Inputs
What it uses
- Chainstay length
- Largest chainring
- Largest sprocket
Maintenance / Available now
Chain-length calculator
Estimate derailleur-chain length from chainstay, chainring and sprocket size.
Your inputs
Calculate a starting point.
Estimated result
Supporting information
Know what shapes the result.
The conventional derailleur formula combines chainstay length, the largest chainring and sprocket, then rounds up to a usable even link count.
Best used for
A practical starting point
Getting a first chain-length estimate before checking the actual bicycle in its largest combination.
Limitations
Check the context
Suspension growth, unusual drivetrains, routing and manufacturer instructions can require a different length. Always verify before cutting.
Before you rely on it
Three useful questions.
What does the chain-length calculator do?
Estimate derailleur-chain length from chainstay, chainring and sprocket size.
How does this tool work?
The conventional derailleur formula combines chainstay length, the largest chainring and sprocket, then rounds up to a usable even link count.
What are the limitations?
Suspension growth, unusual drivetrains, routing and manufacturer instructions can require a different length. Always verify before cutting.