Korean numbers 1 to 100: Sino and native, with a converter

Korean has two complete sets of numbers and the counter word decides which one you use. Sino-Korean (일, 이, 삼) goes with money, dates, months, minutes and seconds, phone numbers, floors, and anything from 100 up. Native Korean (하나, 둘, 셋) goes with counting things and people, age in years, and the hours on a clock.

Four native numbers change shape when a counter follows: 하나 becomes 한, 둘 becomes 두, 셋 becomes 세, 넷 becomes 네, and 스물 (20) becomes 스무. So 한 개 (one thing), 두 명 (two people), 세 시 (three o'clock), 스무 살 (twenty years old). The change also applies inside bigger numbers: 스물한 살 (21 years old). Thirty and up do not change: 서른 살.

Hours are native and minutes are Sino, in the same phrase: 세 시 삼십 분 is 3:30. Age is native with 살 (스무 살), but a formal age with 세 is Sino (이십 세). Dates are all Sino: 이천이십오 년 삼월 일 일, 1 March 2025.

Above 99 only Sino-Korean is used, and the places are 백 (100), 천 (1,000) and 만 (10,000). There is no separate word for a hundred thousand: it is ten 만, 십만. So 999,999 is 구십구만 구천구백구십구, ninety-nine 만 and 9,999. One of a place takes no 일: 백, not 일백, and 만 on its own is 10,000. Zero is 영 in arithmetic and 공 when reading out a phone number.