If you don't have this piece of information then you need to calculate it. This is easy enough if the pool is a nice rectangular or circular shape. If however you have a pool that is a complicated shape then it is much more difficult.

Here is a resource to help you and to convert units into those most useful to you. As mains water is supplied in Britain in cubic metres, start by measuring in metres to obtain an answer in cubic metres. Then use the calculator to convert this figure into litres, imperial gallons or US gallons.

Rectangles and Squares

Simple Rectangular Pool
meters   feet
Enter dimensions of pool	Metres		Feet	Inches		Volume of water
Length (L):						cu metres:
Width (W):						litres:
Minimum Depth (D1):						imp gallons:
Maximum Depth (D2):						us gallons:
(If the pool has a flat bottom, enter the same figure for max and min depth.)

         

If your pool has a sloping bottom, then take the deepest measurement (D1) and the shallowest (D2). If there are different levels, then you need to do several calculations of area for each depth and add them up at the end.

Circles

Circular Pool
meters   feet
Dimensions of pool	Metres		Feet	Inches		Volume of water
Diameter (d):						cu metres:
Minimum Depth (D1):						litres:
Maximum Depth (D2):						imp gallons:
						us gallons:
(If the pool has a flat bottom, enter the same figure for max and min depth.)

Ellipses

Eliptical Pool
meters   feet
Enter dimensions of pool	Metres		Feet	Inches		Volume of water
Major Diameter (a):						cu metres:
Minor Diameter (b):						litres:
Minimum Depth (D1):						imp gallons:
Maximum Depth: (D2)						us gallons:
(If the pool has a flat bottom, enter the same figure for max and min depth.)

 

Irregular shapes

4)
Example of "counting squares" method of approximately calculating the area of an irregular shape.

For irregular shapes, calculating the area is less accurate. You will need to draw up the pool accurately to scale on graph paper using a square on the paper to represent a meter (or foot) square of pool. When you have finished, count the squares. For partial squares, count anything over half as one and ignore any under a half. When you have the area (A) multiply by depth (D) for the Volume in cubic metres. If you have several depths, break up your area calculation for each depth.

Irregular Pool
meters   feet
Enter dimensions of pool	Metres		Feet	Inches		Volume of water
Area (A):						cu metres:
Depth (D):						litres:
						imp gallons:
						us gallons:
(If you have several depths, break up your area calculation for each depth.)

Conversion into different units
 

1 Metre = 3.2808399 Feet

You can easily convert units using this calculator

(Results are rounded to 4 decimal places)

cubic metres to litres - Multiply by 1000
cubic metres:		litres:
cubic metres to UK gallons - Multiply by 219.969
cubic metres:		UK gallons:
UK gallons to litres - Multiply by 4.54609
UK gallons:		litres:
US gallons to litres - Multiply by 3.785411
US gallons:		litres:
UK gallons to US gallons - Multiply by 1.20095
UK gallons:		US gallons:
US gallons to UK gallons - Multiply by 0.832674
US gallons:		UK gallons: