What Is Shaku?
Shaku is a traditional Japanese unit used to measure length. It is close to the length of a human forearm. Today, one shaku is a little more than 30 centimeters.
Shaku is not part of the modern metric system, but you still see it in Japan for things like old houses, temple plans, woodwork and some musical instruments.
Definition
In modern terms, one standard shaku is defined as exactly 10 divided by 33 of a meter.
That means:
- 1 shaku is about 0.303 meter
- 1 shaku is about 30.3 centimeters
- 1 shaku is about 11.93 inches
So 1 shaku is a little shorter than 1 foot, because 1 foot is 12 inches.
There is also another type called kujirajaku, used in cloth measuring. That one is longer, about 0.379 meter, but when people say shaku today, they usually mean the standard 0.303 meter length.
History / Origin
The idea of the shaku came to Japan long ago from ancient China. In China there was a unit called chi. Japan adapted this idea and created its own version, the shaku.
Long before meters existed, people used parts of the body to measure length. The shaku was close to the length from the elbow to the fingertips. Carpenters and builders used wooden rulers marked in shaku, sun and bu to build houses, temples and bridges.
In the late 1800s, Japan switched to the metric system. In 1891, the government fixed the shaku to be exactly 10 divided by 33 of a meter. This made the shaku a clear and stable unit, even though meters became the main system for most uses.
Symbol & Abbreviation
The shaku is written with the Japanese character 尺.
Common ways to write it are:
- shaku in plain letters
- 尺 in Japanese text
There is no official short symbol for shaku in the metric or SI systems like m for meter or cm for centimeter.
In old Japanese drawings, you may see marks based on shaku and its smaller parts, such as sun and bu, instead of using letters.
Current Use Around the World
Today, shaku is mostly used in Japan, and only in some special fields. Most daily life uses meters and centimeters.
You may still find shaku in:
- Traditional carpentry builders of temples, shrines and old style wooden houses
- Architecture plans for older buildings drawn in shaku
- Tatami mats where the sizes often relate to shaku based room layouts
- Kimono and cloth work sometimes using the longer kujirajaku
- Traditional music for example some flutes are named and sized using shaku lengths
Outside Japan, the shaku is not used in normal trade. It mainly appears when people study Japanese history, design, or classical building methods.
Example Conversions
Here are some simple conversions between shaku and metric or imperial units. All numbers are rounded to make them easier to remember.
From shaku to meters and centimeters
- 1 shaku ≈ 0.303 m ≈ 30.3 cm
- 3 shaku ≈ 0.909 m ≈ 90.9 cm
- 5 shaku ≈ 1.515 m ≈ 151.5 cm
- 10 shaku ≈ 3.03 m
From shaku to feet and inches
- 1 shaku ≈ 0.994 foot ≈ 11.93 inches
- 3 shaku ≈ 2.98 feet ≈ 35.8 inches
- 6 shaku ≈ 5.97 feet ≈ 71.6 inches
- 10 shaku ≈ 9.94 feet
From meters to shaku
- 1 meter ≈ 3.3 shaku
- 2 meters ≈ 6.6 shaku
- 3 meters ≈ 9.9 shaku (almost 10 shaku)
Quick rule of thumb to change shaku to meters, you can multiply shaku by 0.3 in your head. It is not exact, but it is close and fast.
Related Units
The shaku belongs to a family of old Japanese length units. Some important related units are:
- Sun a smaller unit. 1 shaku = 10 sun
- Bu even smaller. 1 sun = 10 bu, so 1 shaku = 100 bu
- Ken a larger unit used in building spacing. 1 ken is usually 6 shaku
- Jo another larger unit. 1 jo is often 10 shaku
- Meter the main modern length unit. 1 shaku is about 0.303 meter
- Foot a common imperial unit. 1 shaku is almost 1 foot
Knowing how shaku connects to sun, bu, ken and jo helps when reading old Japanese building plans or room sizes.
FAQs
How long is 1 shaku in meters?
One standard shaku is exactly 10 divided by 33 of a meter, which is about 0.303 meter or 30.3 centimeters.
Is shaku the same as a foot?
No. One shaku is very close to one foot, but not exact. 1 shaku is about 11.93 inches, while 1 foot is 12 inches.
What is the difference between shaku and kujirajaku?
Both are Japanese units with the same base word, but they have different lengths and uses. The common shaku is about 30.3 cm and is used in carpentry. Kujirajaku is about 37.9 cm and is often used for cloth measuring.
Is shaku still used in Japan today?
Yes, but only in limited ways. Japan mainly uses meters now. Shaku continues in traditional carpentry, some crafts and music instrument sizes.
Why did Japan keep shaku after adopting meters?
Many classic buildings, tools and skills were based on shaku. Keeping it helps builders and craftsmen match old sizes and follow long standing design rules.
How many shaku are in 1 meter?
One meter is about 3.3 shaku. More exactly, it is 3.3 repeating shaku, but 3.3 is good enough for most quick calculations.
Can I still buy a ruler marked in shaku?
In Japan, you can still find special carpentry rulers marked in shaku, sun and bu. Outside Japan, they are less common and are mainly sold for traditional woodworking.
