Estimate the amount of plywood or OSB needed for sheathing a gable roof.
This will also work for a Hip roof. The square metres of a Hip roof area is identical to the square metres of a Gable roof of the same measurements.

The length measurements are in metres, the overhangs in millimetres. The amount of plywood needed is based on sheets 1200 x 2400 millimetres. One sheet = 2..88 square metres.

Instructions

1. building length in metres
2. building width, the "gable side" wall in metres
3. gable overhang in millimetres
4. eaves over hang in millimetres
5. waste factor in a percentage preset @ 10%

The Results

1. roof area in square metres
2. number of sheets needed based on exact square metres of the roof
3. the number of sheets the waste percentage will add
4. Number of sheets needed including the waste