40 mph speed limit sign: what it means
The 40 mph sign means the maximum speed on that road is 40 miles per hour. Do not go faster, and slow down further when the road or the weather calls for it.
What does the 40 mph speed limit sign mean?
The red ring makes it an order: 40 mph is the maximum for every vehicle on that road (Rule 124). Repeater signs remind you that the limit continues until a sign shows another one.
A speed limit is a maximum, not a target. rule 125 says it does not mean it is safe to drive at that speed whatever the conditions.
Quick quiz
What does the sign at the top of this page mean?
- Maximum speed 40 mph.
- Maximum speed 30 mph.
- Maximum speed 50 mph.
Show answer
A. Maximum speed 40 mph. A red ring around a number gives the maximum speed in miles per hour (Know your traffic signs). Source: The Highway Code, rule 124, GOV.UK; The Highway Code, rule 125, GOV.UK; The Highway Code, rule 207, GOV.UK; Know your traffic signs: speed limit signs, GOV.UK; Traffic sign images, Department for Transport, GOV.UK
Where will you see it?
On busier main roads through suburbs and on the edge of towns, on some rural roads with bends or junctions, and on approaches to villages, where a higher limit drops before the 30 mph or 20 mph limit.
What should you do?
Keep to 40 mph or less and look out for the next sign. Watch for people crossing, buses pulling out and side roads. rule 207 warns that at 40 mph your vehicle will probably kill any pedestrian it hits.
What do people get wrong?
Speeding up to 40 as soon as you see the sign when the road is busy, wet or dark. The limit is the most you may do; the right speed is often lower.
Common questions
Does a 40 mph sign apply to cars towing a trailer?
Yes. It is the maximum for the road. A vehicle may also have its own lower national limit, and you must keep to whichever is lower (The Highway Code, rule 124).
Why are there small 40 signs along the road?
They are repeater signs. The large sign marks the start of the limit and the smaller ones remind you that it still applies.
Compare with
Want to test someone else? Play a road-sign quiz with friends and family.
Sources
Checked on 3 November 2026 against Know your traffic signs (speed limit signs) and The Highway Code rules 124, 125 and 207.
- The Highway Code, rule 124, GOV.UK
- The Highway Code, rule 125, GOV.UK
- The Highway Code, rule 207, GOV.UK
- Know your traffic signs: speed limit signs, GOV.UK
- Traffic sign images, Department for Transport, GOV.UK
Contains public sector information licensed under the Open Government Licence v3.0. Traffic sign images are Crown copyright, from the Department for Transport. Sources and image credits.