Chain Pitch Converter
Look up roller chain pitch, width, and pin diameter by chain number in inches and millimeters.
Complete specs for all standard ANSI roller chain sizes.
Select a chain number — see pitch and specifications.
Roller chain is identified by ANSI chain number.
Chain numbering system:
- First digit(s) = pitch in 1/8 inch increments
- Last digit: 0 = standard, 1 = lightweight, 5 = bushing
Example: Chain #40 = 4/8 inch = 0.5 inch pitch
Common chain sizes:
| Chain # | Pitch (in) | Pitch (mm) | Roller Width (in) | Tensile (lbs) |
|---|---|---|---|---|
| #25 | 0.250 | 6.35 | 0.125 | 780 |
| #35 | 0.375 | 9.525 | 0.188 | 1,760 |
| #40 | 0.500 | 12.70 | 0.312 | 3,125 |
| #41 | 0.500 | 12.70 | 0.250 | 2,000 |
| #50 | 0.625 | 15.875 | 0.375 | 4,880 |
| #60 | 0.750 | 19.05 | 0.500 | 7,030 |
| #80 | 1.000 | 25.40 | 0.625 | 12,500 |
| #100 | 1.250 | 31.75 | 0.750 | 19,500 |
| #120 | 1.500 | 38.10 | 1.000 | 28,000 |
Double-strand chains (e.g., #40-2) have roughly 1.7x the tensile strength.
Pitch is the single most important number when matching a chain to its sprockets, because the teeth have to line up exactly with the links. A chain and sprocket of different pitch won’t mesh, no matter how close the sizes look, which is why replacement parts are specified by pitch first.
Bicycle chains are a special case worth knowing: almost all modern bikes use a 1/2-inch pitch, so what separates a 7-speed chain from a 12-speed one isn’t pitch at all, it’s width. More sprockets packed into the same space means narrower chains and tighter spacing. Industrial and motorcycle roller chains, by contrast, come in the ANSI pitches above, where both the pitch and the roller size change between standards. One practical tip: a chain “stretches” as it wears (the pivots wear, not the steel), so a worn chain measures slightly longer than its nominal pitch and should be replaced before it chews up the sprockets.
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This converter runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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