The 20-metre number plate rule: where it comes from and how it is enforced

Every UK learner meets the number plate check at the start of the practical car test, but few people see where the rule is written down. In Great Britain (England, Scotland and Wales) it appears in regulations made under the Road Traffic Act 1988 and in the DVSA test procedure. Northern Ireland has its own licensing system run by the Driver and Vehicle Agency (DVA), and its guidance describes the same distances with a slightly different procedure. This guide follows the published texts only.

What the Great Britain regulations say

The Motor Vehicles (Driving Licences) Regulations 1999 set the standard for Group 1 licences, which cover ordinary car and motorcycle entitlement. Regulation 72 includes a visual acuity standard with two limbs: a visual acuity of at least 6/12 (decimal 0.5), and the ability to read in good daylight a registration mark on a motor vehicle with characters of the prescribed size, in each case with corrective lenses if necessary. For most vehicles the prescribed size is characters 79 millimetres high and 50 millimetres wide, viewed from 20 metres. A separate visual field standard sits in the same regulation, and the site’s UK page summarises all three parts of the UK standard.

So the plate is not only a test-day hurdle. It is part of the licensing standard that applies to applicants and to existing licence holders in Great Britain.

Why there are two distances

Schedule 8 of the same regulations sets out what a candidate must do in the practical test for categories B and B+E (cars) and for motorcycle categories. The eyesight element allows either of two readings, in good daylight and with corrective lenses if worn:

• a registration mark with letters and figures 79 mm high and 57 mm wide, read at 20.5 metres
• a registration mark with letters and figures 79 mm high and 50 mm wide, read at 20 metres

GOV.UK describes the practical result: 20 metres for a vehicle with a new-style plate (two letters followed by two numbers) and 20.5 metres for an old-style plate.

What happens at the test in Great Britain

GOV.UK states that at the start of the practical test the candidate must correctly read a number plate on a parked vehicle. A candidate who cannot read it fails and the test does not continue. DVLA is told and the licence is revoked. When the person reapplies, DVLA asks for an eyesight test with the DVSA at a driving test centre, and the standard DVSA eyesight test must still be passed at the next practical test.

Roadside checks and the offence

Section 96 of the Road Traffic Act 1988, which applies in England, Wales and Scotland, makes it an offence to drive a motor vehicle on a road while eyesight is such that a person cannot meet a prescribed requirement, whether the defect is uncorrected or insufficiently corrected. A constable who has reason to suspect this may require the driver to take a test, using no other means of correction than the driver used at the time of driving. Refusing is a separate offence.

Schedule 2 to the Road Traffic Offenders Act 1988 lists the offence as summary only, punishable by a fine at level 3 on the standard scale, with discretionary disqualification and obligatory endorsement. GOV.UK summarises the position by saying a driver could be prosecuted for driving without meeting the standards of vision for driving.

What the DVA says in Northern Ireland

nidirect describes the same distances. The examiner asks the candidate to read a number plate on a stationary vehicle with letters and figures 79 mm high and 57 mm wide at 20.5 metres, or at 20 metres if they are 50 mm wide. If the candidate cannot read it, the examiner asks for a second plate. If that also fails, the examiner measures the exact distance from a third plate. A candidate who fails the third and is judged unable to meet the requirement ends the test, and is asked to sign a declaration that the requirement was not met. The legal wording in Northern Ireland comes from its own legislation, so the GB regulation references above should not be applied there.

Using the practice tools

The rule is about a real plate at a real distance. The step-back number plate practice and the approaching car number plate game help candidates become familiar with plates at roughly the right size, and the Vision Arcade offers more practice games. They are practice aids and cannot confirm that anyone meets the legal standard. Anyone with doubts should see an optician.

Frequently asked questions

Does the 20-metre rule apply to motorcycle tests too?

Yes. Schedule 8 sets the same two plate readings for motorcycle categories A and P as for cars.

Is the plate read with glasses?

Yes, with the aid of corrective lenses if worn. GOV.UK says glasses or contact lenses must be worn every time you drive if they are needed to meet the standards, and nidirect adds that they must stay on throughout the test.

The bottom line

The 20-metre check traces to the Group 1 licensing standard and to Schedule 8 of the 1999 regulations in Great Britain, with distances of 20 metres for 50 mm-wide characters and 20.5 metres for 57 mm-wide characters. It can also be enforced at the roadside under section 96. Northern Ireland applies the same distances through DVA procedure. This is general information, not legal or medical advice.

Sources

• Driving eyesight rules (gov.uk)
• The Motor Vehicles (Driving Licences) Regulations 1999, regulation 72 (legislation.gov.uk)
• The Motor Vehicles (Driving Licences) Regulations 1999, Schedule 8 (legislation.gov.uk)
• Road Traffic Act 1988, section 96 (legislation.gov.uk)
• Road Traffic Offenders Act 1988, Schedule 2 (legislation.gov.uk)
• Driving eyesight requirements (nidirect.gov.uk)