Speed calculations in the United Kingdom
In the UK, road speed limits and vehicle speedometers are legally measured in miles per hour (mph), and distances on British roads are signed in miles and yards.
The equation remains v = d / t, where entering distance in miles and time in hours and minutes yields speed in mph.
For marathon and middle-distance runners in the UK, training paces are routinely quoted in minutes per mile as well as minutes per kilometre.
Worked example: London to Birmingham trip
A journey of 120 miles along the M1 and M6 completed in 2 hours and 24 minutes (2.4 hours) gives:
Average speed = 120 miles ÷ 2.4 h = 50.0 mph.
The vehicle pace is 1 minute 12 seconds per mile.
Inputs for the UK speed calculator
Distance in miles
Enter distance in statute miles as shown on UK road signs.
Duration
Enter hours and minutes taken to complete the trip.
CALCULATOR QUESTIONS
UK road speed & journey time calculator questions
What is the national speed limit on UK dual carriageways?
The national speed limit for cars and motorcycles on UK dual carriageways and motorways is 70 mph, unless signs indicate otherwise.
How do you calculate average speed on UK average speed camera zones?
Average speed cameras record your entry and exit times across a measured distance. Average speed is calculated as distance between cameras divided by elapsed travel time.