Fareed Mohmed · Engineering
Chain and Sprocket Selector
Power · Speed · Chain · Sprockets · Length
Enter the power, the input and output speed, what drives the chain and what it drives. The tool sizes a roller chain drive: the chain number and strands, the sprocket teeth and diameters, the chain speed and pull, the safety factor, the chain length in links, the exact centre distance, the wrap on the small sprocket and the lubrication. Every calculation step is shown.
Six ways to size: standard formulas for ANSI B29.1 (chains 35 to 120) and ISO 606 B series (08B to 32B) chains of any brand, the Rexnord Quality Chains catalogue (ISO, ANSI, H and HE series), the Renold roller chain catalogue (ISO, ANSI and heavy), the Tsubaki RS catalogue (ANSI 25 to 240), the MISUMI Economy series (rated from its kW tables), and the Diamond Series catalogue (standard and heavy series, rated from its horsepower tables). Service factors come from ISO 10823. Use the result to choose the size, then confirm it with your chain supplier’s rating and part number. This sizes industrial machines only.
Start Here: The Selection Process
Ten steps from the duty to the order, in the order the tool works. Read this once, then use sections 01 and 02. Steps with a button link to where you enter or read that step. Step 10 is done outside the tool.
Gather the duty
Write down what the chain must do before touching the tool.
- Power to transmit, in kW, at the input shaft
- Input speed and the output speed you need, in RPM
- What drives it (motor, engine) and what it drives (conveyor, mixer, press)
- Space: the centre distance you have, in mm
Pick the service factor
The load is rarely smooth. A service factor from 1.0 to 2.1 multiplies the power, so the chain is sized for the real duty. It depends on the driver and the driven machine.
Fix the speed ratio
Ratio = faster shaft speed ÷ slower shaft speed. The large sprocket has the ratio times as many teeth as the small one. Keep one stage under about 7:1. A bigger ratio needs two stages.
Choose the small sprocket teeth
Teeth set how smoothly the chain runs. Fewer teeth means more chain speed variation and wear.
- 17 teeth is the lowest sensible number; 19 is the usual start
- At high speed or with shocks, use 25 or more and hardened teeth
- The large sprocket should not exceed 114 teeth
Check the chain rating
A chain has a power rating that depends on its pitch, the teeth of the small sprocket and the small sprocket speed. For the standard formulas the tool takes the lower of two limits: plate fatigue (slow, heavy) and roller and bush impact (fast). Required rating = power × service factor ÷ strand factor. With the Diamond catalogue the rating is read from Diamond’s table instead.
Check chain speed and pull
Chain speed v = teeth × pitch × RPM ÷ 60000, in m/s. Pull = power ÷ speed. The tool adds the centrifugal tension and compares the total with the chain’s minimum breaking load.
Set the centre distance and chain length
A centre distance of 30 to 50 pitches is best. The small sprocket should wrap at least 120°. The chain length is counted in links and rounded up to an even number, so no offset link is needed. Then the exact centre distance is recalculated.
See the geometry in section 05 →Choose the lubrication
The chain speed decides how it must be oiled: manual or drip at low speed, an oil bath or disc at medium speed, and an oil stream at high speed. Without enough oil the ratings do not hold.
Compare the brands and options
Section 02 checks your duty against every chain in every catalogue and lists the ones that pass, lightest first, with the reason each of the others fails. Section 04 shows the smallest chain that passes for each series and strand count, so you can see the trade: a larger single strand against a smaller multi-strand chain.
See which brands pass in section 02 →Check what the tool does not, then order
- Sprocket bore, hub, keyway and how it fits the shaft
- Chain guards, tensioner or idler, and a way to adjust the centre distance
- Shaft loads on the bearings from the chain pull
- The exact part number from your supplier’s catalogue, and the supplier’s own rating
Six common mistakes
Brands that make this product
Filled gold: loaded in this tool and rated from the catalogue. Outlined gold: loaded in part (Rexnord, Renold and Tsubaki: sizes and strengths, rated by the standard formula). Grey dashed: not loaded yet. Pick a catalogue in section 01 to size with it. The standard formulas also work for any other brand’s ISO 606 or ANSI chain. Confirm the final choice against your supplier’s own ratings. Hover a brand for what is loaded.
Diamondrated
Rexnordpartly
Tsubakipartly
Renoldpartly
MISUMIratedBrand names and logos are trademarks of their owners and are shown only to identify catalogues.
Application
Type the numbers and choose from the lists. The result updates as you change them. Leave the centre distance empty to use 40 chain pitches.
Brands And Chains That Pass
Your duty is checked against every chain in every catalogue loaded. A chain is listed when at least one tooth count and strand count, inside your Strands and Small sprocket teeth settings, passes every check: rating, safety factor, chain speed, teeth, wrap and sprocket clearance. The card for each catalogue shows how many of its chains pass. Click a card to size within that catalogue, or Select on a row to see the full working for that chain in section 03.
Result
Smallest Chain For Each Series And Strand Count
Sprockets, Chain Length And Centre Distance
Sprocket diameters follow from the pitch and the number of teeth. The chain length is counted in links and rounded up to an even number. The centre distance is then recalculated for that length.
Calculation Steps
Every step is worked with your numbers for the chain shown in the result.
How It Is Calculated
Service factor
The corrected power is the power you enter multiplied by a service factor f1 from ISO 10823 Table 2. Rows are the driven machine (smooth, moderate shocks, heavy shocks) and columns are the driver (smooth, slight shocks, moderate shocks). The values run from 1.0 to 2.1.
Strand factor
Several strands share the load, but never perfectly. The factors are 1.7 for two strands, 2.5 for three and 3.3 for four (ISO 10823 and ANSI). The required rating of one strand is Pc = power × f1 ÷ strand factor.
Chain power rating
The tool takes the lower of two limits for one strand of chain at the speed of the small sprocket. Plate fatigue, in hp: H = 0.004 × z11.08 × n10.9 × p(3 − 0.07p), with p in inches, converted to kW. Roller and bush impact, in kW: P = 950 × z11.5 × p0.8 ÷ n11.5, with p in mm. We checked the fatigue formula against the published ANSI horsepower tables for chains 35, 60, 80 and 100, and the impact formula against chains 80 and 100. Both reproduce the table values to three figures. The ratings assume a chain of about 100 to 120 pitches, a speed ratio from 1:3 to 3:1, good lubrication, a 15,000 hour life and an ambient temperature of −5 to 70 °C.
ISO B series ratings
The same formula is used for the ISO B-series chains. Their plates are as thick as, or thicker than, the ANSI chain of the same pitch, so the figure is on the safe side. Chain manufacturers print their own ratings for each chain, so use those for the final choice.
Chain speed, pull and safety factor
Chain speed v = z × p × n ÷ 60000 in m/s. Pull Ft = 1000 × P ÷ v in N. The tool multiplies the pull by the service factor, divides by the strand factor, and adds the centrifugal tension Fc = q × v², where q is the chain mass per metre. The safety factor is the minimum breaking load divided by that total. The required value you choose is the tool’s own rule of thumb, not a value from a standard.
Sprocket geometry
Pitch diameter d = p ÷ sin(π ÷ z). Outside diameter da = p × (0.6 + cot(π ÷ z)). Root diameter = d − roller diameter. The speed variation from the chain wrapping a polygon is (1 ÷ cos(π ÷ z) − 1) × 100 %, about 1.4 % at 19 teeth.
Chain length and centre distance
Links L = 2C/p + (z1 + z2)/2 + [(z2 − z1)/(2π)]² × p/C, rounded up to an even number. The exact centre distance for L links is C = p/4 × [ (L − (z1+z2)/2) + √( (L − (z1+z2)/2)² − 8 × ((z2 − z1)/(2π))² ) ]. Wrap on the small sprocket = 180 ° − 2 × asin((D2 − D1) ÷ 2C).
Lubrication
Chain speed up to 4 m/s: manual or drip feed (Type A). Up to 8 m/s: oil bath or disc (Type B). Above 8 m/s: oil stream (Type C). These bands are approximate and depend on the pitch, so take the lubrication chart from your chain supplier.
Diamond catalogue method
Diamond Chain prints a power table for each chain in kW and hp: one row for each small-sprocket tooth count (11 to 45) and one column for each speed. The tables assume a service factor of 1, 100 pitches of chain, the recommended lubrication, a clean place and about 15,000 hours of life. The tool reads the table between the printed speeds on a log scale and between the tooth counts in a straight line. Above the last speed printed for a tooth count the chain is not rated. A few cells at the end of a row in the printed tables show a value far lower than the cell before it. They look like misprints, so the tool leaves them out. Diamond lists average tensile strength, not the minimum. Its multi-strand factors are 1.7, 2.5 and 3.3. Diamond gives no service factors, so the tool uses the ISO 10823 ones.
Rexnord catalogue method
The Rexnord Quality Chains catalogue gives dimensions, minimum ultimate strength and mass for ISO 606 chains (06B to 48B), ANSI chains (40 to 240) and the H and HE series, but no power ratings. Rexnord says that tensile strength is not a good basis for choosing a chain and that fatigue strength is, which it gives on request. The tool therefore rates Rexnord chains with the standard formulas. For the H and HE series, whose link plates come from the next larger chain, Rexnord states about 40 % more permitted load, so the plate-fatigue limit is raised by 40 %. The impact limit is not. Ask Rexnord for its own rating before ordering.
How the tool picks the chain
It tries each chain from the smallest pitch up, with 1, 2 and 3 strands (or the number you pick), and the small sprocket teeth you pick. It keeps those where the rating, the safety factor, the speed, the wrap and the tooth limits all pass. From those it chooses the lightest chain (strands × mass per metre) as a rough guide to cost.
What is not covered
Sprocket bore and hub, shaft and bearing loads, chain tension and sag, idlers, chain guards, shock loads above the service factor, temperatures beyond the rating range, corrosive or dusty environments, double-pitch and attachment chains, and the exact part numbers of any brand.
Renold catalogue method
The Renold catalogues give dimensions, minimum tensile strength and mass for ISO 606 / BS chains (05B to 40B), ANSI chains (25 to 240) and the heavy H series (60H to 140H), but no power ratings. Renold publishes the rating in its online selector and designer guide, which are not in the files loaded here. The tool therefore rates Renold chains with the standard formulas, the same as for any ANSI or ISO chain. Heavy-series strengths were printed in kgf and are converted to kN. Renold Synergy and ANSI Xtra chains have the same dimensions and tensile strengths as the standard tables but carry higher ratings from Renold, so the result for them is on the safe side. Check the final choice with Renold.
Tsubaki catalogue method
The Tsubaki Drive Chains and Sprockets catalogue gives dimensions, strength and mass for RS roller chain, and kW rating tables for each size. In the file loaded here the tables are broken up and only partly readable, so the tool loads the RS 25 to 240 single-strand sizes, minimum tensile strengths and masses, and rates them with the standard formulas. In the readable tables (RS25 and RS35), Tsubaki rates the chain from equal to the formula up to about 60 % above it in the fatigue range, and about 70 % above in the impact range. The tool result is therefore on the safe side. Take the final rating from the Tsubaki table. Not loaded: ISO B series RS, heavy, lube-free, Lambda and corrosion resistant chains.
MISUMI catalogue method
MISUMI Economy series roller chain (C-CHE) is rated from the transmission capacity tables on pages B-042 to B-046 of the MISUMI Promobook: ANSI 35, 40, 50, 60 and 80, and ISO 06B, 08B, 10B, 12B, 16B and 20B, single strand, for 9 to 45 teeth and 10 to 10,000 rpm. The tool reads the table between the listed speeds and tooth counts, and gives zero rating where the table is blank. MISUMI gives these ratings for minimum load variation, clean air between -10 and 60 °C and the recommended lubrication, so the tool still applies the ISO 10823 service factor on top. The printed table has coloured lubrication zones that do not survive in the text, so check the lubrication type against the MISUMI table. Multi-strand ratings use the same strand factors as the other catalogues. Strength and mass are the ISO 606 and ANSI values. Not loaded: C-CHE 25, the Economy sprockets and the stainless chains.
Sources
ISO 606 and ANSI B29.1 roller chain dimensions and minimum tensile strengths. ISO 10823:2004 for the service factors, strand factors, the 15,000 hour rating basis and the tooth limits (17 to 114 teeth). ANSI horsepower rating tables (American Chain Association) used to check the rating formulas. Rexnord Quality Chains catalogue (about 2009): dimensions, minimum ultimate strength and mass of ISO 606, ANSI, H and HE chains. MISUMI Economy Series Promobook 2025 (chain pages 08-007 to 08-013 and technical data B-039 to B-046). Tsubaki Drive Chains and Sprockets catalogue (RS single-strand tables). Renold Roller Chain Catalogue (ISO 606 and ANSI tables) and Renold Transmission Chain Catalogue (heavy series). Diamond Chain Diamond Series Product Catalog: chain tables (pages 9 to 14) and horsepower tables (pages 52 to 75).
Chain Data Used
The values behind the choice, for the catalogue you picked in section 01.