SawingPros is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you.

How To Measure a Chainsaw Bar

Last updated on:

When it’s time to replace the chain on your chainsaw you’ll need to know the length of the chain.  If you don’t know, can’t find the owner’s manual for your chainsaw, or if the chain is broken or lost, you’ll need to measure the bar the chain goes on.  With this information, you can get the correct chain for your chainsaw.

There are two ways to measure the length of the bar on your chainsaw.  You can measure the effective length or the true length.  There will be several inches in difference from one to the other.

Effective Length

The bar measurement, or effective cutting length, is shorter than the actual length of the bar.  This is the simplest measurement to take.  All you’ll need is a standard tape measure.  This length is also sometimes referred to as the chainsaw length.

Since you’re going to be handling the chain itself, a couple of safety steps are prudent before beginning the measuring process.  Turn the chainsaw off.  Grasp the rubber boot that covers the spark plug and remove the wire from the spark plug by gently pulling on it until it comes free.  This will prevent the chainsaw from coming on, even by accident.

Lay the chainsaw down and place the end of the tape measure against the body of the chainsaw where the bar emerges from the casing.  Stretch the tape out to the end of the bar and slightly past the end.  You want to measure to the tip of the cutter that sticks the furthest out from the tip of the bar.  If the chain is missing, you can estimate about 1/2″ further from the tip of the bar.


Round the measurement to the nearest inch.  For example, you measured 15-7/8″ round it up to 16″.  You have a 16″ chainsaw.

True Length

The true length is exactly what it sounds like – the true length of the bar itself from one end to the other.  To get this measurement you’ll have to use a socket driver and/or wrench set to remove the bolts holding the cover on the chainsaw.

Remove the cover completely.  This will expose the entire chainsaw bar. It will also leave it lying loosely across the body of the chainsaw. Lift the chainsaw bar off the interior bolts and lay it down flat.

Put the end of the tape measure at one end of the bar itself.  Don’t worry about the chain on this measurement.  Stretch the tape to the other end of the actual bar and read the measurement.  There won’t be any need to round off the measurement, and it will be the true length of the bar.

chainsaw on the grass

When you go to the store to purchase a new chain or a new bar, for your chainsaw, bring these measurements with you.  The chainsaw length will be the first one you measured.  The bar length will be the second one.

Once you have the new bar or chain, replace the old one.  Put the chain on the bar and set the bar on the interior bolts of the chainsaw.  You may need to adjust it for tensioning before replacing the cover (see your owner’s manual), then bolt the cover back in place.

Other chainsaw posts we’ve written: