General
Distance Calculator
Works distance from speed and time, where the speed has to be the average.
Result
Assumes a constant speed for the whole period. Real journeys with stops cover less ground than this in the same elapsed time.
Get a Free Business AuditHow the calculation works
Speed multiplied by time, with consistent units. The speed used has to be the average over the whole period rather than a typical or maximum speed, since multiplying a cruising speed by total elapsed time overstates the distance by whatever the stops and slow sections removed.
What moves the number
- Average speed over the whole period.
- Unit consistency between speed and time.
- Whether the time is elapsed or moving.
- Route distance against straight-line distance.
Where this one goes wrong
Using a cruising speed against elapsed time is the standard error in journey planning, because it ignores every stop, junction and slow section, and the resulting estimate is reliably optimistic. Use an average that includes them. Route distance is the other distinction, since straight-line distance between two points is shorter than any road between them, sometimes considerably in hilly or built-up terrain.
Before you quote
- Use an average speed that includes stops and slow sections.
- Keep speed and time units consistent.
- Use route distance rather than straight-line distance.
Questions
About this calculator
Why is my journey estimate always optimistic?
Because a cruising speed multiplied by elapsed time ignores stops, junctions and slow sections. Using an average speed that includes them produces a realistic figure, and the gap is larger on shorter journeys.
Is straight-line distance useful?
For some purposes and not for travel. Any road between two points is longer than the straight line, sometimes considerably in hilly or built-up terrain, which is why route distance is what a journey calculation needs.
What units should be used?
Consistent ones. Miles per hour times hours gives miles; miles per hour times minutes gives nothing useful without dividing by sixty. The result's units follow the inputs, so the conversion has to be deliberate.
The formula
distance = speed × time
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How to use this calculator
- Speed. Enter your own figure; the page starts at 55.
- Unit. Enter your own figure; the page starts at Miles per hour.
- Time: hours. Enter your own figure; the page starts at 1.
- Time: minutes. Enter your own figure; the page starts at 45.
The result updates as you type, so you can try a figure, see what it does to distance covered, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Speed | 55 |
| Unit | Miles per hour |
| Time: hours | 1 |
| Time: minutes | 45 |
What comes out
| Result | Value |
|---|---|
| Distance covered main result | 96.25 |
| In the other unit | 154.8994 |
| Round trip | 192.5 |
| Time in decimal hours | 1.75 |
At 55 mph for 1.75 hours you cover 96.25 miles: 192.5 there and back.
How sensitive the answer is
Holding everything else steady and changing only speed, this is what happens to distance covered. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Speed | Distance covered |
|---|---|
| 27.5 | 48.125 |
| 41.25 | 72.1875 |
| 55 example above | 96.25 |
| 82.5 | 144.375 |
| 110 | 192.5 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Speed
- A number, starting at 55.
- Unit
- Choose from Miles per hour, Kilometres per hour.
- Time: hours
- A number, between 0 and 10000, starting at 1.
- Time: minutes
- A number, between 0 and 59, starting at 45.
What the results tell you
| Result | What it is |
|---|---|
| Distance covered | The headline result. A number. |
| In the other unit | A number. |
| Round trip | A number. |
| Time in decimal hours | A number. |
Keep going
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