The ANSI roller chain size chart is one of the most referenced documents in industrial maintenance — yet it is also one of the most frequently misapplied. The chart lists the dimensional specifications that define each ANSI chain number, from the smallest (ANSI 25 at 6.35 mm pitch) to the largest commonly used sizes (ANSI 240 and above for heavy industrial applications). Knowing where to find this chart, how to read it correctly, and what the numbers mean in practice is the foundation of correct chain identification and specification. This article explains the complete ANSI chain size chart and where to obtain authoritative specification data.
The Authoritative Source: ANSI B29.1
The definitive source of ANSI roller chain specifications is the standard document ANSI B29.1, “Precision Power Transmission Roller Chains, Attachments, and Sprockets,” published and maintained by the American National Standards Institute (ANSI) and the American Society of Mechanical Engineers (ASME). This standard defines all dimensional requirements, breaking load requirements, and sprocket geometry for the complete ANSI chain family.
The ANSI B29.1 standard document is available for purchase from the ANSI webstore (webstore.ansi.org) and the ASME publication store. The current edition as of 2026 is ANSI/ASME B29.1-2011 (most recently reaffirmed in 2016). This is the document referenced in OEM equipment specifications, engineering standards, and quality certification documentation. For professional procurement and engineering use, referencing the current edition of B29.1 is the only fully authoritative approach.
ANSI Roller Chain Specification Table: Standard Series
| ANSI No. | Pitch (mm) | Pitch (in) | Roller Dia. (mm) | Inner Width (mm) | Pin Dia. (mm) | Plate Thick. (mm) | Min. Break Load (kN) |
|---|---|---|---|---|---|---|---|
| 25 | 6.350 | 1/4 | 3.30 | 3.18 | 2.31 | 0.76 | 3.1 |
| 35 | 9.525 | 3/8 | 5.08 | 4.78 | 3.59 | 1.27 | 8.0 |
| 40 | 12.700 | 1/2 | 7.92 | 7.85 | 3.97 | 1.50 | 14.1 |
| 50 | 15.875 | 5/8 | 10.16 | 9.53 | 5.09 | 2.00 | 21.8 |
| 60 | 19.050 | 3/4 | 11.91 | 12.57 | 5.94 | 2.40 | 31.3 |
| 80 | 25.400 | 1 | 15.88 | 15.75 | 7.94 | 3.20 | 55.6 |
| 100 | 31.750 | 1-1/4 | 19.05 | 18.90 | 9.53 | 3.96 | 87.0 |
| 120 | 38.100 | 1-1/2 | 22.23 | 25.22 | 11.11 | 4.80 | 125.0 |
| 140 | 44.450 | 1-3/4 | 25.40 | 25.22 | 12.70 | 5.60 | 170.0 |
| 160 | 50.800 | 2 | 28.58 | 31.55 | 14.29 | 6.40 | 222.0 |
ANSI Heavy Series Specifications
| ANSI No. | Pitch (mm) | Plate Thick. Std (mm) | Plate Thick. H (mm) | Break Load Std (kN) | Break Load H (kN) | Increase |
|---|---|---|---|---|---|---|
| 40H | 12.700 | 1.50 | 2.00 | 14.1 | 18.2 | +29% |
| 50H | 15.875 | 2.00 | 2.60 | 21.8 | 27.1 | +24% |
| 60H | 19.050 | 2.40 | 3.20 | 31.3 | 42.3 | +35% |
| 80H | 25.400 | 3.20 | 4.00 | 55.6 | 74.7 | +34% |
| 100H | 31.750 | 3.96 | 4.80 | 87.0 | 117.0 | +34% |
| 120H | 38.100 | 4.80 | 5.60 | 125.0 | 167.0 | +34% |
How to Read and Apply the Size Chart
Decoding the ANSI Chain Number
The ANSI chain number encodes the pitch directly. The first one or two digits represent the pitch in eighths of an inch: ANSI 40 = 4/8 inch = 0.5 inch = 12.70 mm; ANSI 60 = 6/8 inch = 0.75 inch = 19.05 mm; ANSI 80 = 8/8 inch = 1.0 inch = 25.40 mm. The suffix digit carries additional information: a zero suffix (40, 60, 80) indicates standard series with normal rollers; a suffix of H (40H, 60H) indicates heavy series; a suffix of 1 (41, 61) indicates rollerless chain; a suffix of 5 (35, 55) indicates light series with smaller rollers and reduced breaking load.
Multi-Strand Designation
Duplex and triplex chain are designated with a strand count suffix after the chain number: ANSI 60-2 is ANSI No. 60 pitch in duplex (two-strand) configuration; ANSI 80-3 is ANSI No. 80 pitch in triplex (three-strand) configuration. Working load for multi-strand chain uses strand efficiency factors: duplex approximately 1.74x simplex; triplex approximately 2.49x simplex — not simple multiples of the strand count due to load distribution imperfection across strands.
Other Sources for ANSI Chain Specifications
Beyond the ANSI B29.1 standard document itself, reliable ANSI roller chain specification data is available from several sources:
Manufacturer Technical Catalogues
Major chain manufacturers (Tsubaki, Renold, Rexnord) publish technical catalogues with complete dimensional tables, power rating charts, and engineering data. These are available from manufacturer websites and from their Australian distributors.
Specialist Importer Data Sheets
EverPower Roller Chains Australia can provide dimensional data sheets for all ANSI chain sizes in our product range. Contact our Sydney team to request specification sheets for your chain sizes of interest.
Engineering Reference Books
Standard mechanical engineering references including Shigley’s Mechanical Engineering Design and Machinery’s Handbook include ANSI chain specification tables and power rating methodology.
Standards Organisations
Standards Australia (standards.org.au) and the ANSI webstore (webstore.ansi.org) provide access to the current edition of ANSI B29.1 for purchase. ISO 606 is available from ISO (iso.org) for the equivalent European/international standard.
Matching Measurement to Chart: A Practical Worked Example
You have a worn chain on a piece of equipment with no documentation. You measure across 10 links (pin centre to pin centre) and get 195.5 mm. Dividing by 10 gives 19.55 mm per pitch. The closest standard ANSI pitch is 19.05 mm (ANSI 60). The elongation is (19.55 – 19.05) / 19.05 x 100 = 2.6 percent — approaching the 3 percent replacement threshold. You then measure roller diameter: 11.9 mm, which matches ANSI 60 (11.91 mm). You measure inner width: 12.5 mm, which matches ANSI 60 (12.57 mm). Conclusion: ANSI No. 60 simplex, 2.6 percent elongated. Replacement chain required: ANSI 60-1 (simplex). This three-measurement identification process works for any ANSI roller chain without relying on markings.
EverPower Roller Chains Australia can assist with chain identification from field measurements and provide dimensional specification data for any ANSI or ISO chain size in our range. Contact our Sydney team with your measurements and we will identify the correct chain specification and provide a quotation for replacement chain.
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