Inches to Kilometers
Type a value in either box to convert between inches and kilometers. The factor is 2.54e-05.
| Inches | Kilometers |
|---|---|
| 1 in | 2.54e-05 km |
| 2 in | 5.08e-05 km |
| 3 in | 7.62e-05 km |
| 5 in | 0.000127 km |
| 10 in | 0.000254 km |
| 25 in | 0.000635 km |
| 50 in | 0.00127 km |
| 100 in | 0.00254 km |
How to use
- Enter a value in the Inches field.
- The Kilometers figure appears immediately — no button to press.
- Typing in the Kilometers field converts back to Inches the same way.
- Use the reference table for the values that come up most often.
Inches to Kilometers formula
The factor from inches to kilometers is 2.54e-05.
km = in × 2.54e-05
Why this factor: the inch and the kilometer are both defined against the meter, so dividing one definition by the other gives 2.54e-05 directly. Both definitions are set out in full below.
To go the other way, divide by 2.54e-05 — or use the Kilometers to Inches converter, which is the same calculation reversed.
Worked example
Take 100 in and multiply by the factor 2.54e-05: the result is 0.00254 km.
100 in × 2.54e-05 = 0.00254 km
The converter above does this for any value you type, in either direction.
What is an inch?
An inch is one twelfth of a foot, used for small dimensions and for screen and wheel sizes globally.
Definition: Exactly 25.4 millimeters since the 1959 International Yard and Pound Agreement — an exact, not approximate, relation.
Where it is used: Screen diagonals, pipe and fastener sizes, tire and wheel diameters, and print layout worldwide.
What is a kilometer?
A kilometer is 1,000 meters, the standard unit for road distances and geography in most of the world.
Definition: Exactly 1,000 meters by SI prefix definition — 'kilo' means 10³.
Where it is used: Road signs, running and cycling distances, and map scales outside the US and UK.
Inches vs Kilometers
The inch is an imperial unit while the kilometer is a metric unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many kilometers are in an inch?
One inch equals 2.54e-05 kilometers.
What is the formula to convert inches to kilometers?
Multiply the number of inches by 2.54e-05. To reverse it, divide by 2.54e-05 instead.
How do I convert kilometers back to inches?
Divide by 2.54e-05, which is the same as multiplying by 39370.0787.
How many kilometers are in 10 inches?
10 in works out to 0.000254 km.
How is the inch defined?
Exactly 25.4 millimeters since the 1959 International Yard and Pound Agreement — an exact, not approximate, relation.