Pitch

To work out the pitch measurement you are going to need a tape measure. To get the correct size, simply count 3 rivets on the chain and measure the distance between them from the centre points. Now divide this by half to get your size. As an example, three rivets that measure ½ an inch across divided by two gives you a pitch of a ¼ inch. Make sure you check your chainsaw (on the guide bar) and the instruction manual for the measurements too, as these are typically located in one of these two places.

Gauge

This is the thickness of the drive links (the tooth-like underside of the chain that fits in the guide bar). The chain gauge is measured in inches and will usually be in the manual or on the chainsaw itself. As it is difficult to measure accurately with a tape measure, you may need a vernier caliper to get this measurement. There are four different gauge sizes, which are .043, 0.50, .058, .063, with the lower sizes being the most common. If you select the wrong size, it may be too thick to fit your chainsaw or too loose to gain proper traction.

Drive Links

This is the most mundane part of the measurement process, but also one of the most important. To get a chain that is the correct size you need to count the drive links (those little teeth on the underside of the chain). One tip is to place a strip of tape on the first link and count your way around. You need to know exactly how many there are to get the correct chain size for your chainsaw. Now you have those three numbers, you can begin your search for the chain that you need.