Free Guide to Chainsaw File Sizes and Chain Matching

Understanding Chainsaw File Basics and Why Size Matters

A chainsaw file is a specialized tool designed to sharpen the teeth on a chainsaw chain. Unlike regular files, chainsaw files have a specific round shape that matches the curved cutting edges of chainsaw teeth. When you use your chainsaw regularly, the teeth gradually become dull from cutting through wood, dirt, and other materials. A dull chain makes your saw work harder, produces more sawdust than actual chips, and requires you to push down with more force to cut. Using the correct file size ensures you sharpen each tooth at the proper angle and depth, which keeps your chain cutting efficiently and safely.

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File size is measured in millimeters and refers to the diameter of the round file. The most common sizes used in chainsaws are 4.0mm, 4.8mm, 5.5mm, 5.8mm, and 7.2mm. Each chainsaw chain is manufactured with teeth of a specific design, and the teeth require a matching file size to be sharpened correctly. Using a file that is too small will not remove enough metal from the tooth, leaving a dull edge. Using a file that is too large can remove too much material and change the tooth shape, reducing cutting performance and potentially causing safety issues.

The relationship between file size and chain type is direct and important. Chains with smaller teeth need smaller files, while chains with larger teeth need larger files. This is not a matter of preference or approximation—it is a technical specification set by the chainsaw and chain manufacturers. Matching your file to your chain type ensures that when you sharpen, you are maintaining the original geometry of the tooth, preserving the strength of the cutting edge, and keeping the chain balanced so it cuts straight without pulling to one side.

Practical Takeaway: Before purchasing a file or sharpening your chain, locate the chain model or pitch information on your chainsaw or chain package. Write this information down so you can reference it when selecting the correct file size. This simple step prevents purchasing the wrong tool and ensures your sharpening efforts actually improve cutting performance.

How to Identify Your Chainsaw Chain Type and Pitch

Every chainsaw chain has identifying information stamped or printed on the side links. The pitch is one of the most important pieces of information, as it directly determines the file size you need. Pitch refers to the distance between three consecutive rivets on the chain, divided by two. The most common pitches are .325 inches, .375 inches (also called 3/8 inch), and .404 inches. Some older or specialty saws may use different pitches, but these three cover the vast majority of chainsaws in use today.

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To find your chain's pitch, look at the side of your chain and find three rivets in a row. Measure the distance between the first rivet and the third rivet using a ruler or measuring tape marked in inches. Divide this measurement by two to get the pitch. For example, if the distance between the first and third rivet is .65 inches, your pitch is .325 inches. Alternatively, you can look at the chain itself—the manufacturer usually stamps the pitch directly on the chain. Common stamps look like ".325" or "3/8" printed on the metal.

The gauge is another specification you should note. Gauge refers to the thickness of the drive links—the small teeth that fit into the groove on the chainsaw bar. Common gauges are .050 inches, .058 inches, and .063 inches. While gauge does not directly determine file size, it helps you order the exact replacement chain and confirms you have the correct chain for your saw. Write down both the pitch and gauge along with the chain length (measured in inches from the tip of the bar to the back).

You can also find this information in your chainsaw's owner's manual or on the manufacturer's website. If your manual is missing, enter your saw's model number into a search engine along with the words "chain specifications" to find documentation online. Many chainsaw manufacturers post specification sheets that list compatible chain types and their corresponding file sizes. Some retailers' websites also have lookup tools where you enter your saw model and it shows you compatible chains and the file sizes needed.

Practical Takeaway: Create a reference card for your chainsaw by writing down the model number, chain pitch, chain gauge, bar length, and required file size. Store this card in a waterproof pocket near where you keep your chainsaw tools. When you need to purchase a replacement chain or file, you have the correct information immediately available without having to search for your manual or measure the chain again.

File Size Matching Chart for Common Chainsaw Chains

Below is a reference guide that shows the relationship between common chainsaw chain pitches and the file sizes that match them. This chart covers the chains used in the majority of residential and semi-professional chainsaws. Keep in mind that within each pitch category, there may be variations in tooth design that could affect sharpening, but the file size remains consistent for chains of the same pitch.

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.325 inch pitch chains use a 4.0mm round file. This is the most common pitch found on residential chainsaws with engine sizes ranging from 30cc to 50cc. Chains with .325 pitch are designed for general purpose cutting and are popular on Stihl, Husqvarna, Echo, and many other consumer-grade saws. The 4.0mm file is small enough to fit precisely into the tooth gullet without binding or removing too much material.

.375 inch pitch chains (also called 3/8 inch low-profile or 3/8LP) use a 4.8mm round file. This pitch is found on mid-range residential and light professional saws typically in the 50cc to 70cc range. The 3/8 low-profile design offers a balance between cutting speed and vibration control. Some older or professional chains with .375 pitch may specify a different file size, so check your chain packaging or manual.

.375 inch full-chisel chains (also labeled 3/8" or .375") use either a 5.5mm or 5.8mm round file depending on the specific chain design. Full-chisel chains have more aggressive tooth geometry and are typically found on professional-grade and forestry saws in the 60cc range and larger. These chains cut faster than low-profile variants but produce more vibration. The larger file size reflects the larger tooth design of these chains.

.404 inch pitch chains use a 7.2mm round file. These chains are found on larger professional saws and specialty equipment designed for heavy duty cutting. The .404 pitch is less common in home use but is the standard for many forestry and arborist saws. The significantly larger file size matches the substantial tooth structure of these chains.

Practical Takeaway: Bookmark or print this section for reference. When you purchase a new chain or file, match your chain's pitch to this chart to confirm you have selected the right file size. If your chain pitch does not appear on this list, check the chain packaging or the manufacturer's website for specifications, as some specialty chains or older models may use different sizes.

Step-by-Step Process for Measuring and Selecting the Right File

Once you know your chain pitch and have identified the corresponding file size, selecting the actual file is straightforward. When you go to a hardware store, home improvement center, or online retailer, you will see chainsaw files organized by size. Files are available in individual tools or as part of sharpening kits that include a handle, depth gauge tool, and sometimes a guide to help you maintain the correct angle while sharpening.

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When examining a file in person, look at the diameter of the round file itself. The diameter should be marked on the package or handle. Confirm it matches your required size—for example, if you need a 4.8mm file for your .375 pitch chain, make sure the package clearly states "4.8mm" or "3/8 inch" (these are often used interchangeably for this size). Do not rely on visual estimation. Files that are one size off can damage your chain teeth or leave them insufficiently sharp.

When ordering online, read the product description carefully. Reputable retailers list the file size prominently in the title and description. If you are purchasing a sharpening kit rather than a single file, confirm that it includes the correct file size for your chain. Some kits are universal and include multiple files, while others