Tips for Measuring a Chainsaw Bar and Chain

Updated: Sep. 30, 2021

If you need to buy a new chainsaw bar or chain, it's important to find the perfect fit. Here's how to measure the size of your bar and chain.

Chainsaws are versatile tools, great for light pruning, cutting up firewood and more. With all that use, eventually you’ll need to replace your chainsaw bar or chain. But before you buy, know the exact size of each. “Using the wrong size bar or chain can damage the chainsaw and injure the chainsaw operator,” says Vince Christofora of Woodstock Hardware.

Read on to learn how to measure your chainsaw’s bar and chain. It’s not hard to do and saves time at the hardware store. “Don’t bring the dirty, sawdust- and oil-clumped, gas exhaust-smelling chainsaw into the store and put it up on the counter and ask for help,” Chirstofora says. “Not a good way to start things off!”

How To Measure a Chainsaw Bar

Chainsaws are sold in even-numbered lengths, based the length of the chainsaw bar. Sometimes called a chainsaw blade, the chainsaw bar is the metal “arm” that holds and supports the chain during cutting. So when you’re buying a 16-inch chainsaw, you’re buying one with a 16-inch bar.

You can measure a chainsaw bar two ways. The most common, Christofora says, is the effective cutting length. That’s the distance from the tip of the bar to the front of the chainsaw body, where the bar disappears into the saw.

To measure a chainsaw’s effective cutting length (or simply, “length”):

  1. Place a tape measure at the very tip of the bar.
  2. Measure straight back to the point where the bar enters the chainsaw body.
  3. Round that measurement up to the nearest even number.

Because chainsaws are only sold in even numbers, you’ll need to round up odd numbers and fractions. A saw with a 15-inch effective cutting length is a 16-inch chainsaw. If you measure 18-3/4-in., it’s a 20-inch saw.

The true bar length is a second, less commonly used measurement. If you need this to get a perfect fit for your replacement bar, here’s how to do it:

  1. Loosen the bolts that hold the bar to the chainsaw body.
  2. Remove the bar and place it on a flat surface.
  3. Measure the bar, end to end.

The chainsaw true bar length is a precise measurement. Don’t round this number up.

How to determine a chainsaw bar groove gauge

If you’re buying a new chainsaw bar, Christofora says you may also need to know the gauge of the bar groove. Here’s how to find it:

  1. Gather a penny, dime and quarter.
  2. Insert the coins into the bar groove one at a time.
  3. Determine which coin best fits into the groove.

“For close approximations, you can use a quarter for .063 inch, a dime for .058 inch and a penny for .043 inch,” Christofora says. Another option: Purchase an inexpensive gauge, which helps you measure chain pitch, chain gauge and file size, too.

How To Measure a Chainsaw Chain

chainsaw chainBilanol/Getty Images

Your best bet when purchasing a new chainsaw chain? Search for a replacement based on your chainsaw’s manufacturer and model number.

It pays to be precise here, Christofora says. “Most times when a customer comes into the store they just try to buy a chain the same length.” he says. “But chains, even the same length, vary by chainsaw manufacturer.” If you know the manufacturer and model number, you can cross-reference it with the information listed on the chainsaw chain packaging.

It doesn’t hurt to write or engrave the numbers on the chain saw bar, near the saw’s body, too. They reflect the chain pitch, the number of driver links and the chain link gauge. If you need these numbers and can’t locate them, or if they’ve worn off, you can measure each ofto determine its size.

How to measure the chain pitch

The chain pitch refers to the distance between the chain’s links. Here’s how to measure it.

  1. Using a ruler or measuring tape, measure the distance between three of the rivets on your chain.
  2. Divide that measurement by two. The resulting figure is your chain pitch.

Common chain pitches include 1/4-in., .325-in., 3/8-in. and .404-in.

How to measure the driver links

Determining the number of driver links is as easy as counting the links on your chain.

  1. Identify the driver chain links. They’re small bumps on the inside of the chain.
  2. Count the number of links on the chain.

How to measure the chain link gauge

Chain link gauge is the thickness of the drive links. When your chain link gauge matches the gauge of your chainsaw bar, the chain fits snugly. You can use a caliper or an inexpensive multi-purpose gauge to measure this.

  1. Place your caliper or gauge along the groove where the chain fits into the bar.
  2. Write down the reading on your caliper or gauge.

Common drive link gauges are .043-in., .050-in., .058-in. and .063-in.

Chainsaw Sizing Guide

Having the right size chainsaw for the job makes cutting easier and safer.

Sizes often vary according to the type of chainsaw, each good for different jobs. The most common chainsaw bar sizes are 12 to 20 inches, but they come in sizes as large as 72 inches, typically for professionals. The longer the bar, the heavier the chainsaw.

When choosing the right chainsaw size for the job, it’s best to have a chainsaw bar at least two inches longer than the thickness of the item that you’re cutting. Certain chainsaw sizes are best suited for different types of activities:

  • Gas-powered chainsaws start at 16 to 18 inches, and go up to as large as 72 inches. The 16- to 18-inch chainsaws are best for felling medium trees, while chainsaws with a 20-inch or larger bar are suitable for large trees or cutting firewood.
  • Electric chainsaws tend to be smaller, usually 14 to 16 inches. Use the 14-inch saws for felling small trees, and 16-inchers for medium trees.
  • Battery-operated saws are 16 to 18 inches, good for bringing down medium trees.
  • Small battery-operated six- to nine-inch chainsaws also exist, including the Milwaukee M12 Fuel Hatchet Six-Inch Pruning Saw. Use these for pruning small limbs.