ANSI Roller Chain

ANSI roller chain is precision drive chain built to the ASME/ANSI B29.1 standard, with the chain number encoding pitch in eighths of an inch. Texas Belting stocks 1,000+ Lynx industrial chain products in Houston: #25 through #240 in single, double, and triple strand, plus stainless, connecting links, and leaf chain.

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On this page: Size chart · Measure · 1/2 in family · Interchange · Wear limits · Materials · Quantity · Houston · Mistakes · FAQ

ANSI roller chain size chart (#25 to #240)

Roller chain numbers encode the size: left digits = pitch in eighths of an inch (#40 = 4/8 = 1/2 in; #120 = 12/8 = 1-1/2 in), and the last digit is the construction - 0 standard roller chain, 1 narrow light-duty, 5 rollerless bushing chain. The chart gives ANSI B29.1 dimensions, each size linked to stock.

*Bushing OD (#25 and #35 are rollerless bushing chains). Roller width = width between inner plates. Standard-series ANSI minimums (last digit 0) follow the B29.1 formula (12,500 × pitch squared); light-duty #41 is rated separately at 1,500 lb. Averages are typical published manufacturer ratings and vary by brand. Links per 10 ft = 120 in / pitch (#140 rounds to a whole pitch count).

Multi-strand chain (40-2 duplex, 60-3 triplex) does not double capacity: standard rating factors are 1.7 for two strands, 2.5 for three. Heavy series (60H and up) keeps the pitch and roller with thicker plates - see XD extreme duty chain for drives that keep breaking chain.

How do I measure roller chain to find its size?

Identify roller chain with three measurements: pitch, roller diameter, and inner width between the link plates. A single pitch is hard to read - and worn chain measures long - so pull the chain taut, measure pin center to pin center across 12 pitches, divide by 12, and match below. Inner width separates the 1/2 in family; above 1-1/2 in pitch, use the master chart.

#40 vs #41 vs 420 vs 425: the 1/2 in pitch family

Four common chains share the 1/2 in pitch and are not interchangeable: #40 is the full-width industrial standard, #41 is narrower and lighter with lower plates, and 420/425 are powersports chains with taller plates and heavier pins. All four engage the same tooth spacing - but a sprocket cut for #40's 0.312 in width is too thick for the 0.250 in wide #41 and 420.

Many small-equipment sprockets are cut to a narrower 40/41/420 compromise tooth; for industrial drives, spec #40 unless the machine was built around #41's lighter rating.

Roller chain interchange: brands and standards

ANSI chain numbers are a standard, not a brand: Tsubaki RS40, Diamond 40, and Lynx 40 all build to the same ASME B29.1 dimensions, so a #40 from any manufacturer replaces the others. ISO 606 A-series numbers (08A = #40, 10A = #50, 12A = #60, 16A = #80) are the same chains under metric designations. British Standard B-series shares the pitch only - 08B runs an 8.51 mm roller against #40's 7.92 mm - so it is not a drop-in on ANSI sprockets. A #50 connecting link likewise fits any brand's standard-series #50 of the same strand count. We stock British Standard metric chain too.

Interchange references are based on manufacturer-published equivalents. Verify dimensions before ordering.

When should roller chain be replaced?

Replace roller chain at 3% elongation for most drives - past that, the chain no longer seats on the sprocket pitch line and destroys teeth quickly. Use roughly 1.5% for fixed-center drives, multi-strand chain, or smooth-indexing drives, and 200/N percent when the large sprocket has 68 or more teeth. Chain does not actually stretch: pins and bushings wear, lengthening every pitch. Measure 12 pitches under tension and compare:

Carbon steel vs stainless vs nickel-plated chain

Standard carbon steel chain carries the full published rating and costs the least. Nickel-plated chain adds mild corrosion protection for humid or occasionally washed-down areas. 304 stainless resists washdown chemicals and food-plant sanitation but gives up strength: typical published ratings run roughly half to two-thirds of carbon.

Because of the derate, a drive working a carbon #50 hard may need a stainless #60. Dimensions are identical within a size, so sprockets change only if the size does.

How much chain do I need?

Boxed chain comes in 10 ft lengths, so links per box = 120 in / pitch: 240 links of #40, 192 of #50, 160 of #60, 120 of #80. For a new run, size the chain from the center distance and tooth counts:

Chain length formula (in pitches): L = 2C + (N + n)/2 + (N - n)² / (39.5 × C), where C = center distance in pitches, N and n = large and small tooth counts.

Worked example: #60 chain (0.750 in pitch), 17T and 40T sprockets, 30 in centers. C = 30 / 0.750 = 40 pitches, so L = 80 + 28.5 + (23 × 23) / (39.5 × 40) = 108.8. Round up to an even 110 pitches = 82.5 in; one 10 ft box (160 pitches) covers it.

An even pitch count closes with a standard connecting link; an odd count needs an offset (half) link, generally the weakest point in a chain.

Roller chain supplier in Houston, TX

Texas Belting & Supply stocks Lynx roller chain and links at our Houston, TX warehouse - most stocked sizes ship same day. We serve plants, gins, mills, and OEMs across the Texas Gulf Coast and ship nationwide. Quotes typically turn around within one business day; call (888) 203-2358 to confirm availability.

Common roller chain selection mistakes

• Ordering "1/2 inch chain" without checking width. Four chains share the pitch (#40, #41, 420, 425); measure inner width too.
• Sizing up because a worn chain measures long. A chain reading 2-3% over nominal is that size, worn - not the next size up.
• Running new chain on worn sprockets. Hooked teeth chew up new chain fast; replace as a set.
• Mixing ANSI and British Standard. 08B is not a #40: same pitch, different roller diameter and width. Match the standard to the sprockets.
• Assuming stainless carries carbon ratings. Typical published stainless ratings run roughly half to two-thirds of carbon - re-check the load and upsize if needed.

When to call instead

Call us when the job involves:

• Attachment chain (A-1, K-1) for conveyors
• Agricultural chain (CA550, CA557 and similar) for harvesters and gins
• BL series leaf chain sizing for forklift masts and hoists
• Drives that keep breaking chain - candidates for heavy series or XD extreme duty
• Corrosive or high-temperature environments needing a material call
• Cross-referencing an obsolete or unbranded chain from a sample

Call (888) 203-2358 or send us what you have.

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Last updated: July 2026