Replace the chain yourself in 30 minutes with basic tools

A chainsaw chain dulls or breaks with use, and replacing it is a job you can do at home without special equipment. You need a wrench (usually 10mm or 13mm, depending on your saw), a new chain that matches your bar length and pitch, and about 30 minutes. The process is the same across most consumer chainsaws: loosen the side cover, remove the old chain, thread the new one onto the sprocket, and tension it so it sits snug against the bar.

The hardest part is not the replacement itself but buying the right chain. Chainsaws are picky about fit — a chain that is too loose will derail, and one that is too tight will burn out the motor. You need to know your bar length (usually printed on the saw or the original packaging) and your chain pitch, which is the distance between the rivets that hold the chain links together. Most consumer saws use either .325-inch or 3/8-inch pitch. If you have the old chain, measure three rivets and divide by two to find the pitch.

Key Takeaways

  • Buy a replacement chain that matches your bar length and pitch — measure the old chain or check your manual if you are unsure.
  • Loosen the side cover bolts and remove the old chain by hand once the tension is released.
  • Thread the new chain onto the sprocket with the sharp edges facing forward, then tighten the cover bolts in a cross pattern to avoid binding.
  • Adjust chain tension so it sits snug against the bar with no slack — you should not be able to pull it more than a quarter-inch away from the bar.
  • Check the tension again after five minutes of running the saw, because new chains settle and may need a second adjustment.

Gather your tools and the right replacement chain

Before you start, turn off the saw and let it cool for at least 10 minutes. Unplug it if it is electric, or remove the spark plug wire if it is gas-powered. This prevents accidental starting while your hands are near the chain.

Lay the saw on a flat surface with the bar pointing away from you. Look at the side cover — the metal plate that holds the chain in place. You will see two or three bolts holding it on. Check your manual or the saw itself to find the wrench size; most chainsaws use 10mm or 13mm. Have that wrench ready, along with your new chain.

If you do not know what chain to buy, take the old one to a hardware store or chainsaw dealer. They can match it by length and pitch in seconds. A new chain costs between $20 and $60 depending on bar length and brand.

Remove the side cover and old chain

Loosen the two or three bolts on the side cover by turning them counterclockwise. Do not remove them completely — just loosen them enough that the cover moves freely. As you loosen the bolts, you will feel the chain tension release. Once the cover is loose, you can usually slide it away from the bar by hand.

The old chain will now hang loose on the sprocket. Lift it off the sprocket teeth and pull it away from the bar. Set it aside. You may see a small metal sprocket at the center of the bar — this is the drive sprocket, and the new chain will wrap around it just like the old one did.

Wipe the bar and sprocket area with a dry cloth to remove any sawdust or old oil. This makes it easier to see what you are doing when you thread the new chain on.

Thread the new chain onto the sprocket and bar

Hold the new chain so the sharp cutting edges face forward (toward the tip of the bar). Starting at the sprocket, drape the chain over the drive sprocket teeth. The chain should sit in the groove that runs around the bar — you will feel it settle into place.

Work your way around the bar, making sure the chain sits evenly in the groove on both sides. The chain should not twist or bunch up. Once it is threaded all the way around, the two ends of the chain will meet near the sprocket. They should overlap slightly — if they do not, you have the wrong chain length.

Slide the side cover back into place and insert the bolts. Tighten them by hand first, then use your wrench to snug them down. Do not crank hard — you are just closing the cover, not crushing it. Tighten in a cross pattern (top bolt, then bottom bolt, then top again) to keep the cover from binding.

Adjust the chain tension

Once the cover is snug, you need to set the chain tension. Loosen the bolts on the side cover just slightly — enough that the cover can move a little but not so much that it falls off. This lets you adjust the chain without fighting the cover.

Look for the tension adjustment screw. On most saws, it is a small screw on the side cover near the bar tip. Turn it clockwise to tighten the chain, counterclockwise to loosen it. The goal is a snug fit: the chain should not sag away from the bar, but you should be able to pull it away from the bar by about a quarter-inch at the midpoint. If you pull it and it does not move at all, it is too tight.

Once the tension feels right, tighten the side cover bolts all the way down in a cross pattern. Tighten the top bolt, then the bottom, then back to the top. This keeps the cover from pulling crooked and throwing off your tension adjustment.

Run the saw and re-check the tension

Start the saw and let it run at idle for about five minutes. New chains stretch slightly as they warm up and the links settle. After five minutes, turn off the saw, let it cool for two minutes, and check the tension again. You may need to loosen the cover bolts slightly and turn the adjustment screw a quarter-turn to keep the chain snug.

This second check is important — a chain that is too loose after the first run will derail and throw the chain off the bar, which is dangerous and damages the saw. A chain that is too tight will overheat the motor and dull the teeth faster.

Once the tension is set and the saw runs smoothly, you are done. The chain will need sharpening after 5 to 10 hours of cutting, depending on what you are cutting. A dull chain pulls to one side and requires more pressure to cut — that is your signal to sharpen or replace it.

Frequently Asked Questions

What if the new chain does not fit around the bar?

You bought the wrong pitch or length. Take the chain back and bring the bar with you so the store can match it correctly. Pitch is the most common mistake — a 3/8-inch chain will not fit on a .325-inch bar, even though they look similar.

Can I use a different brand of chain than the original?

Yes. Any chain with the correct pitch and length will work. Brand does not matter as long as the specs match. Some chains cost more because they stay sharp longer or have better safety features, but a budget chain will cut just fine.

How tight should the chain actually be?

Tight enough that it does not sag, but loose enough to move. Grab the chain at the midpoint of the bar and pull it away. It should move about a quarter-inch. If it does not move at all, loosen the adjustment screw a bit. If it sags more than a quarter-inch, tighten it.

What happens if I run the saw with a loose chain?

A loose chain will derail and fly off the bar, which can injure you and damage the saw. It may also slip on the sprocket and fail to cut. Always check tension before and after the first few minutes of running a new chain.

Do I need to add oil when I replace the chain?

No. The oil reservoir is separate from the chain itself. Check your oil level before you start cutting, but replacing the chain does not affect the oil system.