km
By unit of length and distance and conversion ,we can say that SI basic unit of length is meters.
I believe that it will be meter. SI unit goes by 10's. what is the sI unit for lengthThe basic SI unit of length is meter.the basic si unit of lenght is metric.The SI base unit for length is meter. For temperature, the SI base unit is kelvin.
Meter Standard meter is the bar of an alloy of platinum and iridium kept under controlled conditions at the " International Sureau of Weights and Measures" near paris.
meter (metre)
By unit of length and distance and conversion ,we can say that the SI unit of length is km .