30° top plate, 85° side plate — that's the standard for most chains

For most standard chainsaw chains, you should file the top plate at 30° and the side plate at 85°.

Those are the numbers that chain manufacturers use for general cross-cutting. The 30° top plate angle controls how aggressively the tooth bites into the wood — it’s the best all-around compromise between speed and smoothness. The 85° side plate angle is the file’s tilt relative to the direction of the chain, which keeps the side plate cutting edge sharp and properly shaped.

What matters more than memorizing the exact degree is using a filing guide or clamp that locks the file at those angles. Hand-filing freehand is how you end up with a chain that looks sharp but won’t cut straight. If your chain is unusual — a ripping chain, skip-tooth, or something with a micro-profile — check the box or the manufacturer’s spec sheet. But for a standard 3/8" or .325" chain doing normal work, 30° and 85° is your answer.

Get yourself a cheap filing gauge if you don’t have one. It’s the difference between a sharp chain and just making noise.