It is best to measure or pace out the perimeter of your boundary. This will give you an idea of how much wire will be required. You will also have to measure the distance from the fenceline to where the transmitter will be located (remember, it has to be out of the weather and able to be plugged in), and double this measurement. Click on the link below for a guide to the amount of wire required based on the acreage you want to cover (This is an estimate only but it would be advisable to pace out your property).
Calculate the wire you need with this guide