Free tool
Chainsaw Chain & File Size Finder
Find the right round file size for your chain pitch, decode the pitch, gauge and drive-link numbers stamped on your bar, and estimate the chain loop for a bar length.
Bar fits are typical, not guaranteed: drive link counts vary by bar maker and sprocket. Always read the pitch, gauge and drive link count stamped on your bar.
Chain, bars and sharpening gear
Pitch, gauge and drive links
Every chain is described by three numbers. Pitch is the size of the chain (the distance between any three rivets divided by two), gauge is the thickness of the drive links that ride in the bar groove, and the drive link count sets the loop length. All three must match your bar and sprocket. They are stamped on the bar tail, and most chain boxes print them too.
File size follows pitch: the wrong file either fails to sharpen the full cutter or changes the hook of the tooth. Use a file guide to hold the right depth and angle.
Common questions
What file size for 3/8 chain?
Standard 3/8" pitch chain is usually sharpened with a 7/32" (5.5 mm) file. 3/8" low-profile chain uses 5/32" (4.0 mm), and .325" chain uses 3/16" (4.8 mm). Check the chain maker’s chart for your exact chain.
How do I count drive links?
Lay the chain flat and count the tangs that point inward, the parts that ride in the bar groove. Mark your starting link with a marker so you do not lose count.