirely in your browser and nothing you enter is stored.