If it is square or rectangle, then it is as easy as length x width x average depth (measured at the mid point between the shallow and the deep ends (in metres) x 1000 = volume in litres.
So… 8 x 4 x 1.2 x 1000 = 38400 litres).
For an irregular pool – round, oval or kidney-shaped – the same formula applies: length x width x average depth. It won’t be completely accurate, but it will be close
If you happen to be filling an empty pool, calculate it’s volume by noting how long it takes to fill it.
When you take the hose out, keep it flowing at the same rate and see how long it takes to fill a smaller container (10 or 20 litres), then apply this easy calculation:
Example: 10 hours and 10 minutes = 600 + 10 = 610 Minutes to fill.
15 Seconds to fill a 10 litre container.
The Hosepipe flow rate is 40 litres per minute x 610 = 24 400 litres.