Here is a list of great formulas you might need around your pond!
Electricity
Watts = Current (amps) * Voltage (120v / 230v)
Amps = Power (watts) * Voltage (120v / 230v)
Liner Size
Length = (depth * 2) + Length + 3
Width = (depth * 2) + Width + 3
Pump Size per Pond Gallons
Gallons Per Hour (GPH) = Volume * 2
Surface Area
Square Pond = Length * Width
Circular Pond = Top Diameter * Bottom Diameter * Total Depth * 5.9
Oval Pond = (Oval Length * .5) * (( Oval Width * .5) * 3.14
Water Volume
Square or Rectangular Pond = Length * Width * Average Depth * 7.48
Circular Pond = Diameter * Diameter * Average Depth * 5.9
Oval Pond = Length * Width * Depth * 6.7
Average Depth = (Shallowest Point + Deepest Point) / 2