How to Size a Chainsaw Chain (Pitch, Gauge, Links)

You size chainsaw chain by matching three numbers: pitch, gauge and drive link count. All three are usually stamped on the guide bar or listed in your owner’s manual. If you can’t find them, you can measure each one in about ten minutes with a ruler or calipers. Here is how, plus the mistakes that cause bad fits.

The three numbers that size a chainsaw chain

A chain fits only when it matches the saw’s bar and drive sprocket. Three measurements decide that:

• Pitch: the spacing of the chain’s links, which must match the sprocket teeth. Common sizes are 1/4″, 3/8″ low profile, .325″, 3/8″ and .404″.
• Gauge: the thickness of the drive link tang that rides in the bar groove. Common sizes are .043″, .050″, .058″ and .063″.
• Drive link count: the number of tangs on the underside of the chain. This sets the chain’s total length for your bar.

Bar length is a fourth number, but it only matters because it largely determines the drive link count. Two chains with the same pitch and gauge but different link counts are not interchangeable.

If you are still deciding which saw and bar length suit your yard, our guide to the best size chainsaw covers that choice first.

Where to find the numbers without measuring

Check these places before you pull out any tools. Reading the numbers is faster and more reliable than measuring.

1. The guide bar. Most bars have the length, gauge, pitch and drive link count stamped near the mounting slot or on the tail. You may need to wipe off oil and sawdust to read it.
2. The owner’s manual. The specifications page lists the correct chain pitch, gauge and drive link count for each approved bar length.
3. The old chain’s packaging or the saw’s label. Replacement chains list part numbers and specs on the package. Brand part numbers often encode the specs.
4. The chain itself. Some chains have a pitch or gauge code stamped on the drive links. Codes vary by brand, so treat them as a clue and confirm against the bar.

If the bar was swapped by a previous owner, the manual may not match what is on the saw. In that case, trust the markings on the bar and the sprocket, not the manual.

How to measure pitch, gauge and drive links

If the markings are worn off, measure each number yourself. Before you start, make sure the saw is off and unplugged, the battery is removed, or the spark plug wire is disconnected. Wear cut-resistant gloves, since even a dull chain can cut.

Measure the pitch

Pick any three rivets in a row on the chain. Measure from the center of the first rivet to the center of the third, then divide by two. That result is the pitch. Across three rivets, a 1/4″ chain measures about 1/2″, a .325″ chain about 21/32″, and a 3/8″ chain about 3/4″. A .404″ chain measures about 13/16″.

Note that 3/8″ standard and 3/8″ low profile have the same pitch. They differ in link height and are not always interchangeable, so check your bar or manual to see which one you have.

Measure the gauge

Use digital calipers on the thickness of a drive link tang, the part that sits in the bar groove. Round to the nearest standard size: .043″, .050″, .058″ or .063″. Without calipers, you can compare against a drill bit shank of known size, but calipers are more reliable because the sizes are close together.

Count the drive links

1. Lay the chain flat on a table with the tangs facing up or down.
2. Mark one drive link with a paint pen or marker.
3. Count each tang, including the marked one, going around the whole loop once.

Do the count twice. An off-by-one error is the most common reason a new chain comes out too tight or too loose.

Typical chain specs by bar length

The table below shows common combinations for popular homeowner saws. These are examples only. The same bar length can use different pitch, gauge and link counts depending on the brand and model, so always confirm against your bar or manual.

Notice the ranges. A 16″ bar on one saw may take a different chain than a 16″ bar on another. That is why bar length alone is not enough to order a chain.

The labeled bar length is also a nominal figure. The actual cutting length is usually an inch or two shorter than what is stamped, because part of the bar sits inside the saw housing.

Mistakes to avoid when buying a replacement chain

• Ordering by bar length only. You need pitch, gauge and drive link count too.
• Confusing 3/8″ and 3/8″ low profile. They share a pitch but not link height, and the wrong choice can cut poorly or fit badly.
• Guessing gauge. A chain that is too thin will wobble in the groove and wear the bar. One that is too thick will not seat at all.
• Ignoring the sprocket. If the drive sprocket does not match the chain pitch, the chain will not run correctly. Worn sprockets also damage new chains, so inspect it when you change chains.
• Forcing a chain on. If it doesn’t drop into the bar groove and around the sprocket with a little slack, it’s the wrong size. Stop and recheck your numbers.

Once the size is right, cutter style and brand come into play. Our rundown of the best chainsaw chain options is a useful next step, and homeowners shopping for a full saw can start with the best chain saws for home use.

Check fit and know when to replace instead of sharpen

After installing a new chain, check the fit before you start cutting. Make sure all drive links sit in the bar groove. With the saw off, the chain should pull freely by hand and the tie straps should not sag below the bar. Tension specs differ between saws, so follow the manual. Many saws also need a re-check after the first few cuts, since a new chain stretches as it breaks in.

A chain that is dull is not necessarily a chain that needs replacing. If the cutters are still in good shape, a quick touch-up restores the edge. Our walkthrough on how to sharpen a chainsaw chain by hand shows the steps and the correct file size, which also depends on pitch.

Replace the chain when cutters are filed down to the wear marks, when drive links are rounded or cracked, or when rivets are loose. Replace the bar too if the groove is worn or spread, since a new chain on a damaged bar will not run true.

Frequently Asked Questions

How do I know what size chain my chainsaw takes?

Look for the pitch, gauge and drive link count stamped on the guide bar near the mounting slot. If they are worn off, check the owner’s manual or measure the chain yourself with a ruler and calipers.

Can I use a different pitch chain on my saw?

Generally no. The chain pitch must match the drive sprocket and the bar nose. Using a different pitch can cause poor cutting, fast wear or a chain that won’t run. Some saws allow sprocket and bar swaps, so check the manual.

Does bar length tell me the chain size?

Not by itself. Bar length helps set the drive link count, but you also need the correct pitch and gauge. Two 16-inch bars can take different chains, so always confirm all three numbers before buying.

How do I count drive links on a chainsaw chain?

Lay the chain flat, mark one drive link, and count each tang on the underside once around the loop. The tangs are the parts that sit in the bar groove. Count twice to avoid mistakes.