Roller Blind Chain Connector Size Guide: 3.2mm or 4.5mm?

C&J REPAIRS • PRACTICAL FITTING GUIDE

A snapped roller blind chain connector is a small problem, but choosing the wrong bead size can leave the chain unable to join securely. The important measurement is the size of the chain beads, not simply the width of the cord.

White replacement roller blind beaded chain connector

What is the difference between 3.2mm and 4.5mm connectors?

Our replacement connector range includes options described for 3.2mm and 4.5mm beaded roller blind chains. Those figures refer to different bead sizes. They should not be treated as interchangeable, and a connector that looks similar in a photograph may not grip an incorrectly sized chain.

How to measure a roller blind chain

Locate a clean, undamaged bead away from the broken joiner.
Measure across the widest part of the round bead using digital callipers if available. A ruler can offer a rough indication, but is less reliable for small differences.
Measure several beads to allow for wear or manufacturing variation. Record the bead diameter in millimetres.
Compare the result, the gap between beads and the overall connector shape with the photographs and dimensions in the relevant product listing.

Measure the bead, not the string. A connector sold for a particular bead diameter does not automatically fit every chain with beads of approximately that size. Bead spacing and connector geometry still matter.

How to replace a broken beaded-chain joiner

Check that the chain itself is intact and that the blind operates correctly.
Identify whether the existing component is a simple joiner or part of the blind's safety system. Do not remove or bypass safety devices.
With the blind stationary, remove the damaged joiner and fit only a connector suited to the chain design, following any manufacturer instructions.
Test the chain gently. Stop if the beads slip out or the chain binds in the mechanism.

Common questions

Will any white connector fit my blind?

No. The colour and general appearance are not enough to establish compatibility. Bead dimensions and the fitting design must match.

Can I use a larger connector on a smaller chain?

We would not recommend assuming that this is safe or secure. Select a connector for the measured chain and check the listing.

What about child safety?

Blind chains can pose a strangulation risk. Follow the blind manufacturer's child-safety guidance and ensure any required tensioning, breakaway or other safety components remain correctly fitted. A replacement joiner should not be used to bypass these devices.

For further guidance, see how to match your replacement part or our Perfect Fit handle spacer guide.