What size blazer do I currently have?
On some of our blazers, the size label can be found in the inside zip pocket. Locate the label with the washing instructions on, and right at the very top of that label you will find the size. It is hidden under the teeth of the zip. It will read something like 14/36. This would be a 36" Blazer.
Please note it is not the smaller label underneath which reads "104 12/18 KB1F" or something similar. This is the manufacturer's batch and product code. If the washing instruction label is not there, then it is likely that it has been ripped out or caught in the zip.
We have recently had the label moved to one of the inside seams of the jacket lining. This should be easier to locate if you have one of these blazers.