Convert Thou to Kilometers
1 thou is 2.54e-8 km. One thou is exactly 2.54e-8 kilometers.
One thou is 2.5400 × 10^-8 kilometers. To convert thou to kilometers, multiply by 2.5400 × 10^-8; to go the other way, divide by 2.5400 × 10^-8 or multiply by 3.9370 × 10^+7. The relation is exact but the figure is not: it is a rounding of a number that does not terminate, and it follows from NIST.
Factor checked against the defining standard · How we check
- Thou × 2.5400 × 10^-8
1 * 2.54e-80 km
1 thou in every length unit
| Unit | Value | Exact factor |
|---|---|---|
| inches | 0.001 in | × 0.001 |
| feet | 0.00008333333333 ft | × 0.0000833333333333 |
| yards | 0.00002777777778 yd | × 0.0000277777777778 |
| miles | 0.00000001578282828 mi | × 0.0000000157828282828 |
| millimeters | 0.0254 mm | × 0.0254 |
| decimetres | 0.000254 dm | × 0.000254 |
| centimeters | 0.00254 cm | × 0.00254 |
| meters | 0.0000254 m | × 0.0000254 |
| kilometers | 0.0000000254 km | × 0.0000000254 |
| nautical miles | 0.00000001371490281 nmi | × 0.0000000137149028078 |
| micrometers | 25.4 µm | × 25.4 |
| nanometers | 25,400 nm | × 25,400 |
| thou (as entered) | 1 thou | — |
Factors are entered by hand from NIST rather than derived from a units library, so the ones that terminate are exact rather than rounded.
The same converter answers this pair however it is written: thou to kilometres is the British spelling of the same units — the metre and the litre are spelled that way outside the United States and the quantity does not change.
How do you convert thou to kilometers? The converter and the working
- 1.Take the measurement in thou.
- 2.Multiply by 2.5400 × 10^-8 — that is how many kilometers fit in one thou.
- 3.To go back the other way, divide by 2.5400 × 10^-8, or multiply by 3.9370 × 10^+7.
Worked example: 25 thou to kilometers
- Formula
- thou × 2.5400 × 10^-8 = km
- Arithmetic
- 25 × 2.5400 × 10^-8 = 6.35e-7 km
- Answer
- 25 thou = 6.35e-7 km
The factor is rounded for display; the figure above is computed from the full value.
Thou to kilometers conversion table
| Thou | Kilometers |
|---|---|
| 1 thou | 2.54e-8 km |
| 2 thou | 5.08e-8 km |
| 3 thou | 7.62e-8 km |
| 4 thou | 1.02e-7 km |
| 5 thou | 1.27e-7 km |
| 6 thou | 1.52e-7 km |
| 7 thou | 1.78e-7 km |
| 8 thou | 2.03e-7 km |
| 9 thou | 2.29e-7 km |
| 10 thou | 2.54e-7 km |
| 12 thou | 3.05e-7 km |
| 15 thou | 3.81e-7 km |
| 20 thou | 5.08e-7 km |
| 25 thou | 6.35e-7 km |
| 50 thou | 0.00000127 km |
| 100 thou | 0.00000254 km |
| 200 thou | 0.00000508 km |
| 300 thou | 0.00000762 km |
| 500 thou | 0.0000127 km |
| 1000 thou | 0.0000254 km |
| 2000 thou | 0.0000508 km |
| 5000 thou | 0.000127 km |
| 10000 thou | 0.000254 km |
What is a thou?
A thousandth of an inch, exactly 25.4 micrometers, and called a mil in American workshops — the same word the metric world uses for a millimeter, which is why a drawing marked "5 mil" is worth checking twice.
What is a kilometer?
One thousand meters, and about 0.621 miles.
How many kilometers are in a thou?
One thou is 2.5400 × 10^-8 kilometers. Going the other way, one kilometer is 3.9370 × 10^+7 thou. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every length unit here
The whole group — 13 units with their symbols and the size of each one in meters — is on the conversion index, along with every pair it makes. The table above already gives each of them relative to a thou.
Source: NIST — international yard and pound agreement (inch = 25.4 mm exactly)
Cite this page
- APA
- Rule Calculator. (2026). Convert Thou to kilometers. Rule Calculator. https://rulecalculators.com/convert/thou-to-kilometer
- MLA
- "Convert Thou to kilometers." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/thou-to-kilometer.
- Chicago
- Rule Calculator. "Convert Thou to kilometers." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/thou-to-kilometer.
The date is when the figures on this page were last checked against their source, not the day you opened it. Add your own access date if your style needs one.
Questions people actually ask
- How many kilometers are in a thou?
- 2.5400 × 10^-8. One thousand meters, and about 0.621 miles.
- How do I convert kilometers back to thou?
- Divide by 2.5400 × 10^-8, or multiply by 3.9370 × 10^+7 — they are the same operation.
Other length conversions
Kilometers to thou — the same conversion the other way.