Chainsaw Maintenance

We all know that keeping a machine or tool in good condition and mechanically tuned will increase its life and make it work better. Knowing how to measure a chainsaw bar and chain can increase the life and cutting performance of your chainsaw.

STIHL-chainsawKnowing how to properly measure a chainsaw chain and how to measure your chainsaw bar length can save you time and money when setting out for some new parts. Your chainsaw will not run correctly or at all if you have an oversized chain flopping around or a bar that simply does not fit your model.

It’s not as easy as just going out to your local outdoor power equipment retailer and picking up the biggest and baddest bar with the most aggressive chain and calling it a day.

There are almost endless combinations of bars and chains, all having different gauges, pitches and drive link counts.

  • So how do you determine what chain or bar your chainsaw needs?
  • How do you order a new one?

We’ve got you covered in this in-depth How-to article.

By the end you’ll know how to measure your bar utilizing 2 different methods using our chainsaw bar length guide, you’ll know the size of chain needed for your bar and how to put it on properly.

If you go to purchase a new chain without first taking the time to get the proper measurements and counts you’ll end up going to the store and the teller will start asking questions like

  •  What’s your effective bar length
  • What’s the pitch of the chain
  • What gauge is your chain

I think you get it.

Continue reading and we’ll explain it all in detail for you.

Before You Get Started

Clean workplace always comes first.

Before starting and taking your chainsaw apart it’s important to have a clean and clear workspace.

What you’ll need:

  • A table to lay your parts out
  • Chainsaw t-wrench (Comprised of a flathead screwdriver and 13 x 19mm wrench or simply have a wrench set to remove the nuts holding the casing on)
  • Engine degreaser
  • Cloth and Brush for removing dirt and grease that can build up around the chain gears.

Safety First!

Now that you go your workspace ready, there’s one more step before beginning any work on your chainsaw It’s important to follow certain safety measures, after all, chainsaws are an extremely dangerous tool if handled incorrectly.

First and foremost you want to always wear a set of gloves whenever you’re handling a chainsaw. There are many pinch points and sharp edges that can cut you.

After you have your appropriate safety gear on, next you will want to disable the chainsaw to prevent it from accidentally starting while working on it.

The easiest method to disable a chainsaw is to remove the spark plug wire from the top of the spark plug, to do so, carefully grab the rubber boot that the spark plug wire feeds into on the top of the spark plug and pull it straight off. (Sometimes a little wiggle is necessary to pop it off)

Now that your chainsaw is disabled, it’s time to get to work.

How To Measure Chainsaw Bar Length

It’s important to note, before starting to take anything apart, different manufacturers and stores can use slightly different measuring points to determine bar length.

The two measurements used are effective bar length (The length of bar sticking out past the chainsaw casing) and total bar length (The length of the bar from tip to tip)

Recording both of these numbers, in the beginning, can save a lot of time and hassle when going to purchase a new bar.


measureing-chainsaw-effective-bar-lengthMeasuring effective bar length (from casing to tip)

Before you remove the bar from the chainsaw you’ll want to get the effective bar length measurement.

Take your tape measure and measure from the point where the bar disappears into the casing.

Butt your tape measure up against the casing where the bar starts to disappear into the housing and measure to the tip of the bar.

It’s important to measure right to the tip and not off to one side.

(NOTE: If your number is a fraction or an odd number then simply round up to the nearest even number and that is your effective bar length)

Measuring the entire length of bar

measuring-total-bar-lengthNow that you have your effective bar length it’s time to get the total length of the bar, again it’s extremely important that you have removed your spark plug disabling the chainsaw from starting.

First, you’ll want to remove the clutch casing cover that is held on by 1 or 2 nuts depending on the manufacturer.

If there is currently a chain on your bar this is now the time to remove it. Slide the bar back (towards the saw) to create some slack in the chain and then remove it.

Now take your bar off the chainsaw and place on your work table. For this measurement, you’re going to take your tape and measure from one end of the bar to the other. That is your total bar length. (Again rounding to the nearest even number if it’s odd or a fraction)

Selecting a new bar

There is no “best” chainsaw bar length because it is dependant on the job needing to be performed as well as the saw specifications you’re using.

Some jobs require a large 30’’ bar while some jobs that would be impractical and you need something smaller.

Each manufacturer also has specifications on the range of bar sizes the chainsaw can safely handle, for these specs its best to reference your owner’s manual or manufacturer’s website.

The most common bar length you will find is 16 – 20’’, suitable for average work.

How to measure chainsaw chain length

When it comes time to replace a chainsaw chain you’d think it’s as simple as taking a tape measure and running it around the chain, call up your local outdoor power equipment retail and place an order, but, it’s not quite as simple.


The techniques below are perfect for measuring up an old or new chain.

Count Drive links 

The first step in determining the size of replacement chain you’ll need is to count the drive links or more commonly referred to as lugs.

The drive links are the parts of the chain that stick down and look like a shark’s tooth. These are the links that latch onto the drive sprocket (Cog) and power the chain.

Simply count the number of the teeth that go around the chain and record that number as its 1 of 3 figures that will be needed for selecting a new chain.

Measure chain pitch

Measuring-Chain-PitchSecondly, you’ll need to get the pitch of the chain. The pitch is a description of how close together the links of the chain are, it assists in making sure your chain will run smoothly over the drive gear.

Although it sounds like it’s going to be a complicated task that you’ll need to know calculus for its relatively simple and can be done very quickly.

Looking at your chain you’ll see that the drive links are riveted together. Take any 3 rivets and measure from the center of the 1st rivet to the center of the 3rd rivet.

Now take that number and divide it by 2 and you have your chains pitch, record that number and move on to step 3.

Common sizes of pitch include 1/4″, .325″, 3/8″, 3/8″ low-profile, and .404″. (3/8″ pitch chains are the most common size)

Measure Gauge

Measuring-gauge-vernier-caliperNow it’s time for the final measurement, it’s time to get the gauge of the chain.

The gauge of your chain is equal to the width of the grove in your bar.

To do this there are 2 common methods that we will explain in detail.

The first method is an exact measurement (recommended) The second is a quick and handy measurement to know that requires zero tools.

Vernier Caliper Measurement

The first measurement technique uses a Vernier caliper. A Vernier Caliper is a device commonly used by mechanics to find the exact measurements for very small parts.

To get the gauge of your chain you’ll be measuring the width of a drive link.

To do this, flip your chain upside down and grab the bottom of a drive link (sharks tooth), and measure the exact width of the drive link, this is your chains gauge.

The Coin Technique

The second technique for measuring gauge is not quite as exact but still, it can be just as effective on most chainsaws. The only downside to this technique is you’ll need to have the bar to perform this measurement, it cannot be done with only the chain.

For this, you will need a Penny, Dime and Quarter. Each one has a specific width.

  • Penny = .058 gauge
  • Dime = .050 gauge
  • Quarter = .063 gauge

First using a small flathead screwdriver or a wire brush clean out any dirt or wood chips that are inside the groove of your bar.

Starting with the thinnest coin, the dime, slide it into the bar. If it wiggles around and seems too loose, move onto the penny and follow up with the quarter if it’s loose as well.

You’re looking to slide the coin into the groove of the bar and have it be slightly snug but not where you’re having to push the coin in with effort.

So you’ll see that using the coin method can provide a very accurate gauge measurement for most chainsaws.

Common gauge sizes are .043″, .050″, .058″, and .063″. (.050’’ being the most common)