“Which mount size do I need?” might be the question we field the most, and honestly, we love that it comes up so often. It means people are being careful with what they collect.
Here’s the trick: measure the stamp itself, not the perforations, in millimeters, width first, then height. Round up to the next available size rather than down. A mount that’s a touch roomy still holds securely; one that’s too tight will crease the stamp or refuse to close cleanly. Mounting a block, strip, or souvenir sheet? Same idea, just measure the whole piece.
A pattern worth knowing: most single commemoratives land in the smaller strip sizes, while blocks and souvenir sheets usually want the wider strips or pre-cuts. Stuck between two sizes? The wider one is almost always the safer bet.
Once you’ve got your number, our mounts are sorted by exact size, so you can go straight to the right one instead of guessing.