The basic process: loosen, remove, install, tension, tighten

Replacing a chainsaw chain takes about 10 to 15 minutes once you know the steps. You will loosen the side cover (or both covers on some models), slide out the old chain, fit the new one onto the sprocket and bar, set the tension so it does not sag, and tighten everything back down. The whole job requires only the tools that came with your saw — usually a wrench and a screwdriver — and no special skills.

The reason to replace a chain is wear: a dull chain that does not cut cleanly, a chain with bent or broken teeth, or one that has stretched so much that no amount of tensioning brings it back. A new chain costs between $30 and $80 depending on the bar length and saw model. Doing the work yourself saves the $50 to $100 labour cost at a shop.

Key Takeaways

  • You need the bar length and chain pitch (usually stamped on the bar or in your manual) to order the correct replacement chain.
  • The side cover comes off with one or two bolts; on some saws you remove the spark plug wire first to prevent accidental starting.
  • The new chain slides onto the sprocket at the nose of the bar and must sit in the groove that runs around the bar's edge.
  • Proper tension means the chain pulls away from the bar by about one-quarter inch when you tug it by hand, then snaps back when you let go.
  • Tighten the cover bolts firmly but not with full force — over-tightening can crack the cover or strip the bolts.

Find the right chain for your saw

Every chainsaw chain is made for a specific bar length and pitch. The bar length is the distance from the tip of the bar to where it enters the saw body — usually 14, 16, 18, 20, or 24 inches. The pitch is the distance between the teeth, measured in fractions of an inch. Most consumer saws use 0.325-inch or 3/8-inch pitch.

You will find this information in three places: stamped on the bar itself (look on the side or underside), printed in your owner's manual, or on a label inside the fuel cap or on the engine. Write down both numbers before you order. Ordering the wrong pitch or length means the chain will not fit, and you cannot return it.

When you buy the replacement, you will also see a number like 52 or 56 — that is the link count, which the seller will match to your bar length. You do not need to count the links yourself; the shop or online retailer will do that once you give them the bar length and pitch.

Remove the side cover and old chain

Lay the saw on a flat surface with the engine off and cool. On most saws, disconnect the spark plug wire by pulling the rubber boot off the spark plug — this prevents the engine from starting if you accidentally bump the throttle. Some saws have a kill switch you can use instead.

Locate the side cover bolts. Most saws have one or two bolts on the side cover nearest the chain. Use the wrench that came with your saw (usually 8 mm or 10 mm) to turn them counterclockwise. On some models, the cover is held by a single bolt with a spring underneath; on others, there are two bolts. Remove the cover completely and set it aside with the bolts in a safe place.

Once the cover is off, you will see the chain wrapped around the bar and sprocket. Loosen the bar mounting bolts — usually two bolts that hold the bar to the engine body — by turning them counterclockwise about one-quarter turn each. Do not remove them completely; you just need to free the bar so it can slide forward slightly. Slide the bar forward to release tension on the old chain, then lift the chain off the sprocket and bar and set it aside.

Install the new chain on the bar and sprocket

Before you fit the new chain, check that the sprocket teeth are not cracked or badly worn. If they are, the sprocket should be replaced at the same time as the chain — a worn sprocket will wear out a new chain in a few hours of cutting. If the sprocket looks good, proceed.

Take the new chain and loop it around the sprocket at the nose of the bar, making sure the teeth point in the direction the old chain was running (usually clockwise when you look at the saw from the right side). The chain must sit in the groove that runs around the edge of the bar — if it is sitting on top of the bar instead of in the groove, you have it backwards or it is the wrong pitch.

Once the chain is on the sprocket and in the groove all the way around the bar, slide the bar back toward the engine body until the chain is snug but not tight. Tighten the two bar mounting bolts by hand — turn them clockwise until they are snug, but do not use the wrench yet. You will fine-tune the tension in the next step.

Set the chain tension correctly

Proper tension is critical. A chain that is too loose will derail during cutting and can damage the bar. A chain that is too tight will wear out the sprocket and bearings and make the saw hard to start. The correct tension is when the chain pulls away from the bar by about one-quarter inch (roughly the thickness of a dime) when you tug it by hand, then snaps back when you let go.

To adjust, locate the tension screw on the side of the engine body, usually near the bar mounting bolts. It is often a flathead or Phillips screw. Turn it clockwise to tighten the chain or counterclockwise to loosen it. Make small adjustments — one-quarter turn at a time — and test the tension by hand after each turn. Once the chain pulls away by about one-quarter inch and snaps back, you are done.

Some saws have a tool-free tensioner that you turn by hand instead of with a screwdriver. The principle is the same: adjust until the chain has the right amount of play.

Tighten the cover and test

Once the tension is set, tighten the two bar mounting bolts firmly with the wrench. Turn them clockwise until they are snug — you want them tight enough that the bar does not move, but not so tight that you are straining. If you over-tighten, you can crack the cover or strip the bolt threads.

Slide the side cover back into place and insert the bolts. Tighten them by hand first, then use the wrench to snug them down. Again, firm is good; over-tight is bad. Reconnect the spark plug wire by pushing the rubber boot back onto the spark plug.

Start the saw and let it run for 30 seconds at idle. Stop it and let it cool for a minute, then check the tension again by hand. New chains stretch slightly during the first few minutes of running, so you may need to tighten it one more time. After that, the tension should hold steady until the chain wears out.

Frequently Asked Questions

What if the chain keeps coming off during cutting?

The chain is too loose. Stop the saw, let it cool, and tighten the tension screw one-quarter turn at a time until the chain no longer derails. If tightening does not help, the bar may be bent or the sprocket may be worn — both require professional repair.

Can I use a chain from a different brand of saw?

No. The pitch and bar length must match exactly. A chain from a different brand will fit only if it has the same pitch and link count. Check the numbers on both chains before you buy.

How often do I need to replace the chain?

It depends on how much you cut and what you cut. A chain used occasionally on softwood may last a season or more. Heavy use or cutting dirty wood (which dulls the teeth faster) may require a new chain every few months. Replace it when it no longer cuts cleanly or when you notice teeth are bent or missing.

Do I need to replace the sprocket when I replace the chain?

Not always, but a worn sprocket will wear out a new chain quickly. If the sprocket teeth are smooth, rounded, or cracked, replace it. If the teeth are still sharp and defined, the sprocket is fine to reuse.

What is the difference between a sharp chain and a dull one?

A sharp chain cuts cleanly and pulls itself into the wood with minimal pressure. A dull chain requires you to push hard and produces fine sawdust instead of chips. Dull chains can be sharpened with a round file, but once the teeth are bent or broken, the chain must be replaced.