# Sai (a unit of volume in old Japanese system of weights and measures) (才)

Sai is a unit of volume (capacity) in old Japanese system of weights and measures.

When sai is used as a unit for weighing a load of a ship or a building stone, 1 sai is deemed to have the cubic volume of 1 shaku on a side (1 shaku is about 30.3 centimeters). 1 cubic shaku is roughly equal to 0.027826 cubic meters (27.876 liters) in the metric system. In this case, 10 times 1 sai (10 cubic shaku) is called 1 koku (a unit).

When sai is used as a unit for weighing lumber (especially valuable lumber), 1 sai is deemed to have the volume of 1 sun square multiplied by 1 ken length or by 2 ken length in some regions of Japan (1 sun is about 3.03 centimeters, and 1 ken is about 1.8182 meters). Provided 1 ken is equalized with 6 shaku, the volume is about 0.0016696 cubic meters.

Besides, a 10th volume of 1 shaku, or a 1000th of 1 sho, is also called 1 sai. 1 sai here is equal to 10 futsu. In this case, 1 sai is set at 1.8039 milliliter.