Determining the Lock Backset
The backset is the distance between the axis around which the handle rotates and the axis around which the key turns in the lock, measured in millimeters. This distance determines the spacing between the handle and the keyhole. According to Czech standards, three types of backsets are commonly used: 72 mm, 90 mm, and 92 mm. The 72 mm backset is the most common for interior doors, while the 90 mm backset is typically used for entrance and specialized doors. The 92 mm backset is rare and mostly found in security fittings.
TIP: In our selection of interior and specialty doors, you can find the backset measurement for each door model in the product details section under the "Description" tab.
 | Determining Backset via the Handle Measuring the backset using the handle is useful when replacing existing door fittings. Carefully identify (using the diagram) the axis of the upper handle and the lower keyhole, then measure the distance between them. The measured distance represents the backset. The backset needs to be determined only when purchasing backplate door handles. PZ - Handle set with a keyhole for a cylinder lock BB - Handle set with a keyhole for a standard key WC - Handle set for toilets or bathrooms |
.png) | Determining Backset via the Mortise Lock Measuring the backset via the mortise lock is a more precise method, especially useful when purchasing new doors that have not yet been fitted with door hardware. Mark the axis at the handle hole and the axis at the lower keyhole, then measure the distance between these axes. The measured distance represents the backset. The backset needs to be determined only when purchasing backplate door handles. |