Number Plate BS AU 145e - 3D and 4D Number Plates

BS AU 145e: The UK Number Plate Standard Explained

BS AU 145e is the mandatory British Standard governing how UK number plates are manufactured, tested, and displayed. Introduced on 1st September 2021 to replace the older BS AU 145d regulation, its primary purpose is to improve vehicle readability for Automatic Number Plate Recognition (ANPR) cameras.

Every UK number plate manufacturer must legally comply with these rules. Because the previous ‘145d’ standard is no longer legally valid, anyone purchasing new registration plates must source them from a registered supplier using fully compliant materials.

Core Technical Requirements of BS AU 145e

The updated standard introduced strict formatting and spacing rules to ensure high visibility and uniform layouts across all UK vehicles.

  • Single-Tone Characters: Registration characters must be solid “piano black” printed in the official Charles Wright font. Two-tone finishes, carbon effects, 3D/4D shadow styling, or split-digit characters are illegal.
  • The 10mm Clear Space Rule: To prevent optical interference for ANPR scanners, a mandatory clear zone of at least 10mm must surround the registration characters. No branding, borders, or graphics may encroach on this area.
  • Required Markings & Dimensions:
    • The Standard Mark: The text “BS AU 145e” must be permanently printed on the bottom right of every plate.
    • Manufacturer Identifiers: The business name and postcode of the supplying outlet must be clearly visible on the bottom edge.
    • Placement: These bottom markings must sit exactly 7mm below the main registration characters and be printed at a height between 3mm and 10mm.
  • Optional Borders & Lips: Peripheral borders are permitted but optional. If used, they must sit at least 10mm away from the characters and have a maximum thickness of 5mm. A raised protective lip around the outer edge of the plate is also allowed.
  • Recommended Fixing Methods: The standard strongly favors using high-strength adhesive pads over self-tapping screws. Piercing the plate surface can introduce moisture, causing delamination and durability issues over time.

The Durability Tests Number Plates Must Pass

While BS AU 145e carried over most of the resilience tests from the old legislation—such as impact, weathering, and solvent resistance, it introduced two rigorous new testing phases:

1. Near-Infrared Contrast Test

Modern ANPR cameras read vehicle registration marks using infrared lighting spectrums rather than visible light. Under BS AU 145e, manufacturers must prove that the contrast ratio between the reflective plate background and the solid black characters remains exceptionally high under infrared wavelengths to ensure instant camera capture.

2. Abrasion Resistance Test

Plates must be tough enough to survive the harsh daily wear of road debris, dirt, salt gritting, and high-pressure jet washing. This test ensures the reflective coatings and digits will not easily erode, scratch, or peel away.

Supply & Manufacturing Compliance

UK number plate manufacturers can choose to self-certify their products by replicating these test conditions in-house, or they can submit their materials to an accredited third-party testing body. Regardless of the chosen path, the legal responsibility for full compliance lies entirely with the manufacturer. For full display requirements, see the official GOV.UK number plate rules.

Sourcing Compliant Number Plate Components

If you are looking for high-quality, fully compliant raw components and digit designs, working with an industry-vetted trade partner ensures your stock stays on the right side of the law. You can explore a complete range of certified trade supplies on the Dash Dynamics number plate products sector page.

For material specifications, bulk ordering details, or trade pricing queries, feel free to reach out directly through the Dash Dynamics contact page to speak with a component expert.