Old units of volume that seem obsolete but are actually common in daily life

Although South Korea currently uses the metric system, old units of measurement are still surprisingly common in daily life.

For example, calculating house size in "pyeong," buying meat by the "geun," or gold by the "don."

Similarly, a unit of measurement that is very commonly seen in daily life is the "doe."

"Isn't that only used when selling grains at traditional markets? How is it common?"

You might think that, but you can often find products in supermarkets and convenience stores that use one "doe."

Specifically, the 1.8-liter PET bottle. One "doe" converts to 1.8 liters.

This is the answer to why the awkward 1.8-liter PET bottle is frequently used, rather than 1.5L, 2L, or even a middle-ground 1.75L.

This is also why 1.8L and 3.6L capacities are most commonly used for seasonings and liquor bottles.

Because people have used terms like "one doe of soy sauce" or "one doe of refined rice wine" for a long time, they simply converted those traditional amounts into liters, resulting in 1.8L.

This is why most products in Western countries are 2L rather than the awkward 1.8L.

Most containers using 1.8L are products from East Asian countries.

Additionally, the smaller unit "hop" (合, 180ml, which is one-tenth of a doe) is also frequently used.

The most common example is the rice measuring cup used for cooking rice, which is exactly one "hop."

Since there was a culture of considering one "hop" as roughly one glass of alcohol, multiples of 180 are often used for alcoholic beverages.

The reason a bottle of soju is 360ml is that two "hops" of soju equal 360ml.

It's the same in Japan, where a bottle of sake is usually 360ml or 720ml.

Source: https://theqoo.net/hot/4226368609