ConverterHub

Ri to Kilometer Converter

Enter a distance and choose a direction to convert between ri and kilometers.

How it is calculated

The conversion uses one fixed factor, 3.927 kilometres per ri. Ri to kilometres: km = ri × 3.927. Kilometres to ri: ri = km / 3.927. Which formula is applied depends on the direction selector (ri to km is the default). The result is rounded to three decimals, a second line states the factor (1 ri = 3.927 km, or 1 km = 0.255 ri when going the other way), and a third line converts the answer back to your original unit as a check.

The value must be greater than zero; zero and negative numbers give no result. The factor is the one for the traditional Japanese ri, not the Chinese li and not any rounded 4 km figure, so a sum done with 4 km per ri will differ by about 2 %. The tool does not convert to miles or metres, so do a second step for those units.

Worked example

An old travel record gives a distance of 12 ri. With the direction on ri to km: 12 × 3.927 = 47.124 km. The rate line reads 1 ri = 3.927 km, and the check line converts back, 47.124 / 3.927 = 12.000 ri. In the opposite direction, 50 km divided by 3.927 gives 12.732 ri, so a 50 km road is a little under 13 ri of the old measure.

Try this example →

Common mistakes

  • Leaving the direction on ri to km when you typed kilometres. 50 km would then be multiplied by 3.927 and shown as 196.350 km instead of being converted to ri.
  • Mixing up the ri with the Chinese li. They are different units, and the factor here applies only to the Japanese ri.
  • Using a rough 4 km per ri in the head. The exact factor is 3.927, so for a 12 ri journey the rough figure gives 48 km instead of 47.124 km.
  • Entering zero or a negative distance. The tool requires a positive value and returns nothing otherwise.
  • Treating the three-decimal result as a surveyed distance. The old ri was a travel-distance unit, so a historical figure converted here is an approximation of the real distance.

About this calculator

The ri was a traditional Japanese unit of distance, standardized during the Edo period as 36 chō, which fixes it at exactly 1 ri = 3.927 kilometers — noticeably longer than the Chinese li it’s historically related to. It was the standard unit for measuring road and travel distances between towns before Japan adopted the metric system.

Historians, translators, and readers of classical Japanese literature and old maps still encounter ri as a distance unit and need to convert it to make sense of the actual scale involved. This calculator converts between ri and kilometers in either direction using the 3.927 km conversion factor.

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