Average speed is total distance divided by total time, including stops. Driving faster saves less time than people expect: on a 30-mile trip, going 70 instead of 60 mph saves only about 4 minutes.
How to use the Speed Calculator
- Distance
- Time
- Compare with speed
- Every result field is editable: type into Average speed and Time plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the distance and the time it took. Optionally enter another speed to compare the travel time. Type a speed into the result to find the time.
Tips
- Use your own measured figures – fuel economy, speed and prices vary a lot with driving style, traffic, load and season.
- Pick the unit in each field’s menu (miles or kilometres, mpg or L/100 km); the calculator converts everything for you.
- Fill up to the brim twice and divide the distance by the fuel added to measure real fuel economy.
- For vehicle modifications, treat results as a starting point and confirm with the parts maker or a professional mechanic.
Common mistakes to avoid
- Mixing US and imperial (UK) gallons – a UK gallon is about 20% bigger.
- Using the advertised fuel economy instead of real-world figures.
- Forgetting tolls, parking and wear and tear when comparing driving with public transport.
Inputs explained
| Field | What to enter |
|---|---|
| Distance | Units: mi, km, m, nmi |
| Time | Units: min, h, s |
| Compare with speed | Units: mph, km/h, m/s, knots |
What each result means
- Average speed = [Distance]÷[Time]
- Pace = [Time]÷([Distance]÷1609.344)÷60
- Time at comparison speed = [Distance]÷[Compare with speed]÷60
- Time difference = [Time]÷60 – [Time at comparison speed]
Example values
How the main result changes when Time changes and everything else stays at the example values above:
| Time (min) | Average speed (mph) |
|---|---|
| 15 | 120 |
| 22.5 | 80 |
| 30 | 60 |
| 37.5 | 48 |
| 45 | 40 |
| 60 | 30 |
Formula
Average speed = distance ÷ timeTime at another speed = distance ÷ new speedWorked example
Inputs — Distance: 30 mi; Time: 30 min; Compare with speed: 70 mph.
Results — Average speed = 60 mph; Pace = 1 min/mi; Time at comparison speed = 25.7 min; Time difference = 4.3 min.
Frequently asked questions
How do I calculate average speed?
Divide the total distance by the total time: 30 miles in 30 minutes is 60 mph.
How do I convert mph to km/h?
Multiply by 1.609344.
Does driving faster save much time?
Less than you might think – 10 mph faster on a 30-mile trip saves about 4 minutes but uses noticeably more fuel.
What formula does the Speed Calculator use?
Average speed = distance ÷ time.