The Speed-Distance-Time Triangle

Speed = distance ÷ time · Distance = speed × time · Time = distance ÷ speed. Cover the one you want in the classic triangle and the arrangement of the other two gives the formula.

Average Speed Reality Check

Motorway journeys rarely average the speed limit. Real-world door-to-door averages: motorway-dominated trips ~50–55mph, mixed A-road journeys ~35–40mph, urban driving ~15–20mph. Add 10–20% to calculated times for realistic planning.

Handy Conversions

1 mph = 1.609 km/h. 60mph = 1 mile per minute — the quickest mental maths for journey estimates. A marathon (26.2 miles) at a 10-minute-mile pace takes 4 hours 22 minutes.

Frequently Asked Questions

How do I calculate journey time?

Divide distance by average speed. 120 miles at 60mph takes 2 hours. Add 10–20% for realistic door-to-door planning.

What is the formula triangle?

Distance sits on top; speed and time below. Cover what you want to find and the layout of the remaining two gives the formula.

What is a realistic average speed for planning?

Motorway trips average 50–55mph door to door, mixed A-roads 35–40mph and urban driving 15–20mph.