What do the numbers stamped on a chainsaw drive link mean?

Stihl etches the chain's identity right on the drive link: the pitch code digit on the upper left and the gauge code digit on the lower right. Gauge codes run 1 = .043 inch, 3 = .050 inch, 5 = .058 inch, 6 = .063 inch, and 0 = .080 inch (harvester chain only).

What happens if I run a chain with the wrong pitch?

Pitch determines how the drive links seat in the notches of the drive sprocket. A chain with the wrong pitch will not mesh properly with the sprocket — it will ride rough, wear both parts rapidly, and can jump or break. If your sprocket has visible grooves worn into it, replace the sprocket before installing a new chain.

What is a chain loop?

At the parts counter, a pre-cut, factory-assembled length of chain is often called a loop. When ordering, always identify the chain by its part number or by all three measurements — pitch, gauge, and drive link count — rather than by the slang term.

How do I know when my chainsaw chain is worn out?

Each cutter has a wear indicator line etched into its top. Every sharpening files the cutter back, and once you have filed down to that line the chain is worn out and should be replaced — there is not enough tooth left to cut safely past the line.

Can I put any bar on my chainsaw as long as it mounts?

No. The chain's pitch must match the drive sprocket and the chain's gauge must match the bar's groove. Changing pitch may also require changing the sprocket so the whole drivetrain matches.

Chainsaw Reference • Parts Counter Series

Chainsaw Chain Identification Chart

Q: How do I identify my chainsaw chain size?

Every chainsaw chain is identified by three measurements: pitch (the distance between three rivets divided by two), gauge (the thickness of the drive link), and the drive link count (how many drive links it takes to go around the bar and drive sprocket). On a Stihl guide bar, all three are etched right on the bar along with the bar's part number.

Q: Can I put a different gauge chain on my bar?

No. Gauge is the thickness of the drive link and it has to match the width of the groove in your guide bar. A chain that is too thin will wobble and cut crooked; one that is too thick will not seat in the groove at all.

Q: Is there a tool that measures chainsaw chain pitch and gauge?

Yes. The Granberg Pitch-N-Gauge saw chain check tool (Rotary part number 4248) is a flat gauge that checks pitch, drive link gauge, bar groove, file size, depth gauge settings, and filing angles in one tool. A digital caliper also works for measuring pitch and gauge manually.

Q: What is the difference between a spur sprocket and a rim sprocket?

A spur sprocket is a one-piece star standard on homeowner saws. A rim sprocket is a replaceable rim on a splined drum, standard on professional saws. On rim sprockets, tooth count is a tuning choice: a .325-7 runs slower with more torque, while a .325-8 runs higher chain speed with less torque.

By Brandon · Updated July 2026

Three numbers identify every chain ever made: pitch, gauge, and drive link count. Here’s how to find them, how to measure them, and how to read what Stihl already etched on your bar.

Heads up: some links on this page are affiliate links. If you buy through them, Choice Lawn Parts may earn a small commission at no extra cost to you. It’s how we keep the lights on and the chains sharp.

The Three Numbers That Identify Any Chain

After eighteen years behind a parts counter, I can tell you the number one reason people walk out with the wrong chain: they describe it instead of measuring it. “It’s for a 16-inch Stihl” narrows it down to about six different chains. What actually identifies a chain, any chain, any brand, is three measurements:

Measurement	What It Is	Why It Matters
Pitch	The distance between any three rivets, divided by two. Rivets are what hold the links of the chain together.	Determines how the drive links seat in the notches of the drive sprocket. Wrong pitch = the chain won’t mesh with the sprocket.
Gauge	The thickness of the drive link — the tooth that hangs down below the chain.	Determines how the chain sits down in the groove of the guide bar. Wrong gauge = wobble, crooked cuts, or a chain that won’t seat at all.
Drive Links	The count of drive links it takes to go all the way around the bar and drive sprocket.	Determines the length of the chain. Bar length alone isn’t enough, two 16″ bars can take different drive link counts.

Counter tip: a pre-cut, factory-assembled length of chain is what you’ll hear called a “loop” at the counter. This is fine for shop talk but when you order, always go by the part number or by all three measurements above. That’s the only way to guarantee a match.

Good News: If You Have a Stihl Bar, It’s Etched Right On It

Stihl stamps everything you need directly into the guide bar near the mount end. You’ll find the bar’s part number, the bar length (in centimeters and inches), the drive link count, the pitch, and the gauge all in one line of etching.

Diagram of the information etched on a Stihl guide bar: part number, bar length, drive link count, pitch, and gauge — Everything etched on a Stihl guide bar: part number, length, drive link count, pitch, and gauge.

Here’s a real example. Bar part number 3005 000 4813 reads out like this:

Etching	Meaning
3005 000 4813	The bar’s own Stihl part number, this is what you order a replacement bar by.
40cm / 16″	Bar length.
55x	Drive link count, this bar takes a 55 drive link chain.
3/8″P	Pitch — 3/8″ Picco (Stihl’s low-profile 3/8″).
1.3mm / 0.050″	Gauge.

No bar handy, or the etching is worn off? No problem. The next two sections show you how to measure pitch and read gauge straight off the chain itself.

Pitch: How the Chain Fits the Drive Sprocket

Pitch is the spacing of the chain. It controls how the drive teeth fit into the notches of the drive sprocket. The links of a chain are held together by rivets, and pitch is measured off those rivets:

Pitch = the distance between the centers of any three rivets, divided by two.

Measuring pitch on the side profile of a chain: three rivet centers, divided by two.

Stihl encodes pitch as a single digit. It’s the first digit in the number on a Stihl chain box:

Pitch Code	Pitch	Notes
1	1/4″	Small saws, carving bars.
2	.325″	Common on mid-size homeowner and farm saws.
3	3/8″	Full-size 3/8″ — standard on professional saws.
4	.404″	Large professional and harvester applications.
6	3/8″P (Picco)	Stihl’s low-profile 3/8″ — very common on consumer saws.
7	1/4″P (Picco)	Low-profile 1/4″ — small top-handle and battery saws.

Check your sprocket while you’re at it. The drive teeth of the chain ride in the notches of the sprocket. If the sprocket has grooves worn into it, replace it. A worn sprocket will chew up a brand-new chain in short order. And a wrong-pitch chain will never seat properly in those notches in the first place, no matter how new the sprocket is.

Gauge: How the Chain Sits in the Bar Groove

Gauge is the thickness of the drive link, the tooth hanging below the chain that rides down inside the groove of the guide bar. It has to match the bar’s groove width. Stihl etches the gauge code digit right on the drive link (lower right corner, with the pitch code digit on the upper left), so you can identify gauge on a bare chain with no packaging and no bar:

Diagram showing the gauge code etched on a chainsaw drive link and the gauge code table — The gauge code is stamped directly on the drive link.

Stamp on Drive Link	Gauge	Metric
1	.043″	1.1 mm
3	.050″	1.3 mm
5	.058″	1.5 mm
6	.063″	1.6 mm
0	.080″	2.0 mm — harvester chain only

Rule of thumb: gauge is a hard match. Too thin and the chain wobbles in the groove and cuts crooked; too thick and it won’t seat at all. There’s no “close enough” on gauge.

Drive Links: The Length of the Chain

The third number is the simplest: count the drive links. The quantity it takes to go all the way around the bar and the drive sprocket is the chain’s length. Bar length in inches is not a substitute, because two bars of the same advertised length can take different drive link counts depending on the saw’s mount and sprocket.

If your bar etching is legible, the drive link count is stamped right there (the 55x in the example above). If not, lay the chain out and count the drive links by hand. Mark your starting link with a paint pen so you don’t lose your place.

Decoding a Stihl Chain Box

Stihl currently builds chain across the full range of pitch sizes above, and every box carries the same identification system. The short alphanumeric code, like 63 PM3 or 36 RS, packs the whole spec into a few characters:

Breakdown of the identification information printed on a Stihl chain box: pitch, gauge, chain code 26 RS, maintenance specs, and drive link count — A Stihl chain box carries the pitch, gauge, chain code, and drive link count.

Position	Meaning
First digit	Pitch code (see pitch table above).
Second digit	Gauge code (see gauge table above).
First letter	Cutter type: P = Picco (low-profile) • R = Rapid (standard height).
Second letter	Cutter shape: M = Micro (semi-chisel) • S = Super (full chisel) • D = Duro (carbide tip) • DS = Duro Special (carbide) • R = Rescue.
Trailing number/letter	Special features: 1 = triple-humped tie strap (PM chain) • 2 = triple-humped tie strap (RM chain) • 3 = single-humped drive link • F = full skip • H = semi skip (half skip).

Reading the Rest of the Box

The chain code is only part of what’s printed on that box. The rest of the panel tells you how to maintain the chain. Stihl even confirms the match on the chain itself:

On the Box	What It Tells You
Color square	Yellow = aggressive, full-performance chain. Green = reduced-kickback, safety-focused chain. It cuts a little slower, but it’s far more forgiving. The chain confirms the match: a yellow master link on the chain lines up with the yellow indicator on the box.
File size	The round file diameter for sharpening this chain, e.g., 4.8 mm / 3/16″. Using the wrong file size ruins the cutter profile.
Depth gauge setting	How far below the cutter’s top plate the depth gauge (raker) should sit, e.g., 0.65 mm / .025″.
Sharpening angle	The filing angle against the tooth, 30° on most Stihl chain.
Drive link count	The 68 in the long number printed on the box is the drive link count. Don’t get hung up on the long number itself. At the counter, this chain is identified as 26 RS 68: code plus drive link count.

Confirming it on the chain itself: on a chain coded 26, you’ll find the 2 (pitch code, .325″) etched on the upper left of the drive link and the 6 (gauge code, .063″) on the lower right. Bare chain, no box, no bar, you can still read exactly what it is.

The wear line is the finish line. Look at the top of each cutter, there’s an indicator line etched into it. Every sharpening removes cutter material, and when you’ve filed back far enough to reach that line, the chain is done. That’s not a suggestion; past the line there isn’t enough tooth left to cut safely. Time to buy a new chain.

Cutter Shape = Cutting Personality

The shape of the tooth changes how the chain behaves. A full-chisel Super cutter takes an aggressive, square-cornered bite. This is the fastest cutting, but it dulls quicker in dirty wood and demands more respect on kickback. A semi-chisel Micro cutter rounds that corner off which is a little slower, a lot more forgiving, and it holds an edge longer. The humped tie straps and drive links (the 1/2/3 codes) are low-kickback, safety-focused designs which is the difference the yellow and green box marking is telling you about.

Common Stihl Chain Codes at a Glance

Put the pitch digit and gauge digit together and the whole system snaps into focus:

Code	Pitch	Gauge	Where You’ll See It
71	1/4″P	.043″	Small top-handle and battery saws.
13	1/4″	.050″	Carving and specialty applications.
23	.325″	.050″	Mid-size farm and homeowner saws — e.g., 23 RM3 81.
26	.325″	.063″	Mid-size saws with .063″ bars — e.g., 26 RS full chisel.
61	3/8″P	.043″	Light battery and compact saws.
63	3/8″P	.050″	The classic consumer-saw combo — e.g., 63 PM3 55 on a 16″ bar.
33	3/8″	.050″	Full-size 3/8″ on .050″ bars.
35	3/8″	.058″	Full-size 3/8″ on .058″ bars.
36	3/8″	.063″	Professional saws — e.g., 36 RS full chisel.
46	.404″	.063″	Large professional and harvester saws.

Worked example: 63 PM3 55 = 3/8″P pitch (6) • .050″ gauge (3) • Picco Micro semi-chisel (PM) • single-humped low-kickback drive link (3) • 55 drive links. That’s the exact chain for the 16″ bar 3005 000 4813 shown earlier.

One more, off the box: 26 RS 68 = .325″ pitch (2) • .063″ gauge (6) • Rapid Super full chisel (RS) • 68 drive links. On the chain itself, the 2 is etched on the upper left of the drive link and the 6 on the lower right. The yellow master link matches the yellow square on the box.

The Tool That Does All of This For You

If you’d rather not eyeball rivets with a ruler, there’s a purpose-built answer: the Granberg Pitch-N-Gauge saw chain check tool (model G81), available through Rotary as part number 4248. It’s a flat card-style gauge that checks everything on this page in one pass just drop the chain into the pitch slots (.250 through .500), check the drive link and bar groove gauge, verify your file size, and confirm depth gauge settings and filing angles. One tool, every measurement, no guesswork.

Shop the Granberg Pitch-N-GaugeRotary part number 4248 • Granberg G81

No check tool handy? A basic digital caliper covers pitch and gauge measurement too:

Shop Digital Calipers on Amazon6″ digital caliper — reads inches & mm

Swapping Bars & Chains: Where People Get Burned

You typically have options when it comes to bar and chain combos on a given saw but every part of the system has to agree. The two rules:

Spec	Has To Match	What Goes Wrong
Pitch	The drive sprocket	Wrong pitch and the drive teeth won’t seat in the sprocket notches. This is where most swaps go sideways.
Gauge	The bar groove	Wrong gauge and the drive links won’t fit completely in the groove of the bar.

The classic scenario at the counter: somebody swapped a bar at some point, comes in for a new chain, and has no idea what’s actually on the saw. The assumption is they’re all the same. They’re not. And if you want to change pitch, say, moving a saw from 3/8″P to .325″, the bar and chain aren’t the whole job. You may also have to change the sprocket so the whole drivetrain agrees.

Spur vs. Rim Sprockets

Two sprocket styles drive that chain. A spur sprocket, a one-piece star, is standard on homeowner saws: simple, cheap, no fuss. A rim sprocket, a replaceable rim floating on a splined drum, is standard on professional saws: it self-aligns with the chain, wears more evenly, and swaps out in minutes when it’s done.

Rim sprockets also give you a tuning option: tooth count. A .325-7 rim (7 teeth) runs the chain a little slower but delivers more torque which is better for bigger wood and dirty cuts. A .325-8 (8 teeth) runs higher chain speed with less torque which is faster in clean, smaller wood. Same pitch, different personality.

Sprocket check, every chain swap: the drive teeth ride in the notches of that sprocket. Grooves worn into the sprocket mean it’s replacement time. Hang a new chain on a grooved sprocket and you’ll be back for another chain sooner than you’d like.

Chain Identification FAQ

How do I identify my chainsaw chain size?

Three measurements identify any chain: pitch (distance between three rivets divided by two), gauge (thickness of the drive link), and drive link count (how many it takes to go around the bar and sprocket). On a Stihl bar, all three are etched on the bar along with the bar’s part number.

What does the number stamped on the drive link mean?

Stihl etches the chain’s identity right on the drive link: the pitch code digit on the upper left, the gauge code digit on the lower right. Gauge codes: 1 = .043″, 3 = .050″, 5 = .058″, 6 = .063″, 0 = .080″ (harvester chain only). It’s the fastest way to identify a bare chain.

What happens if I run the wrong pitch?

Pitch controls how the drive teeth fit the notches of the drive sprocket. A wrong-pitch chain won’t mesh properly. It rides rough, wears both parts fast, and can jump or break. And if your sprocket has grooves worn into it, replace it before you hang a new chain on it.

Can I put a different gauge chain on my bar?

No. Gauge has to match the bar’s groove width exactly. Too thin wobbles and cuts crooked; too thick won’t seat in the groove.

What’s a chain “loop”?

Counter slang for a pre-cut, factory-assembled length of chain. Use the term all you like in the shop but order by part number or by pitch, gauge, and drive link count.

How do I know when my chain is worn out?

Look at the top of the cutters, there’s a wear indicator line etched into each one. Every sharpening files the cutter back, and once you’ve filed down to that line, the chain is done. Replace it; there’s not enough tooth left to cut safely past the line.

Can I put any bar on my saw as long as it mounts up?

Not quite. The chain’s pitch has to match your drive sprocket, and the chain’s gauge has to match the bar’s groove. If you change pitch, you may need to change the sprocket too, so the whole drivetrain agrees. This is the most common mix-up we see when people swap bars and later come in for a chain without knowing what’s on the saw.

Is there a tool that measures chain pitch and gauge for me?

Yes. The Granberg Pitch-N-Gauge check tool (Rotary part number 4248) is a flat gauge that checks pitch, drive link gauge, bar groove, file size, depth gauge settings, and filing angles in one tool. A digital caliper works too if you’d rather measure manually.

What’s the difference between a spur sprocket and a rim sprocket?

A spur sprocket is a one-piece star, standard on homeowner saws. A rim sprocket is a replaceable rim on a splined drum, standard on professional saws. It self-aligns and is cheap and quick to replace. On rims, tooth count is a tuning choice: a .325-7 runs a little slower with more torque, while a .325-8 runs higher chain speed with less torque.

Still Not Sure Which Chain You Need?

Bring the bar or the old chain to your local servicing dealer and they’ll match it in about thirty seconds. Or work through the charts above with a caliper in hand. Either way: pitch, gauge, drive links. Those three numbers are the whole story.