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Korean TTS: Native vs Sino-Korean Numbers and Loanwords

In a Korean script, the same digit can be read two ways. Hours and counted people or things use native Korean numbers (세 시, 스무 명), while dates, money, minutes and measurements use Sino-Korean numbers (시월 십사 일, 만 오천 원). The safest fix for any text-to-speech voice is to write the number out in Hangul exactly as you want it spoken, and to spell loanwords and acronyms the way Koreans say them. For the voices themselves, see Korean text to speech.

Why digits are a problem in Korean scripts

A digit on its own does not tell a reader which number system to use. A native speaker picks one from the counter word that follows, and sometimes from meaning alone. A speech model has to make the same guess, and a wrong guess sounds like a beginner reading aloud.

The clearest example is 3번. As 삼 번 it means "number three", as in 3번 출구 (exit 3). As 세 번 it means "three times". Both are written 3번, and only the sentence tells you which one is meant. If you write the Hangul yourself, nothing is left to guess.

The two number systems

Sino-Korean numbers come from Chinese: 일, 이, 삼, 사, 오, 육, 칠, 팔, 구, 십, then 백 (100), 천 (1,000), 만 (10,000) and 억 (100 million).

Native Korean numbers are 하나, 둘, 셋, 넷, 다섯, 여섯, 일곱, 여덟, 아홉, 열, with tens like 스물 (20), 서른 (30) and 마흔 (40). They are used up to 99. Above that, Sino-Korean takes over even with counters that normally take native numbers, so 100명 is 백 명.

Before a counter, five native numbers shorten: 하나 becomes 한, 둘 becomes 두, 셋 becomes 세, 넷 becomes 네, and 스물 becomes 스무. That is why it is 한 개, 두 잔, 스무 살, but 스물한 살.

Which system goes where

Native Korean numbers

  • Hours: 3시 → 세 시, 12시 → 열두 시
  • Duration in hours: 1시간 → 한 시간
  • People: 5명 → 다섯 명, 20명 → 스무 명
  • Things and animals: 2개 → 두 개, 고양이 3마리 → 고양이 세 마리
  • Cups, bottles, books: 커피 1잔 → 커피 한 잔, 책 4권 → 책 네 권
  • Age in everyday speech: 25살 → 스물다섯 살
  • Times (repetitions): 3번 → 세 번

Sino-Korean numbers

  • Minutes and seconds: 30분 → 삼십 분
  • Dates: 10월 14일 → 시월 십사 일. Note the two irregular months: 6월 is 유월 and 10월 is 시월.
  • Years: 2026년 → 이천이십육 년
  • Money: 15,000원 → 만 오천 원. Korean groups large numbers in units of 만, so 10,000 is 만 and 1,000,000 is 백만.
  • Floors, rooms, numbered items: 3층 → 삼 층, 3번 출구 → 삼 번 출구
  • Measurements and temperature: 5km → 오 킬로미터, 영하 5도 → 영하 오 도
  • Phone numbers: read digit by digit, with 0 as 공: 010 → 공일공
  • Formal age with 세: 25세 → 이십오 세

A full time mixes both systems: 3시 30분 is 세 시 삼십 분, and 2시간 30분 is 두 시간 삼십 분.

How to write numbers in your script

You do not have to convert every digit. Start with the ones where a wrong reading would matter: prices, times, ages, counts, dates in a headline. Then:

  1. Write the number in Hangul with a space before the counter: 세 시, 스무 명, 만 오천 원.
  2. Generate a short test containing those sentences before you produce the whole script.
  3. Listen for the system, not only the digit. A price read with native numbers or an hour read as 삼 시 is the error to catch.
  4. Keep the format consistent across the script, so a course or series does not switch between 3시 and 세 시 from one episode to the next.

Phone numbers, codes and model numbers are worth writing out too. A long string of digits can be read as one large number when you wanted it digit by digit.

Loanwords and English words

Short loanwords and brand names are fine in a Korean script, but writing them in Hangul, the way Koreans actually say them, gives the most predictable result. Use the standard Korean spelling rather than the English original:

  • coffee → 커피, bus → 버스, app → 앱, Wi-Fi → 와이파이
  • YouTube → 유튜브, Netflix → 넷플릭스, iPhone → 아이폰

Acronyms split into two groups. Most are read letter by letter, so write the letters: KTX → 케이티엑스, USB → 유에스비, AI → 에이아이, PDF → 피디에프. Some are said as a word, so write the word: NASA → 나사, UNESCO → 유네스코. If your audience says an acronym a particular way, spell that version.

Units and symbols follow the same rule. km → 킬로미터, kg → 킬로그램, % → 퍼센트. Writing the unit out avoids the voice spelling the symbol or skipping it.

What you can leave alone

Write ordinary Hangul for Korean words. The voices apply standard pronunciation rules on their own, so a word like 국물 is said as 궁물 without you doing anything. Spelling it phonetically would make it worse. The only things worth rewriting are the ones a native reader would also have to stop and think about: digits, symbols, acronyms and foreign words.

Commas and full stops still control the breath. A long sentence with several numbers in it is easier to follow, and easier to check, when split in two.

Testing with each voice

Voxmint has three Korean voices, all in standard Seoul Korean: Minjun, a formal news anchor; Jiwoo, a bright voice for ads and assistants; and Hyejin, a slow, soothing narrator. Run your number test with the voice you plan to use. A price list for Jiwoo or a list of dates in a Minjun bulletin is exactly the kind of passage to check before you generate the full script.

FAQ

Should I write numbers as digits or in Hangul?

For anything that matters, write it in Hangul. Then generate a short test and listen, rather than relying on the voice to pick the right number system.

Why is 20명 written 스무 명 and not 스물 명?

Before a counter, 스물 shortens to 스무. The same happens with 한, 두, 세 and 네. From 21 the full form returns, as in 스물한 명.

Are ages native or Sino-Korean?

Both. Everyday speech uses native numbers with 살 (스물다섯 살). Formal writing uses Sino-Korean with 세 (이십오 세). Write the one that matches your register.

How do I make an English acronym sound right?

Write it in Hangul the way it is said: 유에스비 for USB, 나사 for NASA. Generate a test line to confirm it.

Do I need to spell Korean words phonetically?

No. Sound changes like 국물 → 궁물 are applied for you. Only digits, symbols and foreign words need rewriting.

Write your next Korean script with the numbers spelled out, then hear it with Korean text to speech.