How to measure your wall.
Using a measuring tape and have your partner or friend assist you with holding one end of the tape, for an accurate measurement.
Measure the height and width of the wall to the nearest centimeter excluding the skirting and cornicing.
“Measure twice or often measure three times and then have someone else to double check your measurement just to make sure”
Please have a look at the below diagram for the measurement of different types of walls and walls with obstructions.