How to Choose a Chainsaw Chain: Pitch, Gauge, Drive Links

A replacement chain has to match your bar on three numbers — pitch, gauge and drive-link count — and the bar length tells you which bar that is. Bar length alone is not enough: two 16” bars can take chains with different pitch, gauge or drive-link counts. Get all three numbers from the bar, the old chain or the saw’s manual, and order the chain that matches every one.

Pitch

Pitch is the distance between any three consecutive rivets, divided by two. The drive sprocket and the bar’s nose sprocket must have the same pitch as the chain. Oregon lists six chain pitches: 1/4”, .325” Low Profile, 3/8” Low Profile, .325”, 3/8” and .404” (Oregon manual, p. 14).

Pitch is half the distance across three consecutive rivets. A ruler can’t tell 3/8” from 3/8” Low Profile.

3/8” Low Profile is not 3/8”. Oregon treats them as separate pitches, and a chain of one will not substitute for the other. The same goes for .325” Low Profile and .325”. If your bar or manual says “3/8 LP”, order exactly that.

Low Profile refers to the chain’s lower cutters, not to the drive-link thickness. A 3/8” LP chain comes in more than one gauge — Oregon’s 90-series is 3/8” LP in .043”, its 91-series is 3/8” LP in .050” (Oregon manual, p. 48) — so you still need the gauge.

Gauge

Gauge is the thickness of the drive link where it fits into the bar groove, and it must match the groove. The standard gauges are .043” (1.1 mm), .050” (1.3 mm), .058” (1.5 mm) and .063” (1.6 mm) (Oregon manual, p. 14).

Gauge is the drive-link thickness, and it must equal the width of the bar groove.

Can I put a .043” chain on a .050” bar?

No. Oregon’s rule is that the gauge of the chain and the gauge of the bar must match (Oregon). It goes wrong in both directions:

• A .050” chain on a .043” bar has drive links thicker than the groove, so it won’t seat in the bar.
• A .043” chain on a .050” bar fits into the groove, so the mistake isn’t obvious when you mount it. But the thinner drive links have room to lean in the wider groove. Oregon’s troubleshooting guide lists a chain thinner than its bar (its example is a .063” chain in a .080” bar) as a cause of one rail wearing thin, crooked cuts and the bar binding in the cut (Oregon manual, p. 94).

Both gauges are sold in 3/8” Low Profile (Oregon’s 90 and 91 series, table below), so check the gauge even when pitch and length match. If your saw came with a .043” bar and you want a .050” chain, you need a .050” bar as well, and the reverse.

Drive-link count

The drive links are the tabs on the underside of the chain that ride in the bar groove and engage the sprocket. Chain length is given as the number of drive links, and it has to match the bar you are using (Oregon FAQ). The count depends on the bar, not just its length, so don’t assume a count from the bar size — read it or count it.

Count the tabs underneath, not the cutters, all the way around to your start mark.

Where to find the numbers

1. The bar tail. Most bars carry pitch, gauge and often the drive-link count near the mounting end. STIHL stamps the required drive-link count into the tail of every bar (STIHL Sharp Advice, pp. 6–7). Don’t confuse the bar’s own part number or mount code with chain specs — see bar mount codes.

   

   An example stamp: pitch, gauge and drive-link count. The mount code belongs to the saw fit, not the chain. Wording and layout vary by maker.

2. The drive links of the old chain. Oregon stamps a number on its drive links that identifies pitch and gauge, and recommends ordering by it rather than by measuring a worn chain (Oregon FAQ). STIHL stamps the pitch on each depth gauge and the last digit of the gauge in millimeters on each drive link (STIHL Sharp Advice, pp. 6–7).

3. The saw’s manual, which lists the bar and chain it was sold with.

4. The old chain’s package, if you still have it.

Oregon’s drive-link numbers (manual, p. 48):

Number on drive link	Pitch	Gauge
25	1/4”	.050”
80	.325” Low Profile	.043”
90	3/8” Low Profile	.043”
91	3/8” Low Profile	.050”
20, 95	.325”	.050”
21	.325”	.058”
22	.325”	.063”
72	3/8”	.050”
73	3/8”	.058”
75	3/8”	.063”
26, 58	.404”	.058”
27, 59, 68	.404”	.063”

These numbers are Oregon’s own. Other brands use different codes, so look them up in that maker’s chart.

Measuring when the markings are gone

Count the drive links. Lay the chain flat, mark one drive link with tape or a paint pen, and count every drive link around the loop until you are back at the mark. Count only the tabs underneath — not the cutters on top. If the chain is broken, lay the pieces end to end and count them all, as long as no section is missing.

Measure pitch. Measure center-to-center from the first to the third of three consecutive rivets and halve it:

Span across 3 rivets	Pitch
1/2” (12.7 mm)	1/4”
0.65” (16.5 mm)	.325”
3/4” (19.05 mm)	3/8”
0.808” (20.5 mm)	.404”

A worn chain won’t measure exactly; pick the nearest value. A ruler can’t separate 3/8” from 3/8” Low Profile (or .325” from .325” LP), because they share the same rivet spacing — use the bar stamp, the drive-link number or the manual for that.

Measure gauge. Use calipers on the flat part of a drive link and pick the nearest standard gauge. Oregon notes that normal wear makes gauge hard to measure accurately on a worn chain, which is why the drive-link stamp is the better guide (Oregon FAQ).

Bar length. The length a bar is sold by is its “called length”: the distance from the front of the saw to the tip of the bar, which is shorter than the bar’s overall length (Oregon manual, p. 49).

Before you order

• Match pitch, gauge and drive-link count exactly. A count one link off is a different chain.
• If two sources disagree (say, you measured 3/8” but the bar says .325”), recheck before ordering.
• The bar on a used saw may not be the original. Read the bar that is actually fitted, not just the saw model.
• Use a low-kickback chain; see choosing the replacement.

Our specs page compares our chains by bar size, pitch, gauge and drive-link count, the parts finder lists them by saw model, and the chain cross-reference turns an OEM or Oregon part number into its size.

Sources

• Oregon — Safety & Maintenance Manual (PDF): saw chain terms (p. 14), drive-link number identification (p. 48), how to order replacement chain (p. 49)
• Oregon — FAQ: pitch, gauge and chain length
• STIHL USA — Sharp Advice for chain saw owners (PDF): design of STIHL saw chain (pp. 6–7)

Checked against these sources on October 1, 2026.