Water Intake Calculator
Find out how much water you should be drinking each day based on your body weight and activity level.
Under 24C / 75F
Capped. Beyond about 6 litres a day your kidneys cannot keep up, and drinking more is not safer. If you genuinely sweat this much, replace salt as well as water.
| Reason | Amount |
|---|---|
| Your body size | 94 oz |
| Exercise | 10 oz |
What actually changes how much you need
The eight-glasses rule is a slogan, not a finding. Real needs scale with how big you are, how much you sweat, and how hot it is where you live. The US National Academies put adequate total water at 3.7 litres a day for men and 2.7 litres for women, with about 80% of that coming from drinks and the other 20% from food. This calculator works out the drinking part from your body weight, then adds for exercise, heat and creatine.
| Factor | Effect on your daily target |
|---|---|
| Body weight | About 35 ml per kilogram, or roughly half your weight in pounds as ounces |
| Exercise | About 300 ml, or 10 oz, for every 30 minutes |
| Warm climate | Around 500 ml, or 17 oz, a day |
| Hot climate | Around 1 litre, or 34 oz, a day |
| Creatine | Around 500 ml, or 17 oz, a day |
How much water to drink with creatine
Creatine pulls water into your muscle cells, which is part of how it works. That water has to come from somewhere, so the usual guidance is an extra 300 to 500 ml, roughly 12 to 16 ounces, for every 5 gram dose. On a normal maintenance dose that is about half a litre a day on top of your usual intake, which is what this calculator adds when you switch creatine on.
During a loading phase you are taking four doses a day rather than one, so aim for an extra litre instead. The cramping people blame on creatine is usually just under-drinking while taking it.
Thirst is a reasonable guide for most people, and pale straw-coloured urine is a better day-to-day check than any calculator. This tool gives a target, not a prescription. If you have kidney or heart problems, or you are on medication that affects fluid balance, ask a doctor rather than a website.
Creatine draws water into muscle. If you take it, your target goes up.
Naked Creatine