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Roller Chain Length Calculator

Chain length in pitches and millimetres from sprocket teeth and centre distance — rounded to an even pitch count, ANSI #35 to #80.

0
Exact length (pitches)
0
Use (even pitches) (links)
0
Chain length (mm)

Always round UP to an even number of pitches: an odd count forces an offset (cranked) link, which is the weakest piece of chain money can buy — most manufacturers de-rate the drive 30 % the moment one goes in. Take up the slack the even count creates by adjusting the centres or the tensioner. The (z₂−z₁)² term is tiny for mild ratios but real for big reductions on short centres.

Formula

L [pitches] = 2C/p + (z₁+z₂)/2 + ((z₂−z₁)/2π)² · p/C — round UP to an even number
References: ANSI/ASME B29.1 — Precision power transmission roller chains; Shigley's Mechanical Engineering Design, 11th ed.

Chain length in pitches and millimetres from sprocket teeth and centre distance — rounded to an even pitch count, ANSI #35 to #80. A free machinist & fabrication essentials tool — no sign-up, no upload, instant results in your browser.

About Roller Chain Length Calculator

Roller Chain Length Calculator computes the governing relationship L [pitches] = 2C/p + (z₁+z₂)/2 + ((z₂−z₁)/2π)² · p/C — round UP to an even number live as you type. Always round UP to an even number of pitches: an odd count forces an offset (cranked) link, which is the weakest piece of chain money can buy — most manufacturers de-rate the drive 30 % the moment one goes in. Take up the slack the even count creates by adjusting the centres or the tensioner. The (z₂−z₁)² term is tiny for mild ratios but real for big reductions on short centres. Defaults are pre-filled with realistic values for this exact scenario, and the worked example substitutes your numbers step by step so the math is never a black box.

How to use Roller Chain Length Calculator

  1. 1Enter your values — Chain pitch, Small sprocket teeth, Large sprocket teeth, Centre distance (sensible defaults are pre-filled).
  2. 2Read the live results: Exact length, Use (even pitches), Chain length.
  3. 3Check the "with your numbers" line to see L [pitches] = 2C/p + (z₁+z₂)/2 + ((z₂−z₁)/2π)² · p/C — round UP to an even number substituted step by step.
  4. 4Adjust inputs until the scenario matches yours, then copy or share the result.

Why use Roller Chain Length Calculator?

  • ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
  • ✓Built on the stated formula L [pitches] = 2C/p + (z₁+z₂)/2 + ((z₂−z₁)/2π)² · p/C — round UP to an even number with authoritative sources cited on the page (ANSI/ASME B29.1 — Precision power transmission roller chains; Shigley's Mechanical Engineering Design, 11th ed.)
  • ✓Always round UP to an even number of pitches: an odd count forces an offset (cranked) link, which is the weakest piece of chain money can buy — most manufacturers de-rate the drive 30 % the moment one goes in.
  • ✓SI ⇄ Imperial toggle converts your inputs in place, so you can work in the units your drawings use

Frequently asked questions

What formula does the roller chain length calculator use?+

It evaluates L [pitches] = 2C/p + (z₁+z₂)/2 + ((z₂−z₁)/2π)² · p/C — round UP to an even number, exactly as published. Sources: ANSI/ASME B29.1 — Precision power transmission roller chains; Shigley's Mechanical Engineering Design, 11th ed.. The substituted worked example on the page lets you verify every step against the textbook.

How should I read the result — and how far can I trust it?+

Always round UP to an even number of pitches: an odd count forces an offset (cranked) link, which is the weakest piece of chain money can buy — most manufacturers de-rate the drive 30 % the moment one goes in. Treat the output as a planning estimate and verify against the governing documents for your project.

When is this calculator the right tool for the job?+

Chain length in pitches and millimetres from sprocket teeth and centre distance. Take up the slack the even count creates by adjusting the centres or the tensioner. For neighbouring scenarios, the related tools below cover the same engine with different presets.

Does it support both metric and imperial units?+

Yes — the SI ⇄ Imperial toggle converts the values already in the fields, preserving the physical quantity, so you can flip mid-calculation without re-entering anything.

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