Bar, Chain & Sprocket: What Everything Means

Every chainsaw bar, chain, and drive sprocket has three specs that all have to match: pitch, gauge, and drive link count. If any one of them is wrong the chain won't fit, or worse, it fits but runs badly.

The three specs that have to match

Pitch and gauge are fixed by your saw model. Drive link count depends on bar length, so that one changes when you switch to a longer or shorter bar.

Pitch

Pitch is the spacing between drive links. It's measured as the distance between three consecutive rivets divided by two. Common values:

3/8" LP (low profile): most battery and light homeowner saws. Husqvarna calls it "3/8 Picco", Oregon calls it "91" series.
.325": common on mid-size Husqvarna saws and some older Stihls. Smaller than standard 3/8".
3/8": the standard pitch for most gas farm and pro saws. Stihl MS250 and up, Husqvarna 455 and up.
.404": large pro saws only (Stihl MS660, Husqvarna 576 XP and similar). Heavier chain, higher-displacement engines.

3/8" LP and 3/8" look similar in print but they are not the same pitch and they will not interchange. The drive sprocket on your saw is machined for one specific pitch.

Where to find it: Stamped on the bar near the mount end, on the drive sprocket cover, or in your owner's manual.

Gauge

Gauge is the thickness of the drive links, which ride in the bar groove. The bar groove is machined to a specific width and the chain drive links have to match it exactly.

.043": most battery saws and small homeowner models (Stihl MS170/MS180, some Husqvarna 120 series)
.050": the most common gauge, used by most mid-range gas saws
.058": some mid and pro-size Husqvarna saws
.063": pro saws and large bars, often paired with .404" pitch

Too thin and the chain rattles and jumps in the groove. Too thick and it won't fit at all.

Where to find it: Stamped on the bar rail near the mount, or on the chain drive links with a loupe or good light. Your manual lists it too.

Drive links

Drive links are the tangs on the bottom of the chain that ride in the bar groove and engage the sprocket. The drive link count tells you how long the chain is and it has to match the bar you're using.

A 16" bar takes a chain with a specific drive link count. An 18" bar takes more. The count is different for every combination of bar length and pitch. You can't just buy "a 16 inch chain" without the exact count.

Where to find it: Printed on your current chain's packaging. If you don't have the packaging, count the drive links by hand: they are the inner teeth that ride in the groove, not the cutters.

The bar

The bar is the metal plate the chain rides around. It has a groove machined to a specific gauge, and a nose sprocket at the tip. Bars are rated for specific pitches, gauges, and lengths.

Your saw also has a bar mount shape, a physical slot in the saw body where the bar attaches. Stihl, Husqvarna, and Echo all use different mount shapes, so bars are not interchangeable between brands even if the pitch and gauge match. Oregon and other aftermarket bar makers sell bars for each mount type.

The sprocket

The drive sprocket sits behind the bar mount and engages the chain drive links. It has teeth machined for a specific pitch. Swap to the wrong pitch chain and the teeth won't mesh and the chain won't move.

There are two types: spur sprockets (a solid star bolted to the clutch drum) and rim sprockets (a replaceable ring that snaps onto the clutch drum). Rim sprockets are more common on mid and pro saws and are designed to be swapped without replacing the whole clutch assembly.

A worn sprocket will destroy a new chain fast. If the sprocket teeth are hooked or the valleys are worn smooth, replace it when you put on a new chain.

Cutter style

Cutter style describes the shape of the cutting teeth. The main ones:

Full chisel: square-cornered cutters, aggressive, cuts fast, dulls faster, more kickback risk
Semi-chisel: rounded corners, stays sharp longer, tolerates dirt better, cuts a bit slower
Low-kickback: extra safety features that reduce kickback, required on consumer saws sold in some markets

For regular firewood and cleanup work, semi-chisel is easier to live with. Full chisel is faster in clean softwood. Pitch and gauge still have to match regardless of cutter style.

What happens when specs don't match

Wrong pitch: chain won't engage the sprocket, or skips and jumps under load.

Wrong gauge: chain won't fit in the bar groove, or rattles loose and can derail or throw.

Wrong drive link count: chain won't seat properly on the sprocket and bar, can derail, and puts stress on the bar nose.

Safety: A chain that doesn't fit properly can throw, damage your bar and sprocket, and cause serious injury. Always verify pitch, gauge, and drive link count before running a new chain.

How to use this tool

Pick your saw in the Saw Lookup tab. It will show you every bar and chain that fits, filtered by mount type, pitch, gauge, and bar length range. You can also use the Part Checker if you already have a part number and want to know what it fits.

If your saw isn't listed yet, send an email and it will get added: admin@sawchainmatch.com