Key Takeaways
- A chainsaw chain that’s too loose can kick the saw back toward the operator or derail, while a chain that’s too tight can overheat, creating a fire hazard and causing premature wear on the saw.
- A chainsaw chain should be tight enough that it’s snug against the underside of the bar and, with the saw off, the spark plug wire, the battery or power cord disconnected and the brake disengaged, it should move freely around the bar.
- You should check chainsaw tension before you use the saw and when you stop to refuel, but a new chainsaw chain will stretch more during the first use, so you need to check the tension more frequently.
- Before you tighten your chainsaw chain, it needs to be cool, you need to be wearing heavy-duty gloves and the spark plug wire or battery needs to be disconnected or the power cord unplugged.
- Adjust the chainsaw chain tension by releasing the chain brake, loosening the bar nuts or knob, lifting the bar tip, and on most saws, turning the tensioning screw or knob clockwise to tighten the chain or counterclockwise to loosen it.
- A chainsaw chain is correctly tightened when it’s snug against the underside of the bar, has no sag and, with the saw off, the spark plug wire, battery or cord disconnected and the brake disengaged, you can move it smoothly around the bar with a screwdriver or gloved hand.
- After you tighten a chainsaw chain, retighten the bar nuts or knob and check the tension once more before reconnecting the saw to power and using the saw.
Why Chainsaw Chain Tension Matters
The right chainsaw chain tension is critical to safety. A chain that’s too loose or too tight can cause severe injuries:
- A loose chain can push the saw back at the operator and derail from the guide bar.
- A chain that’s too tight can overheat and create a fire hazard.
Chain tension also affects your work and saw, leading to poor cutting, overheating and wear on the saw, bar and sprockets.
How Tight Should a Chainsaw Chain Be?
Check the tension of your chainsaw chain before every use and each time you refuel the saw:
- The chain shouldn’t sag.
- The chain should fit snugly against the underside of the guide bar.
- With the saw off, the spark plug wire or power disconnected, and the chain brake released, the chain should move smoothly around the bar with a tool or gloved hand.
- A new chain will stretch and require more frequent tightening the first time you use it.
Adjusting a chainsaw chain is a key part of maintenance. See our guide to using and maintaining a gas chainsaw or using and maintaining a battery-powered chainsaw for more maintenance tips.
Chainsaw Maintenance Safety
Follow the chainsaw manufacturer’s instructions for use, maintenance and safety. Your manual has specific instructions, but in general, before any inspection or maintenance:
- Turn the chainsaw off and allow the saw and chain to cool.
- Disconnect the spark plug wire on a gas chainsaw or, on an electric saw, disconnect the battery or unplug the saw.
- Wear heavy-duty work gloves or chainsaw safety gloves.
Read our chainsaw safety article to learn more tips on using a chainsaw correctly.
Tightening a hot chain can cause the chain to become too tight as the metal cools and contracts.
How to Adjust a Chainsaw Chain
We’ve got general steps for loosening and tightening a chainsaw chain, but the process varies by model. Follow the steps for your saw.
Step 1: Loosen the Bar Nuts or Knob
Disengage the chain brake. Depending on the saw model, there are bar nuts or a knob securing the guide bar and drive sprocket cover. Loosen the nuts with a wrench or chainsaw scrench tool or loosen the knob by hand. Your instructions might tell you to leave the nuts hand tight or loosen the knob a half turn. Don’t loosen the nuts or knob completely.
Step 2: Adjust the Chain Tension
Lift the tip of the guide bar before adjusting the chain. If your saw has bar nuts, there’s typically an adjacent tensioning screw or a screw at the base of the bar, next to the engine. Use a screwdriver or scrench to turn the screw and tighten or loosen the chain according to your instructions. Typically, on most chainsaws:
- Turn the screw clockwise to tighten the chain.
- Turn the screw counterclockwise to loosen the chain.
If your saw has a retaining knob, there should be a tensioning wheel nearby or integrated with the knob. Turn the wheel to adjust the chain. Typically:
- Turn the wheel or knob clockwise or forward to tighten the chain.
- Turn the wheel or knob counterclockwise or backward to loosen the chain.
Step 3: Check the Chain Tension
Once the chain looks snug against the underside of the bar, pull the chain away from the bar. When you release the chain, it should snap back against the bar. With the bar supported and the chain brake disengaged, move the chain around the bar using a screwdriver, scrench or your gloved hand. It should move freely without binding or sagging. Continue to adjust the tension as necessary.
Correct tension varies depending on your saw, chain and bar. Follow the specifications for your equipment.
Step 4: Retighten the Bar Nuts or Knob
Keep the bar supported. Retighten the bar nuts or knob according to your saw instructions. Make a final tension check, pulling the chain from the bar and ensuring it snaps back and doesn’t sag. Periodically check the chain tension the next time you use the saw, adjusting as necessary.
Follow the manufacturer’s instructions for using a chainsaw. Check the bar and chain oil level. Wear safety gear, including a helmet, eye protection, hearing protection, chainsaw safety gloves and chainsaw chaps.
Find Tools and Materials to Use and Maintain Your Chainsaw
At Lowe’s, we’ve got everything you need to keep your saw safe and running smoothly. Shop Lowes.com for chainsaw chains, bars, maintenance tools, safety gear and more. Or stop by your local Lowe’s and talk to a Lowe’s Red Vest associate. From bar and chain oil to sharpening tools and new chains, they’ll make sure you have everything you need for the next job.