Cylinder size calculator

A euro profile cylinder is measured by sides, always from the centre of the screw that holds it in place on the edge of the door. So a 30 x 40 cylinder measures 30 millimetres to one side and 40 to the other.

How to take the measurement

1. Open the door and find the long screw on the edge that holds the cylinder, level with the lock.
2. Measure from the centre of that screw to the outer end of the cylinder, or to the outside face of the door or the escutcheon if the cylinder already sticks out.
3. Do the same towards the inside.
4. Enter both measurements in millimetres in the calculator.

What the result tells you

The calculator rounds each side up to the nearest standard size, because a cylinder that is too short does not reach the cam. It also warns you if it would protrude more than 3 millimetres on the outside: a cylinder that sticks out is the easiest to snap or pull out, and in that case the best option is to fit a protective escutcheon or adjust the size.

Bear in mind that this is an approximate measurement. Security doors, aluminium doors and doors with an escutcheon can change the figures. If you send us a photo of the cylinder and the edge of the door on WhatsApp, we confirm the size before we change the cylinder.