Can I drink too much water?

Rare but yes — hyponatremia (low blood sodium) from drinking many litres in a short time without electrolytes. Most common in marathon runners. Spread intake across the day.

Why dark urine when I drink lots?

Vitamins (especially B-complex) and beets can make urine darker even when hydrated. Also: morning urine is concentrated regardless. Use color throughout the day, not first morning, as the indicator.

Water Intake Calculator

Daily hydration needs by bodyweight + exercise + climate.

Result

Daily water target

3.13 L

In litres3.13 L
In US fl oz106 oz
In 8 oz cups~13.2 cups
In 500 mL bottles~6.3 bottles
Per hour while awake (16 hr)195 mL

How to use this calculator

Enter your bodyweight.
Add average exercise minutes per day.
Pick your typical climate.
Sip throughout the day — don't try to chug it all at once.

About this tool

The "8 glasses a day" rule is a rough starting point, not a precise prescription. A better baseline: 35 mL per kg of bodyweight (about 0.5 oz per pound). Add ~500 mL for every 30 minutes of exercise. Hot and humid climates increase needs by 20–35%. This includes water from all sources — coffee, tea, soft drinks, and food contribute. Listen to your body: pale-yellow urine usually means well-hydrated; dark yellow means drink more. Overdrinking water is rare but possible (hyponatremia), most often during long endurance events without electrolyte replacement.

Frequently asked

Yes. The old "diuretic, cancels out" myth is false — caffeinated drinks net you about 80% of their water content as hydration. Plain water is still ideal but tea and coffee count.