How many bathtubs does it take to fill an Olympic pool?
"Olympic-sized swimming pools" turn up in the news every time something involves a lot of water. But how much is one, really?
An Olympic pool is 50 metres long and at least 25 metres wide, and at the 2.5-metre minimum depth the Olympics require it holds 3,125,000 L. A bathtub filled to the brim, by the American Water Works Association's count, holds 70 gal.
So filling an Olympic pool takes about 12,000 bathtubs.
How long would that take?
If you could fill, carry and tip one bathtub every minute, without a break, you would be pouring for more than a week. Most pools are filled from a fire hydrant instead.
Bigger than you think, smaller than you'd guess
That's a lot of baths, but a pool is a surprisingly small amount of water by the standards of the news stories that use it. A big reservoir holds millions of them. Next time a headline says "enough to fill 400 Olympic pools", you can do the conversion yourself on the comparison page.
Sources
- bathtub, volume: 70 gal. Village of Pleasant Prairie: Water Facts (from the American Water Works Association), retrieved November 11, 2026. A full bathtub, US gallons.
- Olympic swimming pool, volume: 3,125,000 L. World Aquatics: Swimming Pool Certification (Facilities Rules, Part 2, 15.3 and 15.4), retrieved November 11, 2026. 50 m × 25 m × 2.5 m, the Olympic minimum depth; deeper pools hold more.
How we calculate: methodology.