Buy the Right Size Cylinder – All you need is a metric ruler.

It is possible to place the ruler against the open edge of the door and use your eye to judge the measurements from the outside face of one backplate to the cylinders fixing screw and from the fixing screw to the outside face of the other backplate.

However, we do not recommend this technique. Instead, we suggest that you take the cylinder out, particularly as it only takes a few minutes and gives the most accurate measurement.

Top Tip – Measure from the Existing Cylinder

Before the cylinder is removed for accurate measurement, check that the cylinder does not stick out significantly from the handle backplate. Ideally, the cylinder should sit flush or just slightly protruding. A cylinder should never stick out more than 5mm*

Euro cylinders are held in place by a Fixing Bolt that is screwed from the door edge through a threaded hole on the side of the cylinder under the cam. The cylinder size required is determined by the distance from each edge of the cylinder to the centre of the Fixing Hole.

. * Mark Long Cylinders – If the cylinder sticks out more than 5mm then use a pencil to clearly mark the cylinder at the point that it leaves the backplate. This mark should then be used for measuring, rather than the end of the cylinder.
2. Remove the Euro Cylinder – If you are unsure how to, click here.
3. Lay the Cylinder Down – Place cylinder on it’s side for measuring.
4. Get Measurement (a) – Measure from the left end of the cylinder to the centre of the Fixing Hole. If you marked the left side of the cylinder with a pencil, then measure from the mark rather than the end.
5. Get Measurement (b) – Measure from the centre of the Fixing Hole to the right end. If you marked the right side of the cylinder with a pencil, then measure to the mark rather than the end.
6. Check Measurements – Measure the overall length required, either from end to end or between pencil marks if marks were made. The overall length should equal the sum of measurements (a) and (b).

If measurement a = 35mm and measurement b = 45mm then the size required is referred to as 35/45 (80mm overall).

Measuring to the Fixing Hole is the most common method of measuring cylinders.
However, some people do not include the 10mm cam space in the centre of the cylinder. Therefore, they would refer to the example above as 30/10/40 (80mm overall). Always check with suppliers when placing an order for cylinders.

Check the style of your cylinder, most common in upvc style doors are double euro & euro and turn.