Number plates displayed on vehicles have been required by law in the UK since 1904. The law was passed to assist the authorities when a car was involved in either an accident or crime. To ensure that number plates are always easy to read, there are certain laws that govern them with rules on precisely what format they are presented in.

But what is the law on number plates? If you’ve ever wondered whether tinted plates are legal, if a stylish 4D number plate is legal or how small a registration number can be represented on a motorcycle, we have the answers you seek.

You might be looking to style your vehicle with a set of personalised plates or simply curious about where the law stands when it comes to registration numbers and how they’re displayed. Either way, read on for all there is to know on the UK's laws regarding the unique number plates we all show on our vehicles.

Legal number plates

While the rules for number plates can sometimes seem extensive and complicated, it’s essential that you understand them fully to avoid unfortunate consequences. If you fail to follow the governmental guidelines you could face penalties, including fines of up to a thousand pounds for being caught by the authorities on the road or failing your annual MOT test.

The format for registration plates currently consist of two letters followed by two number and then three letters. The first two characters are the memory tag of the DVLA and show the location of a vehicle’s registration. The two numbers that follow state the vehicle’s age and are taken from a special code, which can pinpoint just when it was registered. The last letters are random and used to identify the vehicle.

A plate that is considered legal will meet all the rules on spacing, size, margin requirement and font. It’ll also adhere to the strict requirements involving patterns and colours to ensure it can be easily read when necessary.

Your front plate must always display your registration in black characters on a white background and your rear plate should also show the characters in black on a yellow field. In the UK it’s perfectly legal to have a flag present on your plate, including the St George’s cross, the Welsh red dragon, the Saltire for Scotland or the Union Jack.

If you opt to display a flag on your number plate, you’re allowed to accompany it with words including England, Scotland, Wales or Cymru and United Kingdom as well as Great Britain; these can be displayed in all capital letters. You can also display the country name as an abbreviation in both lower upper-case combinations along with capitals such as Eng or ENG, Sco or SCO and Cym or CYM.

Plates should always be made of reflective material and never patterned.

The Charles Wright Font is the chosen font seen as standard for UK number plates. If you’re seeking to personalise the way your registration number is displayed, selecting a 3D or 4D design can be a legal way of achieving this.

If you’re able to provide proof of vehicle ownership and your identity, like your V5 registration document and drivers licence, most quality motor factors you’ll find will be able to supply you with registration plates to the legal standard. Large chains like Halfords offer plates made while you wait for affordable prices. It’s also possible to purchase legal pressed number plates from several online companies that specialise in registration plates, but be sure they are registered with the DVLA before placing your order.

The legal number plate size

Here in the United Kingdom, the legal requirements for your number plate involve the size of the characters displayed on your plate rather than the dimensions of the plate itself.

To begin with, all the characters, both letters and numbers displayed on your plate, must be of equal height. For plates that were purchased between the dates of January 1st, 1973 and September 1st, 2001, their characters are legally required to be 89 mm in height. Plates that were bought outside of these dates should have a height of 79 mm.

The stroke width of the characters on your plate should legally be 14mm in width although the letter ‘I’ and number ‘1’ are exceptions to this rule. The width of the characters should always keep to the same rules despite a different thickness of a number or letter. Keep your characters consistent to avoid any fines for an illegal number plate.

Another area of your number plate with a specific rule is the spacing between each character. The rules applying to plates that were registered after September 1st 2001 and prior to January 1st 1973 insist that 11mm must be left between every one of the characters displayed and 33mm between the age identifier and memory tag.

If your number plate was registered during the period between January 1st 1973 and September 1st 2001, the plate characters must have 13mm between one another and have 38mm between the age identifier and memory tag.

There are also rules regarding the margin of your number plate. If you are getting a number plate fitted now, you’ll need to leave a margin of 11mm on all sides of the registration number. Plates that were attached before September 1st 2001 require a margin on all sides of 13mm. Finally, if your plates were fitted in 1972 or any earlier, the same requirement as today stands with margins of 11mm all round.

Are 3D number plates legal?

On the government website, the DVLA clearly state that number plates using 3D materials are legal. This alone doesn’t make them legal; they must follow all the rules for number plates as described by the law. They mustn’t have a background pattern and must display black letters on a white grounding at the front and on a yellow at the rear. They must always be made of reflective material and the characters must adhere to the law regarding size and height.

Are 4D number plates legal?

4D number plates are recent additions for registration. These design formats are often chosen for a premium and personalised appearance. Manufactured from 3mm thick characters in black acrylic, they’re attached to acrylic plates using extremely strong adhesive. As the DVLA has stated that number plates can be 3D, number plates that are 4D are also legal on the road when designed to British Standard BS AU 145d, using the Charles Wright Font.

Are small motorcycle number plates legal?

For aesthetic reasons, many motorcyclists are looking for the smallest plate possible to put on their bike to streamline its look. This is often influenced by the way motorcycles are sold, with the number plates advertised often far smaller than the kind normally seen in use.

In the United Kingdom, there aren’t laws that dictate the size of your motorcycle’s number plate but there are specifications for the size of the characters presented on it. While most standard cars in the UK must use a number plate with characters of 50mm in width by 79 mm in height, motorcycles can remain within the laws of the road with characters of 44mm in width and 64mm in height.

Are gel number plates legal?

Gel number plates are most commonly associated with 3D style registrations can be manufactured to British Safety Standard BS AU 145d making them legal for use on UK roads.
In a 3D gel number plate, the registration digits are raised from the plate, crafted from a polyurethane resin of high quality.

Are sticker number plates legal?

Whether stick-on number plates can be used legally is a common topic for those taking part in car forums. Once used on a variety of vehicles, notably old e-type Jaguars, new laws insist that number plates adhere to certain laws to avoid fines on the road or risk failing their MOT.

According to the law, number plates must be manufactured from reflective material and must be marked with the official British Safety Standard. These are two areas that stick-on plates often fail on.

To pass its MOT, there are stipulations regarding a car’s number plate strength too. This can be another area in which number plates in sticker format, compared to solid acrylic plates, have been known to fail.

Are tinted number plates legal?

The DVLA states that number plates shouldn’t be obscured in any way, which means if you have tinted number plates, you could be considered breaking the law.

The increase in the use of 3D and 4D plates in recent years has created a grey area on the topic as this style of lettering is not hampered by tinting to the plate. Due to the nature of this design style, the numbers and letters on the registration plate don’t become less visible and continue to be fully legible. For the most part, to stay inside the law, tinted style number plates should only be used for show plates and not for use on the road.