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Instant, private, and free
Bicycle Chain Length Calculator.
Calculate chain length and an even half-inch link count from bicycle geometry.
Set your values
Results update as you type.
Results update automatically as you type.
Use Cases
Replacing a worn chain
When installing a new chain, use this calculator to determine the correct length before cutting. This ensures smooth shifting and prevents chain slap.
Example: If your chainstay is 16.5 inches, front chainring has 50 teeth, and rear sprocket has 12 teeth, the calculator gives the required chain length.
Building a custom bike
For custom builds or frame modifications, this calculator helps you select the right chain length for your specific geometry and drivetrain combination.
Example: A track bike with a 48-tooth chainring and 16-tooth sprocket on a 15-inch chainstay will need a specific chain length.
Frequently Asked Questions
- How do I measure chainstay length for the calculator?
- Measure the distance from the center of the bottom bracket to the center of the rear axle. This is typically measured in inches and is a key input for the chain length calculation.
- What is the formula used to calculate chain length?
- The calculator uses a standard formula that combines chainstay length, front chainring teeth, and rear sprocket teeth. It accounts for the half circumference of the chainring and sprocket, plus the distance between them.
- Can I use this calculator for any type of bicycle?
- Yes, this calculator works for most standard bicycles with a single front chainring and rear sprocket. For multi-speed bikes with derailleurs, the result is a good starting point, but you may need to adjust for your specific drivetrain.
Tips & Common Mistakes
Tips
- Measure chainstay length accurately from the center of the bottom bracket to the center of the rear axle, in inches.
- Double-check the tooth counts on your chainring and sprocket; they are usually stamped on the components.
- For bikes with rear suspension, consider the chainstay length at the sag point for a more accurate result.
- Always add a couple of links to the calculated length if you plan to use a derailleur, to allow for proper tension.
Common Mistakes to Avoid
- Using the wrong unit for chainstay length; ensure it is in inches as the calculator expects.
- Forgetting to include the rear sprocket tooth count, which significantly affects the chain length.
- Assuming the calculated length is exact for all bikes; always check with your specific drivetrain setup.
Last updated: August 13, 2026