To get the most out of this Pond Liner Calculator, you need to first find the pond’s longest length, widest width, and deepest point. This calculator rounds up the inputs to the nearest half.

The “string method” is the best way to get an accurate measurement.

You can use a regular tape measure, but by laying a piece of string across the floor so that it physically hugs every shelf and curve, you can get a better idea of the ground’s true shape instead of just measuring the air above it.

It is important to measure the actual excavation instead of the planned water level because the liner needs to fit the shape of the ground perfectly so it doesn’t stretch. Once you have these numbers, which you can get from your string or a careful tape measure, just pick your units and type them in.

The tool will automatically double the depth and add it to your surface measurements to compensate for the material moving down one bank and back up the other. The final number also includes a 0.5m “tuck” allowance, which is the “skirt” that keeps the liner in place under heavy rocks or paving at the edge.