Chainsaw Repair

.404 X 2 = .808

7/8 = .875/2 = .437 which is not a valid chain size

3/8 = .375 X 2 = 3/4  so if the chain measured 3/4" across three rivets it would be 3/8"  pitch

.325 X 2 = .650 and if the chain measured a little more than 5/8" across three rivets it would be .325 chain

When you look at the rivets and their spacing, there is a short interval and a long interval between the rivets. So you have to add up a long interval and a short interval and divide by two to get the chain pitch.