Water Intake Calculator

How much water should you drink a day?

A simple, widely used rule of thumb is to drink about half an ounce of water for every pound you weigh. So a 160 lb person starts at roughly 80 ounces (about 10 cups) on a normal day. This calculator uses that half-ounce-per-pound baseline, then adds extra water for the fluid you lose while exercising.

Why exercise adds to the total

When you sweat, you lose water that needs replacing. A common guideline is to add about 12 ounces of water for every 30 minutes of activity. If you work out for an hour, that is roughly an extra 24 ounces on top of your baseline. Hot weather, high altitude, illness, pregnancy, and breastfeeding can all push your real needs higher, so treat the number here as a friendly starting point rather than a hard target.

How to use it

1. Enter your body weight in pounds.
2. Enter how many minutes you plan to exercise today.
3. Read your estimated daily water in ounces, cups, and litres — the results update instantly as you type.
4. Spread that amount across the day and sip more if you feel thirsty or notice dark urine.

These figures are estimates for general wellness, not medical advice. Ask your doctor if you have kidney, heart, or other health conditions that affect fluid intake.

FAQ

Do coffee and tea count toward my water?

Mostly yes. Despite their reputation, moderate caffeinated drinks still hydrate you. Plain water is best, but food and other beverages contribute too.

Can I drink too much water?

It is rare, but drinking huge amounts very quickly can dilute your blood sodium. Spread your intake out and don't force far beyond thirst.

Should I use my current weight or goal weight?

Use your current weight — the estimate is based on the body you're hydrating right now.

Why show cups and litres too?

Different bottles and habits use different units. Cups (8 oz each) and litres make it easy to match your water bottle or tracking app.