Chain Length (Link Count) Calculator
Calculates the number of chain links needed from sprocket teeth and centre distance, and the resulting axle position.
Free · No sign-upMotorcycle chains are sold by size and link count: '428H – 130L', for example, is a heavy-duty 428 chain with 130 links. The right link count depends on the number of teeth on both sprockets and the distance between their centres.
Because the chain ends are joined with a standard master link, the link count must be even. The calculator finds the exact value, recommends the even count that keeps the axle closest to where you measured, and shows the other option too.
Pitch 15.875 mm
Front sprocket shaft ↔ rear axle centre
Calculated links
106.19
Unrounded value
Recommended
106 links
Axle at 598.4 mm (-1.6 mm)
Alternative
108 links
Axle at 614.4 mm (+14.4 mm)
When ordering, state both the chain size and the link count, e.g. 520 – 106L. Make sure your adjusters can reach the new axle position.
How it is calculated
The first digit of the chain size gives the pitch (pin-to-pin distance) in eighths of an inch: 4xx = 1/2 in = 12.7 mm, 5xx = 5/8 in = 15.875 mm, 6xx = 3/4 in = 19.05 mm. The last two digits relate to the roller width; 'H' means heavy-duty.
The centre distance is the straight-line distance from the centre of the front sprocket shaft to the centre of the rear axle. Measuring with the chain adjusters in the middle of their range leaves adjustment in both directions.
The formula gives an unrounded link count. The inverse formula then finds where the axle would sit with the next even counts below and above; the one closest to your measurement is recommended.
Formula
- L = 2C ÷ p + (Z1 + Z2) ÷ 2 + p × ((Z2 − Z1) ÷ 2π)² ÷ C
- C = p ÷ 4 × [ (L − (Z1 + Z2) ÷ 2) + √((L − (Z1 + Z2) ÷ 2)² − 2 × ((Z2 − Z1) ÷ π)²) ]
- L: link count · C: centre distance (mm) · p: pitch (mm) · Z1, Z2: front and rear teeth
Worked example
- 1520 chain (p = 15.875 mm), 15-tooth front, 45-tooth rear, 600 mm centre distance
- 22 × 600 ÷ 15.875 = 75.59; (15 + 45) ÷ 2 = 30; 15.875 × (30 ÷ 6.283)² ÷ 600 = 0.60
- 3Total ≈ 106.19 links
- 4106 links: axle ≈ 598.4 mm (−1.6 mm) → recommended; 108 links: axle ≈ 614.4 mm (+14.4 mm)
Good to know
- Every 2 teeth changed on the rear sprocket correspond to about 1 chain link.
- The chain and both sprockets wear together; running a new chain on worn sprockets shortens its life considerably.
- Use a proper chain breaker/riveting tool to shorten the chain and fit the master link. On powerful bikes a riveted master link is safer than a clip-type one.
Frequently asked questions
Why must the link count be even?
A chain alternates inner and outer links. To join both ends with a standard master link, one end must be an inner link and the other an outer link, which means an even number of links. An odd count is only possible with an offset (half) link, which is not recommended on motorcycles.
What is the difference between a 428 and a 520 chain?
A 428 chain has a 12.7 mm pitch and a 520 chain a 15.875 mm pitch. The 520 is larger and stronger and is usually used on motorcycles of 250 cc and above. The chain size must match the sprockets: a 520 chain does not fit 428 sprockets.
How do I measure the centre distance?
Set the chain adjusters to the middle of their range and measure the straight distance from the centre of the front sprocket shaft to the centre of the rear axle. If you know the old chain's link count, the inverse formula lets you double-check the distance.
How do I know the chain needs replacing?
If the adjusters are at the end of their travel, the chain can be pulled well away from the back of the rear sprocket, links are stiff or rusty, or the sprocket teeth are pointed or hooked, replace the chain and sprockets together.
Results are for information only and are based on theoretical calculations. For parts and maintenance, follow your motorcycle's owner's manual and the manufacturer's specifications. Last reviewed: October 8, 2026
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