Japanese Measurements

Something you’ll commonly find here on Wasen Modeler is mention of measurements in traditional Japanese units. I do this as an “Extension Student” of Japanese traditional boatbuilding. The basic unit is the shaku. The Japanese have two different kinds of shaku, one use by taylors and one used by carpenters. What we use here, the one for carpenty, is technically a kanejaku (kah-ney-jah-coo), but is simply called a shaku.

One shaku is almost exactly equal to one foot, but specifically 1 shaku = 11.9 inches. The shaku is divided up into 10 units called sun (soon), each sun is diving into 10 units called bu (Boo), and each bu is divided into 10 rin.

On the larger scale, there are a few units of larger measure, which sometimes appear when you’re researching. They are the Jyō, the Ken, and the Hiro, with 1 Jyō = 10 Shaku, 1 Ken = 6 Shaku, and 1 Hiro = 5 Shaku.

Jyō (丈) = 119″ or 9.92′

Ken (間) = 71.6″ or 5.97′

Hiro (尋) = 59.5″ or 4.96′

Shaku () = 11.9″

Sun (寸) = 1-3/16″

Bu (分) = about 1/8″

Rin () = a bit under 1/64″

For the metric builders out there, a shaku is about 10/33 of a meter or 30.3cm

Jyō (丈) = 3.03m

Ken (間) = 1.818m

Hiro (尋) = 1.515m

Shaku () = 10/33m or 30.3cm

Sun (寸) = 1/33m or 3cm

Bu (分) = 1/330m or 3mm

Rin () = 1/3300m or 0.3mm

The best way to use Japanese units is to simply invest in a Japanese tape measure or square. These are a bit pricey, but very handy, particularly if you can work in 1/10-scale, which is nice, convenient scale for modeling smaller wasen. At this scale, the only conversion necessary, is to move the decimal place over by one digit.

Being in the San Francisco Bay Area, I’m lucky enough to have access to two Japanese hardware stores. For those less fortunate, you can order online from Hida Tools in Berkeley, where I’ve purchased the few Japanese tools I own. You can find them on the web at http://www.hidatool.com.

The one I use is a 5 sun by 10 sun square, but if you click on this link to buy it, just be aware that they posted the wrong photo on their website and show the 2.5 sun by 5 sun square. The smaller squares are certainly much cheaper, and they have the advantage of laying flat – the large square is has a thicker corner for strength. The 2.5 sun by 5 sun square looks nice, and there is a smaller 1.5 sun by 3 sun square that’s only $10.