A 5/32 chainsaw file is the correct size for sharpening most standard chainsaw chains

A 5/32 chainsaw file is a round file designed to sharpen the cutting teeth on chainsaw chains. The "5/32" refers to the diameter of the file in inches — this size matches the gullet (the curved space between teeth) on chains made for saws with engines between 30 and 60 cubic centimeters. If your chainsaw manual does not specify a file size, 5/32 is the most common choice for homeowner and small commercial saws.

The file works by hand — you position it inside each tooth's gullet and stroke it in one direction to restore the cutting edge. A sharp chain cuts faster, produces finer sawdust, and requires less pressure from you. A dull chain pulls to one side, produces large chips, and forces the engine to work harder, which can damage the saw over time.

Key Takeaways

  • A 5/32 file sharpens chains on most standard chainsaws; check your manual to confirm this is the right size for your saw.
  • You will need the file itself, a file holder or guide to keep the angle correct, and a way to find the chain so it does not move while you work.
  • Each tooth gets the same number of strokes in the same direction, and you sharpen every tooth before moving to the next step.
  • A chain that pulls to one side or produces large chips instead of fine sawdust is a sign it needs sharpening.

Confirm the 5/32 size matches your chainsaw

The file size depends on the pitch and gauge of your chain, not the engine size of your saw. The pitch is the distance between rivets on the chain, and the gauge is the thickness of the drive links. Most homeowner chainsaws use a chain with a pitch of 3/8 inch or .325 inch, and a 5/32 file works for both of these common pitches.

Your chainsaw manual will list the correct file size in the maintenance section. If you no longer have the manual, look for a label on the saw itself or search online using your saw's model number. If you buy a file that is too small, it will not reach the full depth of the gullet and will not sharpen the tooth properly. If the file is too large, it will not fit inside the gullet at all.

Gather the tools you will need

Beyond the 5/32 file itself, you need a way to hold the file at the correct angle and a way to keep the chain from moving. A file holder or filing guide is a metal bracket that clamps onto the file and rests against the tooth and the bar of the chainsaw, holding the file at the correct angle automatically. These cost between $15 and $40 and are sold at hardware stores and online retailers that carry chainsaw supplies.

You also need to find the chainsaw so the chain cannot turn while you file. Clamp the saw in a bench vise, or rest it on a sturdy work surface and have someone hold it steady. Some people use a wooden block wedged against the chain to lock it in place. Make sure the chain is tight enough that it does not move when you explore pressure with the file.

A depth gauge (also called a go-no-go gauge) is optional but useful. It measures the height of the raker tooth, which is the small tooth in front of each cutting tooth that controls how deep the saw bites into the wood. If the raker is too high, the saw will not cut aggressively; if it is too low, the saw will bite too hard and may kick back. A depth gauge costs $5 to $15.

Position the file and sharpen each tooth

Start at one end of the chain and work your way around. Place the file holder on the file, then position the file inside the gullet of the first tooth. The file should sit perpendicular to the bar of the saw — that is, at a right angle to the length of the bar. The file holder will rest against the top of the tooth and the bar, keeping the angle correct.

Push the file forward and upward in one smooth stroke, using light to medium pressure. Do not pull the file backward — the cutting happens only on the forward stroke. Lift the file away from the tooth at the end of the stroke and return it to the starting position without dragging it backward across the tooth. Repeat this forward stroke the same number of times for each tooth — typically 3 to 5 strokes, depending on how dull the chain is.

Move to the next tooth and repeat. Work your way around the entire chain, sharpening every cutting tooth the same way. You will notice metal shavings accumulating in the gullet; brush these away with your hand or a small brush so you can see what you are doing. Once you have sharpened all the teeth on one side of the chain, rotate the saw and sharpen all the teeth on the other side.

Check and adjust the raker teeth

The raker teeth are the small teeth positioned in front of each cutting tooth. They do not have a sharp edge; instead, they control the depth of cut. If the rakers are too high, the saw will not cut aggressively. If they are too low, the saw will bite too hard and may cause kickback or pull to one side.

Use a depth gauge to measure each raker. Place the gauge flat on top of the raker tooth, with the step of the gauge resting on the cutting tooth behind it. If the raker is higher than the step on the gauge, use a flat file to file the top of the raker down until it is level with the gauge. File in one direction only, just as you did with the round file on the cutting teeth. The exact depth varies by chain type, but most rakers should be between 0.025 and 0.035 inches below the cutting tooth.

Test the sharpened chain on wood

Once you have sharpened all the teeth and adjusted the rakers, reinstall the chain on the saw and tighten it according to your manual. The chain should be snug enough that you cannot pull it away from the bar by hand, but loose enough that it spins freely when you turn it by hand.

Start the saw and make a test cut on a piece of scrap wood. A sharp chain will cut quickly and produce fine sawdust that falls away from the cut. A dull chain will produce large chips and require you to push hard on the saw. If the chain pulls to one side, one side may have been sharpened more than the other, or the rakers may not be even. You can make minor adjustments by sharpening the duller side a few more strokes, or you can take the saw to a professional sharpening service.

Know when to sharpen and when to replace

A chainsaw chain will dull faster if you hit dirt, rocks, or metal while cutting. Cutting wet wood also dulls the chain faster than cutting dry wood. If you use your saw regularly, you may need to sharpen the chain every few hours of use, or even more often if you are cutting in dirty conditions.

A chain that has been sharpened many times will eventually become too short or too damaged to sharpen further. If the teeth are broken, cracked, or worn down to a nub, or if the chain has stretched so much that it no longer stays tight on the bar, it is time to replace the chain. A new chain costs between $20 and $60 depending on the length and pitch.

Frequently Asked Questions

What if I do not have a file holder?

You can sharpen without a holder, but the angle will be harder to keep consistent. Hold the file at roughly a 30-degree angle to the bar and try to keep that angle the same for every stroke on every tooth. A file holder removes the guesswork and produces a sharper, more even result. They are inexpensive and worth buying if you plan to sharpen your chain more than once.

How many strokes should I use on each tooth?

Start with 3 strokes per tooth. If the chain is very dull, you may need 5 or 6 strokes. If the chain is only slightly dull, 2 or 3 strokes may be enough. The key is to use the same number of strokes on every tooth so the chain sharpens evenly and does not pull to one side.

Can I use a 5/32 file on a different size chain?

No. A file that is too small will not reach the full depth of the gullet, and a file that is too large will not fit inside the gullet at all. Using the wrong size will either leave the chain dull or damage the file. Always check your manual to confirm the correct file size for your chain.

What is the difference between a round file and a flat file?

The round file (5/32 or whatever size matches your chain) sharpens the cutting teeth. The flat file sharpens the raker teeth and is used to adjust their height. Most chainsaw sharpening kits include both files.

How do I know if my chain is too dull to sharpen?

If the teeth are visibly broken, cracked, or worn down to a stub, the chain cannot be sharpened back to usefulness. If the chain has stretched so much that it sags on the bar even when tight, it is also time to replace it. Otherwise, almost any dull chain can be sharpened with a file.