ANSI #40 roller chain has a 0.500 in (12.70 mm) pitch, a 0.312 in maximum roller diameter, and a 3,970 lb minimum tensile strength, and is the smallest of the three sizes commonly compared for fractional-horsepower drives per ASME B29.1-2011 [S2][S3].
ANSI #60 steps the pitch up to 0.750 in (19.05 mm) with a 0.469 in roller and a 9,270 lb minimum tensile strength, while ANSI #80 reaches 1.000 in (25.40 mm) pitch, a 0.625 in roller, and a 16,540 lb minimum tensile strength, more than quadrupling the load capacity of #40 in the same single-strand family [S2][S3]. Chain number digits ahead of the suffix encode pitch in eighths of an inch, so 40, 60, and 80 translate directly to 5/8 in, 6/8 in (3/4 in), and 8/8 in (1 in) nominal pitches [S2][S7].
Pitch, roller, and pin dimensions across #40, #60, and #80
ASME B29.1-2011 pins the nominal pitch for the three sizes at 0.500 in, 0.750 in, and 1.000 in (12.70, 19.05, and 25.40 mm), a 50% step between each size that also drives the rest of the geometry [S2][S3]. Maximum roller diameter scales with pitch, going 0.312 in for #40, 0.469 in for #60, and 0.625 in for #80, so a 0.312 in sprocket tooth gap will not accept an #80 chain regardless of how the rest of the drive is sized [S3].
Pin diameter follows the same monotonic increase: 0.156 in for #40, 0.234 in for #60, and 0.312 in for #80, which is the dimension that controls fatigue life because pins are the most highly stressed component in the link [S3]. Width between inner plates tracks from 0.312 in (#40) to 0.500 in (#60) to 0.625 in (#80), and link-plate thickness rises from 0.058 in to 0.093 in to 0.125 in across the same three sizes [S3]. On a per-foot basis, weight climbs from 0.42 lb/ft (#40) to 0.97 lb/ft (#60) to 1.71 lb/ft (#80), reflecting the larger cross-section in steel rather than any change in material grade [S3].
Tensile strength and working-load ratio
Single-strand minimum tensile strength per ASME B29.1-2011 is 3,970 lb for #40, 9,270 lb for #60, and 16,540 lb for #80, so a move from #40 to #80 multiplies the chain's static load capacity by roughly 4.2x without changing the strand count [S2][S3]. For reference, SY-chain metric data lists #40 average tensile at 19.10 kN, #60 at 43.10 kN, and #80 at 78.50 kN, all within a few percent of the ANSI figures once units are reconciled [S5].
Working load is typically set at 10–15% of minimum tensile for moderate-speed drives with good lubrication, which puts continuous service loads near 400–600 lb for #40, 900–1,400 lb for #60, and 1,600–2,500 lb for #80 in a single strand [S2]. Pin rivet stock is 0.156 in, 0.234 in, and 0.312 in respectively, so the fatigue rating of the chain is governed by pin bending and pin-bush bearing stress rather than by the plate steel itself [S3]. When duty cycles exceed the working-load envelope, the standard move is to step from single-strand to duplex (for example #60-2) on the same 0.750 in pitch rather than jumping to a different chain number, because duplex triples share the same sprocket tooth form as single-strand #60 [S2][S6].
Pitch-decoding rules and common sizing traps
The first one or two digits of an ANSI chain number indicate pitch in eighths of an inch, so #40 is 4/8 in, #60 is 6/8 in, and #80 is 8/8 in; the trailing 0 marks a standard roller chain, a 1 suffix (as in #41) marks a lightweight riveted-pin chain that shares #40's pitch but is not dimensionally interchangeable, and an H suffix (60H, 80H) marks a heavy series with the same pitch and roller as the standard chain but thicker link plates [S2][S7]. For dual-strand drives, a hyphenated suffix such as 60-2 or 80-2 indicates duplex, and a -3 suffix indicates triplex, all on the same 0.750 in or 1.000 in pitch and matched to a wider sprocket [S2][S4].
The most common trap is matching pitch only: #40, #41, and metric 08B all share a 0.500 in (12.70 mm) pitch, but their roller, width, and pin dimensions differ, and none of them is a drop-in replacement for the others, so a sprocket stamped for 08B will not seat an ANSI #40 chain even though it appears to fit on a tape measure [S2][S9]. Another trap is using 5/8 in (0.625 in, #50) chain where the drive actually needs 3/4 in (0.750 in, #60); the 1/8 in pitch difference is invisible until the chain rides high on the sprocket teeth and the master link will not seat [S7]. A third trap is using spring-clip connecting links above ANSI 60; press-fit cover linkplates are the standard for ANSI 80 and larger, and spring clips are only rated up through #60 per industry attachment-chain guidance [S4].
Selection by drive power, speed, and center distance
For light fractional-horsepower drives, #40 chain is the default: small machine tools, small conveyors, low-power agricultural implements, and similar applications running below roughly 1 hp at shaft speeds under 500 rpm, where 3,970 lb of tensile and 0.500 in pitch are sufficient and the lighter mass reduces bearing load [S2][S3]. As the drive moves into the 1–5 hp range with higher torque pulses, #60 chain at 9,270 lb tensile is the typical step up, used in larger conveyors, industrial fans, and small mixers where the 0.750 in pitch still fits within common sprocket bores [S3][S6].
For heavier industrial service, #80 chain at 16,540 lb tensile covers drives in the 5–15 hp range with moderate shock loading, and it is also the size at which cottered connecting links become the standard rather than spring clips [S3][S4]. Above the working envelope of #80 in single-strand, the correct move is a duplex or triplex strand on the same pitch (80-2, 80-3) rather than jumping to #100, because the same sprocket tooth form carries the load across multiple strands on a wider plate pack [S2][S6]. Renold Jeffrey's single-strand horsepower table for #60 single-strand shows ratings of roughly 1 hp at 1,000 rpm up to about 6 hp at 50 rpm before the 9,270 lb tensile envelope is approached, which lines up with the conservative 10–15% tensile working-load rule [S6]. A typical 13-pitch section of ANSI 60 chain measures 9.75 in nominal length, the baseline used in attachment-chain layout and 3% wear-extension checks per industry application guidance [S4].
Comparison: #40 vs #60 vs #80 single-strand at a glance
The three sizes differ on five criteria that drive every selection decision, all drawn from ASME B29.1-2011 and manufacturer data: pitch, roller diameter, pin diameter, minimum tensile strength, and weight per foot [S2][S3][S5].
Criterion 1, pitch: #40 at 0.500 in (12.70 mm), #60 at 0.750 in (19.05 mm), #80 at 1.000 in (25.40 mm); a 1.5x step between #40 and #60 and the same 1.33x step between #60 and #80 [S2][S3]. Criterion 2, roller diameter: 0.312 in, 0.469 in, 0.625 in, scaling with pitch so sprocket selection is fixed by chain size [S3]. Criterion 3, pin diameter: 0.156 in, 0.234 in, 0.312 in, the dimension that sets fatigue life [S3]. Criterion 4, minimum tensile strength: 3,970 lb, 9,270 lb, 16,540 lb, a 2.3x step from #40 to #60 and a 1.78x step from #60 to #80 [S2][S3]. Criterion 5, weight per foot: 0.42 lb/ft, 0.97 lb/ft, 1.71 lb/ft, which matters for overhung shaft load and bearing selection on small drives [S3]. On cost, #40 is the cheapest per foot and easiest to source, #60 is the workhorse of general industrial drives, and #80 carries a higher unit cost but is the entry point for cottered heavy-duty service and is also the smallest chain commonly supplied with -2 and -3 strand options for high-torque applications [S3][S4][S6].
When #40, #60, or #80 is the right call, and when it is not
Choose #40 when the existing drive uses 0.500 in pitch sprockets, the motor is below roughly 1 hp, and the duty cycle is light: small conveyors, packaging machines, and fractional-horsepower farm equipment are the sweet spot [S2][S3]. Do not use #40 for drives above about 1.5 hp at moderate speeds, for high-shock loads such as press drives, or anywhere the existing sprockets are 0.750 in pitch, because the chain will not seat and the master link will refuse to close [S2][S7].
Choose #60 when the drive is in the 1–5 hp range, when 9,270 lb of tensile is required for shock margin, when existing sprockets are 0.750 in pitch, and when duplex or triplex options (-2, -3) are likely to be needed for future load growth [S3][S6]. #60 is the most commonly used size in general industrial power transmission and the most widely stocked, which is also a procurement argument for it [S1][S6]. Do not use #60 where 1.000 in pitch sprockets are already in the drive, where the working load is well under 1,000 lb and pitch precision is the limiting factor (use #40 instead), or where heavy series 60H is required for additional plate thickness on shock-loaded service [S2][S8].
Choose #80 when the drive is in the 5–15 hp range, when shock loading and continuous torque push the working load above roughly 1,600 lb, when 1.000 in pitch sprockets are already mounted, and when cottered connecting links are the desired standard for serviceability [S3][S4]. Do not use #80 for light fractional-horsepower service, because the 1.71 lb/ft mass adds unnecessary bearing load, and do not substitute #80 for 60H if the actual requirement is heavy-series plate thickness on a 0.750 in pitch drive [S3][S8]. For a detailed comparison of how different chain standards handle dimensioning versus load rating, the encyclopedia roller chain reference is the starting point, and tapered roller bearing selection for the supporting shafts is the usual next decision after the chain size is fixed.
Verification: how to confirm chain size on the bench
Pitch is the first measurement: lay the chain flat, apply the chain's rated measuring load, and measure center-to-center over 10 to 12 pitches then divide by the number of pitches; a 0.500 in pitch reading identifies the chain as either #40, #41, or metric 08B, and the next three measurements separate them [S2]. Roller diameter is the second check: caliper the outside of the roller (or bushing on #25 and #35) at its widest point; #40 reads 0.312 in, #60 reads 0.469 in, and #80 reads 0.625 in, which alone confirms the chain number within the 40/60/80 family [S2][S3].
Width between inner plates is the third check, measured at the inner link, not across the outer plates: 0.312 in for #40, 0.500 in for #60, and 0.625 in for #80 [S3]. Pin diameter is the fourth and most discriminating check, measured through the plate hole: 0.156 in for #40 (versus 0.141 in for the look-alike #41), 0.234 in for #60, and 0.312 in for #80 [S2][S3]. If all four dimensions match within tolerance, the chain is positively identified; if only pitch matches, the chain is not the size its stamp suggests and the existing sprockets are not a guaranteed match [S2]. Attachment-chain inspection uses the same dimensions plus a 3% maximum wear check, so a chain that has elongated more than 3% over its nominal pitch length is at end of service life regardless of which of the three sizes it started as [S4].
Track these signals over the next procurement cycle: first, the stocking depth of #40 versus #60 at general industrial distributors, since #60 is the workhorse and any lead-time shift there is the leading indicator of supply tightness across the family [S1][S6]. Second, the availability of heavy-series 60H and 80H for shock-loaded service, because H-suffix chain is the standard move when standard-series plate thickness is the limiting factor on a 0.750 in or 1.000 in pitch drive [S2][S8]. Third, the duplex and triplex strand options on #60 and #80, which are the path for high-torque growth without changing the sprocket pitch and which share the roller conveyor and crossed roller guide sprocket-bore standards across strand counts [S2][S4].