Chain Length Calculator
Chain links & sizing
This free chain length calculator works out how many links your motorcycle drive chain needs from the front and rear sprocket sizes, the axle-to-countershaft centre distance and the chain pitch. It rounds up to the nearest even link count and tells you whether a 112, 114, 116 or 118-link chain is long enough — handy before ordering a chain or changing sprockets.
Chain length tips
- Chains are sold in even link counts (112, 114, 116, 118…) because of the master link.
- A bigger rear or smaller front sprocket needs more chain; a smaller rear or bigger front needs less.
- Most full-size MX/enduro bikes run a 520 chain of about 114–120 links — always check your own measurement.
- Replace the chain and both sprockets together for even wear and correct meshing.
How the chain length calculator works
Drive chains are sold by the number of links (pitches). This calculator uses the standard chain-length equation from your front and rear sprocket sizes, the centre distance between the countershaft and the rear axle, and your chain pitch. It returns the number of links you need, rounded up to the nearest even number — chains only come in even link counts because the connecting (master) link joins two roller plates — and tells you which common motocross and enduro chain lengths (112, 114, 116, 118, 120) are long enough.
Remember you can always remove links from a chain that is too long, but you can never add them to one that is too short. When a result lands close to a boundary, choose the longer chain and break it down to fit.
Measuring the centre distance
The centre distance is the straight-line distance between the centre of the front sprocket (the countershaft / gearbox output) and the centre of the rear axle, measured at the chain-adjuster position you actually plan to run. Set the rear wheel roughly in the middle of its adjustment range first — that leaves room to tension the chain as it wears and as you change sprockets. On most full-size enduro and motocross bikes this distance is around 575–610 mm, but always measure your own bike.
Chain pitch and sizing
- 520 / 525 / 530: 5/8 in (15.875 mm) pitch — the standard for nearly all full-size four-strokes and most modern 2-strokes. 520 is the lightest and most common for off-road.
- 420 / 428: 1/2 in (12.70 mm) pitch — used on minicross, 50–150 cc bikes and many youth machines.
- The first digit of the chain number is the pitch; the rest describe roller width and strength. Match the pitch to your sprockets — a 520 chain will not run on 428 sprockets.
When sprocket changes need a new chain
Changing gearing changes the chain wrap. Going to a bigger rear or smaller front sprocket eats up chain and may need a longer chain or a forward axle position; going the other way frees up slack you can take out at the adjusters or by removing a link. After any sprocket change, re-check that the axle still sits within the adjuster marks with correct chain slack — if it is pinned at one end, your chain length is wrong for that gearing.
Chain length — frequently asked questions
How do I know how many chain links I need?
Enter your front and rear sprocket teeth, the centre distance between the countershaft and rear axle, and your chain pitch. The calculator applies the standard chain-length formula and rounds up to the nearest even number of links. Always measure the centre distance with the axle near the middle of its adjustment range.
Is a 114-link chain enough for my bike?
It depends on your sprockets and centre distance. Many full-size 520 bikes need 114–118 links. Enter your numbers above and the tool will show whether 112, 114, 116 or 118 links reach. If you are between sizes, buy the longer chain and remove links.
Why do chains only come in even numbers of links?
A chain alternates inner and outer link plates, and the master link that joins the ends needs a matching pair, so usable chains have an even number of links. That is why the calculator always rounds up to an even count.
Can I make a chain longer?
Not practically — you should never add links to lengthen a worn chain, and joining sections introduces extra weak master links. Always buy a chain at least as long as you need and remove links to fit. That is why this tool errs toward the next length up.
Do I need a new chain when I change sprockets?
Often, yes. Larger gearing changes alter how much chain is wrapped, so the axle can end up outside its adjustment range. Re-run the calculator with the new sprockets; if the required length crosses your current chain, fit the correct length. Replacing chain and sprockets as a set is best practice anyway.