Road Legal Number Plates: The Complete UK Rules (2026)
Short answer: road legal number plates in the UK must be made from reflective material, with black characters on white at the front and yellow at the back, in the Charles Wright font, at the standard size and spacing, with no background pattern. Plates fitted since 1 September 2021 must also show the supplier’s name and postcode and the British Standard mark “BS AU 145e”. Get any of that wrong and you risk a fine of up to £1,000 and an MOT fail.
Here’s every rule in one place, in plain English, from a DVLA-registered supplier that makes road-legal plates every day in Hounslow.
Written by the PlateBoss team, led by owner HD. We’ve been making plates since 2019 and are a DVLA-registered number plate supplier with a workshop in Hounslow, west London. Updated and checked against DVLA and GOV.UK guidance, September 2026. How we write our guides.
In this guide
- The road legal number plates checklist
- Font, size and spacing
- BS AU 145e and markings
- 3D, 4D and gel plates
- Flags, identifiers and the green flash
- Motorbikes and trailers
- Private plates and spacing
- Penalties
- Buying from a registered supplier
- FAQs
The road legal number plates checklist
| Rule | What’s required |
|---|---|
| Material | Reflective |
| Colours | Black characters on white (front) and yellow (rear) |
| Background | No pattern |
| Font | Charles Wright |
| Characters | A single shade of black, not removable or reflective |
| Markings (fitted since 1 Sept 2021) | Supplier’s name and postcode, and BS AU 145e |
| Raised characters | Allowed (3D gel, 4D) if all of the above is met |
| Front and rear | Both required on cars; rear only on motorbikes registered from 1 September 2001 |
Font, character size and spacing
For cars and most vehicles:
- Characters are 79mm tall and 50mm wide (except the number 1 and the letter I), with a 14mm stroke.
- 11mm between characters, and 33mm between the age identifier and the random letters.
- 11mm margins at the top, bottom and sides. On two-line plates, 19mm between the lines.
Italic, script or “sporty” fonts aren’t allowed, and neither is moving the spacing.
BS AU 145e and the supplier’s markings
BS AU 145e is the British Standard that came in on 1 September 2021. It made plates tougher and more consistent, and it banned characters in more than one shade of black. Every plate fitted since then must show the supplier’s name and postcode and “BS AU 145e”, usually along the bottom edge. If those are missing, the plate isn’t road legal, however it looks.
Want plates that tick every box? Every plate we make is BS AU 145e, in the legal font and spacing, with our supplier details on it. Standard pairs from £29.99.
Order road-legal platesAsk us on WhatsAppAre 3D, 4D and gel plates road legal?
Yes. GOV.UK says plates “can also have 3D (raised) characters”. That covers 3D gel, 4D laser-cut and 4D gel plates, as long as the letters are solid, single-shade black and the plate meets everything else above. We’ve gone into detail in are 4D plates legal? and 3D vs 4D number plates.
Flags, national identifiers and the green flash
- Allowed flags: the Union flag, Cross of St George, Cross of St Andrew or Red Dragon of Wales.
- Allowed identifiers include UK, GB, ENG, SCO, CYM and WALES (or the full names).
- The flag goes above the identifier, on the left of the plate. Neither can be more than 50mm wide or sit in the margin.
- Zero-emission vehicles can display a green flash on the left of the plate. See our EV number plates.
Motorbikes and trailers
Motorbikes and motor tricycles registered on or after 1 September 2001 only show a rear plate. Their characters are smaller: 64mm tall, 44mm wide, a 10mm stroke, 10mm between characters and 30mm between the groups. For the full breakdown, including why most bike plates are 9 x 7 inches, see our guide to motorbike number plate size. Trailers must show the same registration as the car towing them. We make both: motorbike plates and trailer plates.
Private plates and spacing
You can’t rearrange or misrepresent the characters to spell a name or word. The DVLA says a registration that’s misrepresented may be permanently withdrawn, and you won’t get your money back. If the reg doesn’t naturally spell what you want, the spacing still has to stay legal.
Penalties for plates that aren’t road legal
- A fine of up to £1,000 for incorrectly displayed number plates.
- An MOT fail. See can a number plate fail an MOT? for what testers check.
- For private regs, the risk of the registration being withdrawn.
Buying road legal number plates from a registered supplier
Only a DVLA-registered number plate supplier can legally make road-legal plates, and they must see your ID and proof you’re entitled to the reg. Here’s what documents you’ll need. If a seller doesn’t ask, they’re probably selling show plates.
Once your plates arrive, our guides on how to install number plates and how to clean number plates will keep them legal for years.
Road legal number plates
Replacement Number Plates
£29.99
3D Gel Number Plates
£49.99
4D 3mm Number Plates
£49.99
4D 3mm Gel Number Plates
£64.99Need road legal plates? Order before 2pm for same-day dispatch with free tracked delivery, or collect from our Hounslow workshop.
Shop road-legal platesCollect in HounslowWhatsApp usRoad legal number plates: FAQs
What makes a number plate road legal in the UK?
Reflective material, black characters on white (front) or yellow (rear), the Charles Wright font at the legal size and spacing, no background pattern, and, for plates fitted since 1 September 2021, the supplier’s name, postcode and BS AU 145e mark.
What is BS AU 145e?
The current British Standard for number plates, which came in on 1 September 2021. Plates fitted since then must be marked with it.
Are 3D and 4D plates road legal?
Yes, raised characters are allowed if they’re a single shade of solid black and the plate meets BS AU 145e.
What’s the fine for illegal number plates?
Up to £1,000, and the car will fail its MOT.
Can I have a flag on my number plate?
Yes: the Union flag, Cross of St George, Cross of St Andrew or Red Dragon of Wales, with an approved identifier, on the left of the plate and no more than 50mm wide.
Do motorbikes need a front number plate?
No. Motorbikes registered on or after 1 September 2001 only display a rear plate.
