What Makes a Number Plate Road Legal in the UK?

What Makes a Number Plate Road Legal in the UK?

Introduction

With so many number plate styles available today, it can be confusing to know which ones are actually road legal. Getting it wrong can result in a fine of up to £1,000, a failed MOT, and even points on your licence. Here's everything you need to know about what makes a number plate road legal in the UK.

The British Standard: BS AU 145e

All road legal number plates in the UK must comply with British Standard BS AU 145e. This standard covers everything from the materials used to the size and spacing of characters. Any plate sold by a registered supplier should carry this certification.

Correct Font

Number plates must use the Charles Wright font — a specific typeface designed for maximum readability. You cannot use italic, bold, or decorative fonts. The characters must not be altered in any way that makes them harder to read.

Correct Colours

The rules on colour are strict:

  • Front plate — white background with black characters
  • Rear plate — yellow background with black characters
  • Characters must be black — no coloured, chrome, or tinted characters are permitted

Correct Character Size and Spacing

Characters must be a specific size and spaced correctly. The standard sizes are:

  • Character height: 79mm
  • Character width: 50mm (except the number 1 and letter I)
  • Stroke width: 14mm
  • Space between characters: 11mm
  • Space between groups: 33mm
  • Top, bottom, and side margins: 11mm

Supplier Details

Every road legal number plate must display the following on the plate itself:

  • The name and postcode of the supplying company
  • The BS AU 145e standard mark

No Alterations

You must not alter, rearrange, or obscure any characters on your number plate. This includes adding flags, symbols, or decorative elements that interfere with the registration number.

National Identifiers and Flags

You are permitted to display a national identifier on the left-hand side of your plate. Approved identifiers include:

  • GB (with or without the Union Flag)
  • UK (with or without the Union Flag)
  • England flag (St George's Cross)
  • Scotland flag (St Andrew's Cross)
  • Wales flag (Red Dragon)
  • Green EV badge (for zero-emission vehicles)

At Metal Plates Britain, our pressed metal plates are available with all of these emblems. Browse our full range here.

What About Pressed Metal Plates?

Pressed metal 3D aluminium plates are fully road legal provided they meet all the above requirements. The embossed characters must still conform to the correct font, size, and spacing standards.

Summary

To be road legal, your number plate must use the correct font, colours, character sizes, and carry the BS AU 145e certification and supplier details. Always buy from a registered number plate supplier to ensure your plates are fully compliant.

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