Koi

To work out the gallonage of a square or rectangular pond

• In feet and inches: length x width x depth x 6.23 = gallons
For example, a pond that’s 8ft x 8ft x 5ft deep = 8 x 8 x 5 x 6.23 = 1993.6 gallons

• In metres: length x width x depth = the m3 measurement, then x 220 (because there are 220 gallons or 1,000 lpm3)
For example, a pond that is 2.5m long by 2.5m wide x 1.5m deep = 9.375m3, x 220 = 2062.5 gallons

To work out the gallonage of a circular pond
• In feet and inches: radius (half of the diameter) squared (times by itself) x pi (3.14) x depth x 6.23 = gallons
For example, a pond with a diameter of 10ft will have a radius of 5ft, and a depth of 5ft deep would give you 5 x 5 = 25 (radius squared) x 3.14 (pi) = 78.5. 78.5 x 5 (depth) = 392.50, and 392.50 x 6.23 = 2445.27 gallons

• In metres: radius (half of the diameter) squared (times by itself) x pi (3.14) x depth x 220 = gallons
For example, a pond with a diameter of 3m would have a radius of 1.5m, and a depth of 1.5m deep would give you 1.5 x 1.5 (radius squared) x 3.14 (pi) = 7.065. 7.065 x 1.5 (depth) = 10.5975m3, and 10.5975 x 220 = 2331.45 gallons (because each m3 holds 220 gallons or 1000l)

If you want to work out these figures in litres, one gallon is equal to 4.546l. So a pond of 2445.27 gallons holds 11116.197l, and a pond of 2331.45 gallons holds 10598.77l.

If your pond is an unusual shape or has varying levels of depth, draw it onto graph paper and then divide it up into zones of equal depth or that are a more uniform shape. Having done this, apply the formulas shown to work out the gallonage of each zone, then add them all together to give you the total gallonage.