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Chain length calculator: roller chain links and centre distance

Number of links of an ISO 606 roller chain, rounded up to an even count, the resulting centre distance, pitch diameters and chain speed. Free, no sign-up.

  • Instant result
  • Formula and standards shown
  • On desktop and phone

Pre-filled example

A chain with a 15.875 mm (5/8 inch) pitch between a 17-tooth sprocket and a 34-tooth wheel, 500 mm apart, the sprocket turning at 300 rpm.

mm
mm
rpm

Result

90Number of links

Actual centre distance
510.16mm
Calculated links
88.72
Small sprocket pitch diameter
86.39 mm
Large sprocket pitch diameter
172.05 mm
Ratio
2.000
Output speed
150 rpm
Chain speed
1.35 m/s
Attach this calculation to a work order

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Chain length filed with the drive's work order

Here, the calculator is free and the result is gone when you close the page. In Reglova, it is attached to the work order on the right machine: you find it again at the next breakdown, and on audit day.

The CMMS software comparison, our gaps included
  • Attached to the work order with its inputs: the server recalculates it, it stays verifiable.
  • On the technician's phone, even without a network.
  • In the machine's history, for the next breakdown.
  • The asset's nameplate data pre-fills the calculation.
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Reglova · Calculations · Work order WO-AT01-04219
Silent video, 33 s: from the work order for an oil leak on a shear cylinder, the tightening torque of an M12 bolt, then "Attach to the work order". A step to tighten it to 93.1 N·m lands in the checklist (step text from the French demo data). Watch the video

When to calculate a roller chain length

  1. 01

    Cut a new chain to the right length.

  2. 02

    Check that a centre distance stays within 30 to 50 pitches.

  3. 03

    Check the chain speed before changing a sprocket.

Good to know

Below 17 teeth on the small sprocket, wear and noise increase. An odd number of links needs an offset link, which weakens the chain.

Chain length formula in pitches

From the chain pitch, the number of teeth on both sprockets and the target centre distance, the calculator gives the number of links, rounded up to an even number to avoid an offset link, then the resulting actual centre distance. It adds the pitch diameters, the ratio and the chain speed.

Formula · Reference documents

X = 2C/p + (z1 + z2)/2 + p·(z2 − z1)²/(4π²·C), rounded up to the next even number ; C = p/4·[a + √(a² − 8·((z2 − z1)/2π)²)], a = X − (z1 + z2)/2 ; dp = p/sin(180°/z)

ISO 606

Inputs and accepted ranges
InputUnitAccepted rangeExample
Pitchmm3 to 20015.875 mm
Small sprocket teeth5 to 20017
Large sprocket teeth5 to 30034
Centre distancemm10 to 20,000500 mm
Small sprocket speedrpm1 to 100,000300 rpm
Calculated results
  • Number of links
  • Actual centre distancemm
  • Calculated links
  • Small sprocket pitch diametermm
  • Large sprocket pitch diametermm
  • Ratio
  • Output speedrpm
  • Chain speedm/s
What the calculator flags
  • Fewer than 17 teeth on the small sprocket: more wear and noise.
  • Centre distance outside 30 to 50 pitches.

Chain and sprocket wear followed in the machine history

  • Breakdowns reported by QR code
  • Work orders on the phone, even without a network
  • Mandatory inspections reminded by email
  • Audit file as a PDF, in one click
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Free during the beta, no credit card