Convert Inches to Decimetres
1 inch is 0.25 dm. One inch is exactly 0.254 decimetres.
One inch is 0.254 decimetres. To convert inches to decimetres, multiply by 0.254; to go the other way, divide by 0.254 or multiply by 3.9370079. The factor is exact rather than rounded: it follows from NIST. Exactly 25.4 millimeters since the 1959 international yard and pound agreement, and one twelfth of a foot.
Factor checked against the defining standard · How we check
- Inches × 0.254
1 * 0.2540.254 dm
1 inch in every length unit
| Unit | Value | Exact factor |
|---|---|---|
| inches (as entered) | 1 in | — |
| feet | 0.08333333333 ft | × 0.0833333333333 |
| yards | 0.02777777778 yd | × 0.0277777777778 |
| miles | 0.00001578282828 mi | × 0.0000157828282828 |
| millimeters | 25.4 mm | × 25.4 |
| decimetres | 0.254 dm | × 0.254 |
| centimeters | 2.54 cm | × 2.54 |
| meters | 0.0254 m | × 0.0254 |
| kilometers | 0.0000254 km | × 0.0000254 |
| nautical miles | 0.00001371490281 nmi | × 0.0000137149028078 |
| micrometers | 25,400 µm | × 25,400 |
| nanometers | 25,400,000 nm | × 25,400,000 |
| thou | 1,000 thou | × 1,000 |
Factors are entered by hand from NIST rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert inches to decimetres? The converter and the working
- 1.Take the measurement in inches.
- 2.Multiply by 0.254 — that is how many decimetres fit in one inch.
- 3.To go back the other way, divide by 0.254, or multiply by 3.9370079.
Worked example: 25 inches to decimetres
- Formula
- in × 0.254 = dm
- Arithmetic
- 25 × 0.254 = 6.35 dm
- Answer
- 25 in = 6.35 dm
The factor is exact, so this figure is exact too — only the display is rounded.
Inches to decimetres conversion table
| Inches | Decimetres |
|---|---|
| 1 in | 0.25 dm |
| 2 in | 0.51 dm |
| 3 in | 0.76 dm |
| 4 in | 1.02 dm |
| 5 in | 1.27 dm |
| 6 in | 1.52 dm |
| 7 in | 1.78 dm |
| 8 in | 2.03 dm |
| 9 in | 2.29 dm |
| 10 in | 2.54 dm |
| 12 in | 3.05 dm |
| 15 in | 3.81 dm |
| 20 in | 5.08 dm |
| 25 in | 6.35 dm |
| 50 in | 12.7 dm |
| 100 in | 25.4 dm |
| 200 in | 50.8 dm |
| 300 in | 76.2 dm |
| 500 in | 127 dm |
| 1000 in | 254 dm |
| 2000 in | 508 dm |
| 5000 in | 1,270 dm |
| 10000 in | 2,540 dm |
What is an inch?
Exactly 25.4 millimeters since the 1959 international yard and pound agreement, and one twelfth of a foot.
What is a decimetre?
A tenth of a metre. Rare in speech and unavoidable in definitions: the litre is a cubic decimetre, which is where the millilitre and the cubic centimetre meet.
How many decimetres are in an inch?
One inch is 0.254 decimetres, exactly. Going the other way, one decimetre is 3.9370079 inches. 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 an inch.
Source: NIST — international yard and pound agreement (inch = 25.4 mm exactly)
Cite this page
- APA
- Rule Calculator. (2026). Convert Inches to decimetres. Rule Calculator. https://rulecalculators.com/convert/inch-to-decimeter
- MLA
- "Convert Inches to decimetres." Rule Calculator, August 16, 2026, https://rulecalculators.com/convert/inch-to-decimeter.
- Chicago
- Rule Calculator. "Convert Inches to decimetres." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/convert/inch-to-decimeter.
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 decimetres are in an inch?
- 0.254. A tenth of a metre. Rare in speech and unavoidable in definitions: the litre is a cubic decimetre, which is where the millilitre and the cubic centimetre meet.
- How do I convert decimetres back to inches?
- Divide by 0.254, or multiply by 3.9370079 — they are the same operation.
Other length conversions
Decimetres to inches — the same conversion the other way.