UK Number Plate Validity Check: Everything You Need to Know

If you drive in the UK, you’ve likely never thought twice about your number plate—until you need a new one or get flagged for a potential issue. Yet, UK number plates are governed by strict legal standards, and failing to follow them can lead to fines, MOT failures, or even vehicle seizures.

This post breaks down everything you need to know about a BS AU 145e compliant UK number plate, so you can stay safe, legal, and confident on the road.

🔍 UK Number Plate Specifications (BS AU 145e)

Under the BS AU 145e standard, number plates must follow precise design rules to ensure they are readable, traceable, and camera-compatible.

Here are the key specifications:

1. Typeface

• The only legal typeface is Charles Wright, the standard font designed specifically for UK number plates to maximize clarity and readability.

2. Character Stroke Width

• All characters must have a stroke width of 14mm, ensuring uniform boldness for visibility from a distance.

3. Spacing

• Character spacing: 11mm between individual letters/numbers.

• Group spacing: 50mm between different character groups (e.g., AB23 and XYZ).

4. Edge Margin

• There must be at least 11mm of space from any character to the edge of the plate.

5. Character Height

• Characters must be 79mm tall.

6. Character Width

• Most characters should be 50mm wide, with exceptions for narrower letters like “I” and “1”.

7. Supplier Details

• Plates must display the supplier's name and postcode, as registered with the DVLA.

8. Legal Marking

• All number plates must include:

  • The BS AU 145e certification

  • The manufacturer's name or trademark

9. Character Colour

• All characters must be black only—no colored or stylized fonts are allowed.

10. Permanent Characters

• 3D and 4D plates are legal only if the characters are non-removable and permanent.

11. Camera Compatibility

• Number plates must be readable by ANPR (Automatic Number Plate Recognition) cameras, using 850nm & 940nm infrared wavelengths.

12. Correct Format

• The plate must match the BS AU 145e format, which has been tested and certified for:

  • Reflectivity

  • Thermal resistance

  • Abrasion and impact resistance

🏁 Permitted Flags & Letters

If you want a national flag or identifier, only the following are allowed:

• Flags: Union Jack, England (St George), Scotland (St Andrew), Wales (Red Dragon)

• Identifiers: GB, UK, ENG, SCO, CYM, WALES

✅ Summary: Quick Compliance Checklist

⚠️ Why It Matters

Driving with an invalid plate can:

• Fail your MOT

• Lead to police stops and fines

• Trigger ANPR system errors

• Make your vehicle appear suspicious or illegal

Always check that any new number plate you purchase is BS AU 145e compliant and made by a DVLA-registered supplier.

📎 Reference

• GOV.UK: Get Vehicle Information from DVLA