How to Choose a Door Lock Cylinder (A-B Measurement)?

AKZERN YAPI

When replacing a door cylinder (barrel), choosing the correct size is critical for both security and installation. For Euro profile cylinders, the measurement is expressed as the A and B distances from the screw hole in the center of the body to each side (e.g., 30-40 mm).

How to determine the A-B measurement?

Measure the lengths of the existing cylinder on the door separately, from the center of the retaining screw in the lock case to the inside (A) and to the outside (B). The cylinder should not protrude more than 2-3 mm from the door surface; a cylinder that protrudes too much creates a security vulnerability.

Choose the right cylinder

For system/lever cylinders and nickel/satin options, see our door cylinders (barrels) collection.
For replacement along with the lock body, explore the door locks and locks and security categories.

To enhance security, cylinders with steel pin reinforcement and TS EN 1303 certification should be preferred.