Buying a new lock cylinder? Read our guide.

Lock cylinders play an important part in your home or office security. This straightforward guide will tell you all you need to know before you buy.

How to Measure

Buying the right size cylinder is important. If it's too long, you risk compromising your security because if it protrudes more than 5mm, the cylinder is vulnerable to snapping. Too short and you won't be able to turn the key.

How to Measure

Measuring to replace a cylinder

Replacing a cylinder? Print out our Measuring Tool and place your cylinder where indicated to get the exact dimensions.

When A and B are the same dimension, you need an Equal Cylinder. If they're different, you need an Off-Set Cylinder.

Download Measuring Tool

Measuring for a new cylinder

If you're measuring for a new door, you'll need to consider the door's width and any door furniture, such as handles or escutcheons.

Measure from the outside edge of the door (including furniture) to the centre of your door. This is dimension A and is called the External Size to Centre.

Next, measure from the inside edge of your door (including furniture) to the centre of your door to find dimension B, the Internal Size to Centre.

As a final check, measure from the outside edge to the inside edge (including all furniture) to find dimension C called the Overall Length.

If you've measured correctly the overall length, C, will be dimensions A and B combined.

For an extra helping hand, check out our How to measure a cylinder video below.

Once you know the size, your next consideration are your security features. Click here for more info.

Found what you need?
Was this article helpful?
👍    👎
Sign up to our newsletter: