What is the speed distance time formula?

The three formulas are: Speed = Distance / Time, Distance = Speed x Time, and Time = Distance / Speed. These are all rearrangements of the same relationship. Enter any two values and the calculator solves for the third.

How do I convert between mph and kph?

To convert mph to kph, multiply by 1.60934. To convert kph to mph, divide by 1.60934 (or multiply by 0.62137). For example, 60 mph = 96.6 kph, and 100 kph = 62.1 mph.

What is a realistic average speed for UK roads?

Typical average speeds in the UK are: motorway 55-65 mph, A-road dual carriageway 45-55 mph, single carriageway A/B roads 30-45 mph, and urban areas 15-25 mph. These are significantly lower than speed limits due to traffic, junctions, and varying conditions.

How does average speed differ from top speed?

Average speed is the total distance divided by total time, including stops, slowdowns, and traffic. Top speed is the maximum speed reached. Average speeds are always much lower — for example, a car capable of 120 mph might average only 50 mph on a typical UK journey.

What are UK speed limits?

UK national speed limits are: 70 mph on motorways and dual carriageways, 60 mph on single carriageway roads, 30 mph in built-up areas (some areas have 20 mph limits). These apply to cars and motorcycles; lower limits apply to larger vehicles and those towing.

CarCalcs

Speed Distance Time Calculator — Solve Any Variable

Calculate any one of speed, distance, or time from the other two values.

Solve For

Speed

Distance

How We Calculate This

The Three Formulas

Speed = Distance / Time
Distance = Speed x Time
Time = Distance / Speed

Units

This calculator works in miles and mph (with km and kph conversions shown). Time is in hours and minutes. Make sure your speed and distance use consistent units.

Frequently Asked Questions

Related Calculators

Journey Time Calculator

Calculate estimated journey time from distance and average speed.

Average Speed Calculator

Calculate average speed from multiple journey segments.

Rest Stop Calculator

Calculate recommended rest stops for long journeys based on Highway Code guidelines.

Motorway Fuel Calculator

Calculate fuel needed for motorway journeys with higher consumption rates.

Carbon Footprint Calculator

Calculate the CO2 emissions from your car journey.

Last updated: February 2026

All calculations are estimates. Actual figures may vary based on driving conditions, vehicle specifications, and other factors.