The decimeter, unit of length
The decimeter is exactly ten centimeters, a tenth of a meter. Almost nobody measures anything in decimeters, and yet the unit carries the definition of the liter, which is a cubic decimeter.
For sixty-three years that last sentence was false. In 1901 the third General Conference on Weights and Measures defined the liter as the volume of one kilogram of pure water at its densest, which turned out to be 1.000028 cubic decimeters rather than one: water refused to cooperate to the last decimal. Chemists carried that discrepancy through their glassware until the twelfth Conference abolished the definition in 1964 and made the liter a cubic decimeter again, exactly. The error was twenty-eight parts per million, invisible in a kitchen and ruinous in a laboratory.
The decimeter in other units
| 1 dm | 0.0001 km |
| 1 dm | 0.1 m |
| 1 dm | 10 cm |
| 1 dm | 100 mm |
| 1 dm | 0.0000621371 mi |
| 1 dm | 0.109361 yd |
| 1 dm | 0.328084 ft |
| 1 dm | 3.93701 in |
| 1 dm | 0.0000539957 nmi |
| 1 dm | 100,000 µm |
| 1 dm | 0.0546807 ftm |
| 1 dm | 0.33 shaku |
| 1 dm | 3.3 sun |
| 1 dm | 0.055 ken |
| 1 dm | 0.000025463 ri |
Frequently asked questions
How many centimeters are in a decimeter?
Ten exactly, and a decimeter is a tenth of a meter. The unit sits between two that everyone uses and is itself used by almost nobody, which is why it survives mainly inside the definition of the liter.
Is a cubic decimeter really a liter?
Yes, exactly, and it has been since 1964. Before that the liter was defined from a kilogram of water and came to 1.000028 cubic decimeters, so the two words did not describe the same volume.
Where is the decimeter actually used?
In school geometry, in a few fabric and timber trades, and in the square decimeter used for surface treatments and platings. Everywhere else the centimeter or the meter takes its place, and the ladder skips a rung.