What is the required width for characters on a number plate?

The required width for characters on a number plate, specifically for the standard vehicles in the UK including Scotland, is 50mm. This specification is important for ensuring that the characters can be easily read in various conditions, thus aiding law enforcement, automated recognition technology, and other stakeholders in identifying vehicles effectively. The uniformity in size helps maintain consistency across all registration plates, leading to better identification and improved road safety.

Other options do not meet the legal requirements set by the regulations governing the registration and display of vehicle number plates. The dimensions are standardized to not only facilitate readability but also to ensure compliance with the law, making 50mm the correct choice for the width of characters on a number plate.