Luntrack · Free tools · Water

Water intake
calculator.

A daily water target that grows with your training — how much to drink back after a run, ride or gym session, and how much salt went with the sweat.

lb
min
How much do you sweat?
Conditions
Salt marks on your clothes?

Fill in the form to see your result.

Drink today
—

including food and all drinks

Daily baseline
Extra for training
Sodium lost in sweat

Track it every day. Luntrack uses this exact method and adjusts as your weight and training change.

Download on theApp Store
How it's calculated

The method,
in plain words.

A daily baseline

2.5 L (about 85 oz) of fluid a day, from food and drink, is a sensible baseline for most adults.

Sweat from training

Sweat rate rises with effort, body size, how much you naturally sweat and the heat: about 1.2 L an hour for a 70 kg runner in mild weather.

Drink back 125%

You keep losing water while you rehydrate, so replacing 1.25× what you sweated is the low end of sports-science advice.

Sodium too

Each litre of sweat carries around 950 mg of sodium (up to 1,600 mg if you're a salty sweater — white marks on your cap).

For general fitness guidance only — not medical advice. If you're pregnant, have a medical condition or take medication that affects appetite or fluids, check with a doctor first.

FAQ

Good questions.

Do I really need 8 glasses of water a day?

Roughly — 2.5 L of total fluid is close to that, and food and other drinks count toward it.

How do I know if I'm drinking enough?

Pale-yellow urine and rarely feeling thirsty are good signs. Dark urine, headaches and fatigue suggest you need more.

Should I drink electrolytes?

After long or very sweaty sessions, yes — water alone doesn't replace the sodium you lost. For a short gym session, a normal meal covers it.

Does Luntrack adjust my water target?

Yes. When you run, ride or train, the app raises that day's water and sodium targets using this same model.