Chain pitch is the distance between the centers of two adjacent link pins. Common pitches are 0.25 in (#25), 0.375 in (#35), 0.5 in (#40/41), 0.625 in (#50), and 0.75 in (#60). The chain number is roughly pitch × 80 in imperial units.

Why must the number of links be even?

An even number of links allows the chain to form a closed loop with standard connecting links (also called master links). An odd number would require an offset link, which is weaker and best avoided in power-transmission applications.

What is the corrected center distance?

After rounding the raw link count up to the nearest even number, the actual chain is slightly longer than the calculated minimum. The corrected center distance tells you how far apart to set the shafts so the chain runs with proper tension rather than slack.

What formula does this calculator use?

The standard ANSI/ISO chain length formula: L = (N1+N2)/2 + 2C/p + ((N2−N1)/(2π))² × (p/C), where N1 and N2 are the tooth counts, C is the center distance, and p is the pitch. The result in pitches is rounded up to the nearest even integer.

Can I use metric units?

Yes. Switch the unit selector to millimeters. Enter pitch and center distance in mm — the chain length result will also be in mm. The number of links is unit-independent.

What if the center distance is too small?

The minimum recommended center distance is about 30–50× the pitch for most drives, and must be greater than half the sum of the two sprocket pitch diameters. The calculator will show an inline warning if the center distance is too small for the given sprockets.

Chain Length Calculator

Enter sprocket teeth counts, chain pitch, and center distance to instantly find the required chain length and number of links.

Drive Parameters

Unit System

Driver (Small) Sprocket Teeth N₁

Driven (Large) Sprocket Teeth N₂

Chain Pitch (in)

Common: 0.25 (#25), 0.375 (#35), 0.5 (#40), 0.625 (#50), 0.75 (#60)

Center Distance (in)

Chain Drive Diagram

Fill in the parameters and click Calculate to see results.

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Summary

Enter sprocket teeth counts, chain pitch, and center distance to instantly find the required chain length and number of links.

How it works

Enter the number of teeth on the small (driver) sprocket.
Enter the number of teeth on the large (driven) sprocket.
Enter the chain pitch — the distance between link pins (e.g. 0.5 in for #40 chain).
Enter the center distance between the two sprocket shafts.
The calculator applies the standard ANSI chain length formula and rounds links up to the nearest even number.
The corrected center distance for the rounded link count is shown so you can set your tensioner accurately.

Use cases

Sizing roller chain for a bicycle, go-kart, or mini-bike drivetrain.
Designing conveyor or power-transmission chain drives in machinery.
Replacing a worn chain — find the exact link count before ordering.
Checking whether an existing chain is long enough after repositioning sprockets.
Verifying center-distance adjustments when swapping to a different sprocket ratio.
Teaching mechanical engineering students the chain drive design process.

Frequently Asked Questions

Last updated: 2026-09-22 · Reviewed by Nham Vu