Chain pitch is the distance between the centers of two consecutive pins in a roller chain, and it is the single spec that has to match between a chain and a sprocket before anything else about the drive matters. Get it wrong and the chain won't seat on the tooth profile, no matter how close the other dimensions are. This guide covers what pitch is, how to measure it accurately, when wear means it's time to replace the chain, and a quick ANSI reference chart for the sizes we stock.
What Is Chain Pitch?
Chain pitch is the distance between the centers of two consecutive pins. It determines whether a chain will mesh with a given sprocket — nothing else about the chain matters if the pitch is wrong.
Why Chain Pitch Matters
Sprocket teeth are cut to a specific pitch, so a mismatched chain simply won't seat correctly — it will ride up on the teeth, skip under load, or wear both parts out within weeks. Pitch also tracks with load capacity: under ANSI B29.1, a single-strand #40 chain (1/2" pitch) carries a rated working load of 810 lb, while a #60 chain (3/4" pitch) is rated to 1,980 lb — more than double, for a pitch increase of just 1/4". Smaller-pitch chains also run quieter at high RPM, which is why conveyor and packaging equipment tend to favor #25 and #35 over the larger sizes used in slow, high-torque drives like agricultural gearboxes.
Pitch is also embedded in the chain's own name — that connection is worth its own section further down.
How to Measure Chain Pitch
Lay the chain flat, fully extended, no slack.
Find three consecutive pin centers. A single link end-to-end won't give you pitch — you need pin center to pin center.
Measure across 10 pitches, then divide by 10. A caliper reading is accurate to roughly ±0.01". On a single 1/2" pitch, that's a 2% error. Spread across 10 pitches (5"), the same ±0.01" reading error becomes 0.2% — and it also averages out the small, normal manufacturing tolerance in each individual link.
Compare the result to the chart below to identify the standard designation.
If your measured pitch falls between two standard sizes, check for wear before assuming you've found a nonstandard chain — a stretched #40 will measure larger than 0.500" without being anything other than a worn #40. The next section covers exactly how much stretch is normal.
When to Replace: Chain Wear and Elongation
The most common reason a field measurement doesn't match a standard pitch isn't a bad caliper reading — it's wear. As a chain runs, the pins and bushings wear against each other and the effective pitch grows; the industry calls this elongation. A U.S. patent filing on roller chain wear gauges documents the two thresholds used across the industry: once elongation passes 1.5% on a fixed-center-distance or precision drive, or 3% on a general industrial drive with adjustable centers, the chain should be replaced — beyond that point it rides higher on the sprocket teeth and accelerates wear on both parts.
Rather than recalculating percentages by hand every time, most shops keep a chain wear gauge on hand: it hooks over a span of chain and gives a direct pass/fail reading against the 1.5% and 3% marks, no math required.
Chain Pitch Chart: Common ANSI Sizes at a Glance
Covers the ANSI range we stock in in-stock roller chain (#25–#160). For the full spec on each size — roller diameter, pin diameter, plate thickness — see the Roller Chain Size Chart.
ANSI No. | Pitch |
|---|---|
#25 | 1/4" |
#35 | 3/8" |
#40 | 1/2" |
#41 | 1/2" (lightweight) |
#50 | 5/8" |
#60 | 3/4" |
#80 | 1" |
#100 | 1-1/4" |
#120 | 1-1/2" |
#140 | 1-3/4" |
#160 | 2" |
Working in metric? ISO 606 chain uses the same pitch values under different names — ISO 08B is 12.7mm (1/2", same as ANSI #40) and ISO 12B is 19.05mm (3/4", same as ANSI #60). Matching pitch doesn't guarantee a drop-in sprocket swap, though: 08B's roller diameter (0.335") is slightly larger than #40's (0.312"), and the same kind of gap shows up between 12B and #60. Confirm roller diameter and width alongside pitch before cross-referencing between standards.
Chain Pitch vs. Chain Number
Under ANSI B29.1, the digits before the last one in a chain number give the pitch in eighths of an inch. A #40 chain is 4/8" = 1/2" pitch; a #60 chain is 6/8" = 3/4" pitch. This lets you estimate pitch from the stamped number alone, though a worn or corroded stamp is common enough that confirming with a caliper before ordering replacement parts is still worth the two minutes. It's also worth checking chain pitch against your sprocket and application needs in our Industrial Chains and Sprockets overview if you're specifying a full drive from scratch.
FAQ
What is chain pitch measured in?
Inches for ANSI standard chain, millimeters for ISO/metric chain.
How much can a chain stretch before it needs replacing?
1.5% elongation on fixed-center or precision drives, 3% on general industrial drives with adjustable centers. A wear gauge gives a direct pass/fail reading against both limits without any calculation.
What happens if I run the wrong-pitch chain on a sprocket?
It won't seat on the tooth profile correctly. Depending on how far off the pitch is, you'll see the chain ride up and skip under load, abnormal noise, or rapid wear on both the chain and the sprocket teeth within a short run time. It should never be forced onto a mismatched sprocket even if it appears to fit loosely.
What's the difference between pitch and chain width?
Pitch is the spacing between pin centers along the chain's length. Width is the distance between the inner link plates, which has to match the sprocket's tooth width separately from pitch. A chain spec isn't complete without both numbers.
Pitch values and elongation limits shown conform to ANSI B29.1 and standard industry maintenance practice. Confirm exact figures against your chain manufacturer's spec sheet before ordering replacement chain or making a run/replace decision.
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