Letterbox lock cam size: how to measure
Online listings quote sizes such as 16 mm, 20 mm or 30 mm, but sellers measure different things. Here’s what to check.
Updated
Two numbers people confuse
- Body length: how far the lock barrel passes through the door. It must suit the door thickness.
- Cam length: how far the flat bar reaches behind the frame. It must overlap the frame enough to hold the door.
Ask the seller which one their “16 mm” or “20 mm” refers to before you buy.
How to measure
- Open the mailbox.
- Measure door thickness at the lock hole.
- Measure from the centre of the lock hole to just past the frame edge it locks against.
Not sure? Send a photo of the front and inside of the door. We confirm the fit in writing before we travel.
FAQ
Can you match the existing lock on my letterbox?
In most cases, yes. Send one straight-on photo of the mailbox front and we identify the cut-out, cam type and turning direction, then confirm in writing which model fits. If we confirm a model and it does not fit on site, you pay nothing, including no attendance fee.