Number Plate Design Rules UK: What Is and Isn’t Legal (2026)
Quick Answer
UK number plate design is strictly governed by BS AU 145e, covering font, character sizing, colours, permitted backgrounds, and flag or badge identifiers.
Every number plate on UK roads must follow a strict set of design rules defined by BS AU 145e. Get the design wrong and your plate can fail an MOT, attract a £1,000 fine, or cause ANPR cameras to misread your registration. This guide covers exactly what is and is not permitted on a UK number plate.
The Core Rules: BS AU 145e
BS AU 145e is the British Standard governing number plate design. Updated in September 2021, it defines:
- Font: Charles Wright 2001 — the only permitted typeface
- Character height: 79mm (cars); 64mm (motorcycles)
- Character width: 50mm (except 1 and I)
- Stroke width: 14mm
- Spacing within groups: 11mm
- Spacing between groups: 33mm
- Margins: 11mm minimum on all sides
- Colours: Black characters on white (front) and yellow (rear) retroreflective background only
What Flags and Identifiers Are Permitted?
Since 2021, the following national identifiers are permitted on the left-hand side of a number plate:
- GB — the national identifier alone, without a flag
- UK — the new post-Brexit identifier (valid since September 2021)
- England flag (Cross of St George) — with “ENG” identifier
- Scotland flag (Saltire) — with “SCO” identifier
- Wales flag (Red Dragon) — with “CYM” identifier
- Union Jack (GB flag) — with “GB” or “UK” identifier
If your plate displays any of these national identifiers, you do not need a separate GB sticker when driving in most European countries. However, always check the specific rules for your destination country.
What Design Elements Are Illegal?
The following are illegal on road-legal UK number plates:
- Any font other than Charles Wright 2001 — including italic, bold, or custom fonts
- Character spacing that differs from the standard — spacing characters to make them “read” as a word is illegal
- Tinted covers or tinted backgrounds — banned by the 2021 update to BS AU 145e
- Coloured characters — all characters must be black on white/yellow
- 3D characters that obscure the registration — though 3D and 4D plates are legal, characters that are indistinct or too tall are not
- Decorative patterns or images in the plate face — no backgrounds, images, or patterns are permitted
- Flags other than the permitted list — Irish tricolour, EU flag (as a sole identifier), or any other national flag is not permitted
Are 3D and 4D Number Plates Legal?
Yes. The 2021 update to BS AU 145e explicitly legalised raised character plates, including 3D Gel, 4D Laser-Cut, and 4D Gel plates. The characters must still use the correct Charles Wright 2001 font and correct dimensions. All plates sold by Car Plates Pro are fully BS AU 145e certified and road legal.
Borders and Frames
A simple border (single line) around the plate face is permitted. The border must not obscure any part of the registration. Decorative frames with patterns, logos, or text are not permitted on road-legal plates.
Frequently Asked Questions
Can I put my name or logo on my number plate?
No. The only text permitted on the plate face is the registration number, the optional national identifier/flag, the supplier’s details (name and postcode), and the BS AU 145e mark. No personal names, logos, or other text is allowed on a road-legal plate.
Can I change the font on my number plate?
No. Charles Wright 2001 is the only legal font for road-legal UK number plates. Using any other font — including stylised or italic versions — makes the plate non-compliant and results in MOT failure and potential fines.
Are gel number plates road legal?
Yes. 3D Gel plates are fully road legal under BS AU 145e 2021. The gel dome over each character does not affect compliance provided the character dimensions and font are correct. All Car Plates Pro gel plates are BS AU 145e certified.
What is the fine for illegal number plates?
Displaying a number plate that does not meet BS AU 145e is a criminal offence with a fine of up to £1,000. Non-compliant plates will also fail the annual MOT. ANPR cameras may also misread illegal plates, creating additional problems.