Are hex number plates legal in the UK?

Plate Legality · 5 September 2026 · 5 min read

The angled ends aren't the problem. Whether a hex plate is road legal comes down to the same things as any plate: character size, spacing and the margin around them. Here's where the line is.

Shape isn't the rule

People assume a hex plate can't be legal because it isn't a rectangle. But BS AU 145e doesn't prescribe a shape. It prescribes what has to be on the plate and how much clear space has to surround the registration. A hex plate is legal if it meets those, and illegal if the angled ends eat into them.

We sell hex plates in both forms, and the builder tells you which one you're getting.

What a hex plate has to satisfy

Exactly the same list as a standard plate:

• Characters 79 mm tall, 50 mm wide (14 mm for the 1 and the I), 14 mm stroke, Charles Wright font
• 11 mm between characters, 33 mm between the two groups
• At least 11 mm of clear plate around the whole registration
• Reflective white or yellow background, solid black characters, no tint
• The BS AU 145e mark and the supplier's name and postcode

The margin is the one that matters for a hex. Where the plate tapers to its points, the usable width shrinks. If the registration still sits inside an 11 mm margin with the angled ends outside that, the plate is fine. If the characters have to be shrunk or squeezed to fit, it isn't.

The two kinds of hex plate

Full-width hex. A 520 mm plate with the corners cut to the hex profile. The registration sits in the same place it would on a standard plate, and the angles only remove material from the corners where there's no lettering anyway. This is legal for any registration that would be legal on a standard plate.

Compact hex. A shorter plate whose width follows the number of characters, so the points sit close to the lettering. Five or six characters usually fit with full-size letters and a proper margin. Seven or eight often don't, and at that point the only way to make the plate is with smaller letters, which is a show plate, not a road-legal one.

The builder works this out for you: put the registration in, pick hex, and it will either keep the plate road legal or tell you it has to switch to show plate.

Fitting and holders

Standard plastic clip holders grip a full-height rectangular edge. A hex plate is the right height in the middle but not at the ends, so it either won't clip in or it will flex in the holder. Fit hex plates with pads straight onto the bumper. There's more in the fitting guide.

MOT and police

A legal hex plate passes the MOT the same way any plate does: the tester checks font, spacing, colour, condition and the margin, not the outline. An officer at the roadside is checking the same things. Where hex plates attract attention is when they've been made with small or squeezed characters, which is a genuine offence regardless of shape.

Short version

Full-width hex: legal for any registration. Compact hex: legal for shorter registrations, show plate for longer ones. Either way, the builder shows you the letters at true size before you order, so you can see the margins for yourself. Sizes and dimensions for every plate we make are in UK number plate sizes explained.