📐 Shaku & Sun Length Converter (尺・寸)

The Shaku & Sun Length Converter converts the traditional Japanese foot (shaku, 尺) and inch (sun, 寸) into modern units. The shaku is the base unit of the shakkanho length system.

1 shaku = 10 sun in both systems. The kane-jaku is the standard legal definition (10/33 m). The kujira-jaku is 1.25 times longer, used only for traditional textile measurement (kimono, obi, fabric).

The shaku influences modern Japanese life: the standard tatami mat (Edoma) is 6 shaku x 3 shaku. The ken (architectural bay) is 6 shaku. Height is sometimes described in shaku (e.g. "7-shaku shelf" = 2.12 m).

Conversion formulas:

Key conversions (kane-jaku):

• 1 shaku = 30.303 cm = 11.93 inches
• 1 sun = 3.0303 cm = 1.193 inches
• 1 shaku = 0.994 feet (very close to 1 foot)
• 1 ken = 6 shaku = 1.818 m

The kane-jaku shaku (30.3 cm) is close to the English foot (30.48 cm), differing by only 0.6%. This similarity sometimes causes confusion in international contexts.

For architectural bay spacing (6 shaku), see our ken converter. For general length conversions, use the length converter. Room area combines well with the tatami area calculator.

1. Enter the length in shaku (尺) or sun (寸).
2. Select the standard: kane-jaku or kujira-jaku.
3. Select the target unit (cm, inch, m).
4. Click Convert to see the result.

How many cm is one shaku?

One kane-jaku shaku equals 10/33 m = 30.303 cm. The kujira-jaku shaku (used for traditional tailoring) is 37.879 cm. Unless otherwise specified, "shaku" refers to kane-jaku.

Is a shaku the same as a foot?

Nearly. The kane-jaku shaku (30.303 cm) is 0.58% shorter than the English foot (30.48 cm). They are close but NOT identical. For precise work, always use the correct unit. This similarity helped historical trade between Japan and Western nations.

What is the difference between kane-jaku and kujira-jaku?

Kane-jaku (曲尺, metal ruler) = 30.303 cm, used for architecture and general measurement. Kujira-jaku (鯨尺, whale ruler) = 37.879 cm (1.25x kane-jaku), used exclusively for traditional textile and kimono measurements. The kujira-jaku rulers were historically made from whale baleen.

How many sun are in one shaku?

One shaku = 10 sun in both systems. The sun (寸) is the sub-unit of shaku, analogous to the inch in the imperial system. 1 sun (kane-jaku) = 3.0303 cm.

How is the shaku related to the ken?

One ken (間, architectural bay) = 6 shaku = 1.818 m. The ken is the fundamental module of traditional Japanese architecture, and it is defined in terms of the shaku. Room dimensions are typically measured in ken or multiples of shaku.

Kane-jaku vs kujira-jaku. Architecture and general measurement use kane-jaku (30.3 cm). Traditional tailoring (kimono fabric) uses kujira-jaku (37.9 cm), which is 1.25 times longer. Always confirm which system is referenced when reading dimensions.

Tatami dimensions. A standard Edoma tatami mat is 6 shaku x 3 shaku (180 cm x 90 cm = 1.62 m2). This makes shaku the natural unit for carpentry related to tatami rooms.

Height measurements. Some older Japanese buildings list ceiling height in shaku. "8-shaku ceiling" = 2.42 m. Modern ceilings are typically 2.4-2.7 m (7.9-8.9 shaku).

The shaku vs English foot. The kane-jaku shaku (30.303 cm) is very close to the English foot (30.48 cm), differing by only 0.58%. This coincidence made trade easier during the Meiji opening. However, they are NOT identical - precision work requires using the correct unit.