Korean units of measurement, called cheokgwan-beop (Korean: 척관법; Hanja: 尺貫法) or cheokgeun-beop (척근법; 尺斤法) in Korean, is the traditional system of measurement used by the people of the Korean peninsula. It is largely based on the Chinese system, with influence from Japanese standards imposed following its annexation of the Korean Empire in 1910. Both North and South Korea currently employ the metric system. Since 2007, South Korea has criminalized the use of Korean units in commercial contexts, but informal use continues, especially of the pyeong as a measure of residential and commercial floorspace. North Korea continues to use the traditional units, although their standards are now derived from metric conversions.

Customary Korean units are a local adaption of the traditional Chinese system, which was adopted at a very early date. They were imposed and adjusted at various times by royal statutes. The details of the system have varied over time and location in Korea's history. Standardization—to the extent it occurred—was accomplished by officially sanctioned rulers, ropes, odometers, triangulation devices, weights, cups, and basins.

Although most of the measures operate on a decimal system, the standard form was to read out the units of each place (as, e.g., 3 cheok, 1 chon, 4 bun, 1 ri) rather than list them as a single number of the largest unit (as 3.141 cheok).

Taejo of Joseon established a Market Bureau (시사; 市司) or Bureau of Weights and Measures (평시서; 平市署) at the foundation of the Joseon dynasty in 1392. The Joseon Kingdom later attempted a standardization of length based on square brass rulers, which were used by magistrates and the secret police to fight commercial fraud. Under the Joseon, different classes of society were permitted different numbers of kan in their homes, but in its traditional sense—like the Japanese ken—of a bay between two pillars rather than as a set unit of length.

The 1496 Great Codex of State Administration (Kyŏngguk Taejŏn) included a section on approved measures and their verification. It employed a li of 360 paces or 2160 feet but did not explicitly mention that conversion until its 1746 supplement.

The 1897 Law on Weights and Measures uniting Korea's various local systems was the first legislation enacted upon the Joseon's establishment of the Korean Empire.

During the Japanese occupation from 1910 to 1945, Japan imposed its standards on Korea. Two of the most common "traditional" units in Korea—the pyeong of floorspace and the jeweler's don—were among those given their modern value by the Japanese.

South Korea signed the Metre Convention in 1959 and notionally adopted the metric system under Park Chung Hee on 10 May 1961, with a strict law banning the use of the Korean pound, li, gwan, and don effective as of 1 January 1964 and—after metric conversion of the land registries—the pyeong. The metrication was not applied to imported or exported goods and remained so generally spotty as to be considered a failure, with the government abandoning its attempts to enforce the statute by 1970. The traditional units feature in many Korean sayings and much of its literature and poetry, including the national anthem, which mentions Korea's "three thousand lis of rivers and mountains". Further attempts to fully metricate occurred in 1983, 2000, and 2001, with publicity campaigns praising the metric system and condemning traditional units through TV and radio ads, brochures, signs, and contests. A common theme was the origin of the present values of the units under Japanese occupation; Yun Byeong-su of the Korea Association of Standards & Testing Organizations noted that "even Japan has forsaken the don for the units of grams and ounces but here we are standing around like idiots still blathering on about don." Nonetheless, strong opposition from the construction and jewelry industries and negative media coverage forced Korean politicians to avoid the topic and regulators to settle for dual use of conventional and metric measures.