What Size Chainsaw File for 3/8 Chain? (Direct Answer + Full Guide)

Quick Answer: What Size File for a 3/8 Chainsaw Chain?

A standard 3/8-inch pitch chainsaw chain requires a 13/64-inch (5.2 mm) round file for sharpening full-chisel and semi-chisel cutters. The 3/8 Low Profile (LP) chain — also called Picco — is a separate specification and requires a smaller 5/32-inch (4.0 mm) round file. These two chains share part of the same name but are not interchangeable, and using the wrong file diameter produces uneven, ineffective sharpening.

Before purchasing a file, confirm the exact chain designation stamped on the drive link. The sections below explain how to do that, what the numbers mean, and how to sharpen correctly once you have the right file.

Understanding Chainsaw Chain Pitch and Why It Determines File Size

What “3/8 Pitch” Means

Chain pitch is the average distance between any three consecutive rivets divided by two. On a 3/8-inch pitch chain, that measurement equals 0.375 inches. Pitch determines the physical size of each cutter link — specifically the height, curvature, and gullet geometry of the tooth. A round sharpening file must match that geometry precisely: too small and it sits too deep in the tooth and cuts the wrong profile; too large and it rides on top of the cutter and removes too little metal.

Why 3/8 Standard and 3/8 LP Are Different Chains

This is the single most common source of error when selecting a chainsaw file. Both chains carry “3/8” in their name, but they are engineered for different saws and different applications:

• 3/8-inch pitch (standard): Used on mid- to full-size professional and semi-professional saws. Cutters are physically larger. Requires a 13/64-inch (5.2 mm) round file.
• 3/8-inch Low Profile (LP) / Picco: Designed for lightweight consumer saws, electric saws, and pole saws. Cutters are smaller with a reduced-height design. Requires a 5/32-inch (4.0 mm) round file.

The LP designation is printed or stamped on the drive link and is also reflected in the chain’s Oregon or Stihl part number. If you see “LP,” “Picco,” or a suffix like “33” in the Oregon chain numbering system, you have 3/8 LP — not standard 3/8.

How Pitch Affects Cutter Geometry

A larger pitch means a longer cutter with a wider, taller tooth profile. The round file must fit snugly inside the curved cutting edge (the gullet) so that one-quarter to one-third of the file diameter sits above the top plate of the cutter. If the file is undersized, it sharpens only the bottom of the gullet. If oversized, it rounds off the top plate and destroys the cutting hook angle. File diameter is not a rough guideline — it is a precision match to cutter geometry.

Chainsaw File Size Chart: Pitch to File Diameter Reference

Use this table to cross-reference your chain pitch with the correct round file diameter. Confirm pitch from the chain itself before relying on this chart.

Note: A 13/64-inch file and a 5.2 mm file are the same diameter. Manufacturers list both measurements; either specification on the file package is correct for standard 3/8 chain.

How to Confirm Your Chain Specification Before Buying a File

Step 1 — Read the Drive Link Stamp

Turn the chain over and examine the drive link (the tooth that runs in the bar groove). Most chains stamp a code directly into the metal. On Oregon chains, this is typically a two-digit number. On Stihl chains, it is a letter or letter-number combination. Examples:

• Oregon code 72 = 3/8-inch standard pitch, .050-inch gauge → requires 13/64-inch (5.2 mm) file
• Oregon code 91 = 3/8 LP Picco, .050-inch gauge → requires 5/32-inch (4.0 mm) file
• Stihl code PM3 = Picco Micro 3, 3/8 LP → requires 4.0 mm file

Cross-reference the stamped code against the Oregon Drive Link Identification Chart or the Stihl chain specifications page on the respective manufacturer’s website.

Step 2 — Check the Guide Bar

Many guide bars have the pitch and gauge laser-etched or stamped near the heel (the end that mounts to the saw body). This confirms the chain pitch the bar is designed for. However, this does not substitute for reading the chain itself, because chains can be swapped.

Step 3 — Consult the Saw’s Owner Manual or Manufacturer Website

Enter your saw’s model number on the Stihl, Husqvarna, or Oregon website to pull the OEM chain specification. This lists pitch, gauge, and the recommended file diameter explicitly. This method is reliable only if the original chain has not been replaced with a different specification.

Step 4 — Measure Pitch Manually

Lay the chain flat on a work surface. Using a caliper or ruler, measure the distance between the centers of three consecutive rivets, then divide by two. A result of approximately 0.375 inches confirms 3/8-inch pitch. This does not distinguish standard from LP — for that, the drive link stamp is essential.

How to Sharpen a 3/8 Chainsaw Chain with a Round File

Tools Required

• 13/64-inch (5.2 mm) round file (for standard 3/8 chain)
• File holder / filing guide set to the correct angle
• Flat file for depth gauge (raker) adjustment
• Depth gauge tool (raker gauge)
• Bar vise or bench vise to secure the saw

Step 1 — Secure the Saw and Engage the Chain Brake

Clamp the bar in a vise or use a dedicated bar-mount vise. Engage the chain brake. The chain must be immobile during filing. Wear cut-resistant gloves — cutter teeth are sharp even when dull by performance standards.

Step 2 — Set the Correct Filing Angle

Filing angle requirements for 3/8-inch chain:

• Top plate filing angle (horizontal): 25–35 degrees, depending on cutter type and manufacturer specification. Full-chisel cutters are typically filed at 30–35 degrees. Semi-chisel cutters are typically filed at 25–30 degrees. Confirm the angle in your chain’s specification sheet.
• File tilt angle (vertical): Hold the file level (0 degrees tilt) for most standard applications, unless the manufacturer specifies a slight downward tilt (typically 10 degrees down) for specific cutter profiles.

A filing guide or angle guide slipped over the file before sharpening removes guesswork and maintains consistency across every tooth. This is strongly recommended for anyone not sharpening chains regularly.

Step 3 — Position the File Correctly in the Cutter

Place the round file in the gullet (curved inside edge) of the cutter so that approximately one-fifth of the file diameter sits above the top plate of the cutter. For a 13/64-inch file, this means roughly 1 mm of the file is above the tooth’s flat top surface. This positioning ensures the file sharpens the correct geometry without lowering the top plate excessively.

Step 4 — File Each Cutter with Consistent Strokes

File in one direction only — push strokes away from the body, lifting the file on the return stroke. Apply light, even pressure. Use 3 to 5 strokes per tooth when maintaining a chain in good condition. Use more strokes only if the cutter is significantly damaged or rounded. Count strokes and keep the number identical for every cutter to maintain uniform tooth length. File all cutters on one side first, then rotate and file the opposite side.

Step 5 — File the Depth Gauges (Rakers)

The depth gauge (raker) is the curved leading edge in front of each cutter. It controls how deeply the cutter bites into wood. If the raker is too tall relative to the cutter, the chain will not cut efficiently even when cutters are sharp. The standard depth gauge clearance for most 3/8-inch chains is 0.025 inches (0.635 mm), though some aggressive cutting profiles use 0.030 inches. Verify the correct clearance in your chain’s specification documentation.

Use a flat depth gauge tool (raker gauge) placed over the chain. If the raker protrudes above the tool’s slot, file it flush using a flat file. Round the front of the raker slightly after filing to restore the original profile and prevent grabbing.

Step 6 — Inspect and Test

After sharpening, all cutters should be equal in length and show a consistent shiny edge on the top plate and face. Reinstall the chain at the correct tension, run the saw briefly at idle, then make a test cut. A properly sharpened 3/8 chain pulls itself into wood with minimal downward pressure and produces uniform chips — not dust — in the kerf.

Signs Your 3/8 Chain Needs Sharpening and When to Replace It Instead

Sharpening Indicators

• The saw requires heavy downward pressure to cut — a sharp chain feeds itself.
• The kerf produces fine sawdust rather than coarse wood chips.
• The cut drifts to one side, indicating uneven cutter lengths (one side filed more than the other over time).
• Visible rounding or light reflection on the cutter face when viewed under direct light.
• Increased vibration during cutting — dull teeth impact rather than slice.

When to Replace Rather Than Sharpen

A 3/8-inch chain can be sharpened multiple times throughout its service life, but each sharpening removes metal and shortens the cutter. Replace the chain when:

• Cutter length has been reduced to 4 mm or less from the front of the tie strap. Most chains have a wear indicator line stamped or molded into the cutter; once the tooth is filed back to that line, the chain is at end of service life.
• Drive links show cracks, bent tangs, or visible stretching — these are structural failures that sharpening cannot correct.
• The chain has contacted soil, rocks, or wire. Embedded grit causes micro-fracturing of the cutter edge that dulls the chain within seconds of resuming cutting. Inspect cutters under magnification; if the edge is jagged rather than smooth, replacement is more efficient than attempting recovery.
• The chain is stretched beyond the tensioner’s adjustment range and cannot be brought to correct tension.

Over-filing — removing excessive metal to compensate for deep nicks in a single sharpening session — dramatically shortens chain life and distorts cutter geometry. When a cutter is deeply damaged, replace the chain rather than grinding it down.

Frequently Asked Questions

Is a 13/64-inch file the same as a 5.2 mm file?

Yes. 13/64 inches converts to approximately 5.156 mm, which manufacturers round to 5.2 mm. Both labels refer to the same file and are correct for standard 3/8-inch pitch chainsaw chain. Purchase either — the physical file is identical.

How do I tell if my chain is 3/8 standard or 3/8 Low Profile (Picco)?

Read the stamp on the drive link. Oregon LP chains typically carry a drive link code of 90, 91, or 95. Stihl LP chains carry a Picco designation in the chain part number (e.g., PMX, PM3). If you see “LP,” “LowPro,” or “Picco” anywhere on the chain packaging or part number, use a 5/32-inch (4.0 mm) file, not the 13/64-inch file for standard 3/8 chain.

What angle do I file a 3/8 chainsaw chain at?

Standard 3/8 full-chisel chain is typically filed at 30–35 degrees horizontal top-plate angle. Semi-chisel chain is typically filed at 25–30 degrees. The exact specification is listed in the chain manufacturer’s sharpening guide and on most filing guide packages. Confirm the angle for your specific chain rather than defaulting to a generic figure.

How often should I sharpen a 3/8 chainsaw chain?

Sharpening frequency depends on material and conditions, not a fixed interval. Sharpen whenever the saw requires downward pressure to feed, produces dust instead of chips, or the cut begins to drift. Many professional operators touch up the chain after every tank of fuel in heavy use. A single contact with soil or rock warrants immediate inspection and sharpening before the next cut.