Roller Chain Size Chart
Look up the pitch, roller diameter and inner width of ANSI and ISO roller chain, decode a chain number, or identify a chain you measured.
This roller chain size chart is a free, browser-based reference that lists the pitch, roller diameter and inner width of 28 roller chain sizes, covering ANSI and ISO B-series chain. It can also match a chain you have measured against the closest sizes, which helps when you need a drive chain or industrial chain size chart without searching through several maker catalogs.
It also decodes a chain number such as 60H-2 into pitch, roller, width and strands. Everything runs in your browser, and there is no account or sign-up. You can browse the full table or enter your own measurements and see how close each size is, with deviations shown in percent and millimetres.
How to use the Roller chain size chart
- Under “What do you want to do?”, choose Decode a chain number, Identify a chain by measuring, or Show the size chart (all 28 sizes, or one chain family).
- To decode, type a chain number such as 40-2, 60H or 08B-1 into the chain number box.
- Read the result as you type. It updates with every change, so you do not need a separate button to calculate.
- To identify a chain, enter the length you measured from pin centre to pin centre, the number of pitches it spans, and optionally the roller diameter and inner width.
- Set the unit menu beside each quantity to inches or millimetres. You can mix units, because the tool converts them before it calculates.
- Open “How it was calculated” under the result to check the formula, the values substituted and the answer with units.
- Click a preset button above the form to load a typical case: No. 40, 60H-2 heavy duplex, 08B-1, or a 6.1 in measurement over 12 pitches.
- Read the deviation column in identify mode: the smaller the percentage, the closer the match. A used chain reads a little long, so the nearest size is usually the right one.
Click “Reset” to restore the starting example. Copy result, Copy link and Print / save as PDF under the result keep a record of the size you found.
Roller chain size guide: how do I read the chain number?
A roller chain size number encodes the pitch, the chain type and, in some cases, the series or number of strands. In ANSI numbers, the digits before the last one give the pitch in eighths of an inch, and the last digit gives the chain type.
For example, No. 40 is 4/8 in, or 0.500 in (12.7 mm). No. 60 is 0.750 in, and No. 120 is 1.500 in. The last digit tells you the type: 0 is standard roller chain, 1 is narrow light-duty chain (No. 41), and 5 is rollerless bushing chain (No. 25 and 35). For chains 25 and 35, the diameter in the table is the bushing outside diameter, not a roller diameter.
Two suffixes add detail. “H” marks the heavy series (60H and up), which has the same pitch and roller as the standard chain but thicker plates. “-2” and “-3” mean two or three strands, with the same pitch, roller and inner width per strand.
ISO B-series numbers work differently. From 06B up, the first two digits give the pitch in sixteenths of an inch, so 08B is 8/16 in, or 12.7 mm, and 16B is 25.4 mm. ISO A-series names are ANSI chain with metric numbers: 08A is No. 40, 10A is No. 50, 12A is No. 60, and 16A is No. 80.
How do I measure a chain to identify its size?
Pull the chain straight and measure from pin centre to pin centre across several pitches, for example 12. Divide that length by the number of pitches to get the pitch of one link. Then compare that value with the nominal pitch of the candidate size.
A used chain reads long because its joints wear. Up to about 3 % over nominal still identifies the size. Beyond 3 %, the chain is normally due for replacement (a distributor’s guideline, Texas Belting).
As a worked example, 6.1 in measured over 12 pitches gives 0.508 in per pitch. That is closest to ANSI 40, at +1.67 % pitch deviation.
Sources
Checked October 2026 (dimensions only; inch values as printed, mm converted at 25.4):
- ANSI chain: Peer Chain single-strand roller chain size chart (main table; its No. 50 roller and width columns are swapped and were corrected from the other sources), U.S. Tsubaki catalog, Tsubaki Europe, Texas Belting (also the measuring method)
- ISO 606 B-series: MM-Intercom roller chain series B data sheet, BEP stainless roller chain, U.S. Tsubaki catalog p. B-21
For estimation; verify critical designs against the applicable standard.
Worked examples
| Input | Result |
|---|---|
| chain number 40-2 | ANSI 40, 2 strands: pitch 0.5 in (12.7 mm), roller 7.92 mm, inner width 7.92 mm |
| chain number 60H | ANSI 60 heavy series: pitch 0.75 in (19.05 mm), roller 11.91 mm, inner width 12.7 mm |
| chain number 08B-1 | ISO 08B: pitch 0.5 in (12.7 mm), roller 8.51 mm, inner width 7.75 mm |
| 6.1 in over 12 pitch(es), roller 0.31 in, inner width 0.31 in | closest: ANSI 40 (pitch +1.67 %) |
| 12.7 mm over 1 pitch(es), roller 8.5 mm, inner width 7.75 mm | closest: ISO 08B (pitch 0.00 %) |
| table: all | 28 sizes listed |
Calculated by the tool above with these values.
Frequently asked questions
Can I use the results in commercial projects or client reports?
Yes. You can use the results in commercial work, including quotes, design notes, reports and client projects, without attribution. The result itself says it is for estimation, so verify critical designs against the applicable standard. The tool does not certify compliance with any code.
Is the calculator free, and is anything I type uploaded?
Yes, the calculator is free and needs no account or sign-up. Everything is calculated in your browser, and nothing you type is uploaded.
Can I print or share a calculation?
Yes. “Print / save as PDF” produces a one-page record with the inputs, results, calculation steps and date. “Copy link” copies the page address, which stores every input in the ?s= part of the URL, so the same calculation reopens later or can be sent to a colleague. “Copy result” copies the result lines with a link.
Why can’t pitch alone identify a chain?
No. 40, No. 41 and 08B all have a 12.7 mm pitch. Roller diameter and inner width separate them: No. 40 has a 7.92 mm roller and 7.92 mm inner width, No. 41 has a 7.77 mm roller and 6.35 mm inner width, and 08B has an 8.51 mm roller and 7.75 mm inner width. Because 08B is not interchangeable with No. 40, measure the roller and inner width too.
Which sizes does the chart include?
The chart lists 28 sizes in total, covering ANSI roller chain and ISO B-series chain. It does not include the other ISO A-series numbers, such as 20A or 24A. For heavy H chain, the tool does not give pin diameters, because the sources do not state them.
Why might a value differ from another catalog?
Inch values for ANSI chain are as printed by makers, and millimetres are converted at 25.4 mm per inch. Pin diameters are given only where the sources list them, and maker values can differ by about 0.02 mm. For a purchase or a critical design, check the figure against your supplier’s catalog.
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