The world is a diverse place, and this diversity extends to the standards of dates, phone numbers, PO box numbers, and more used in different countries. South Korea is no exception, as it has its own unique set of formats and rules that can sometimes be a head-scratcher for outsiders.

Back in 2021, my adventure into the world of coding involved tackling the intricate and specific Korean rules governing user input fields using regular expressions. I encountered a myriad of challenges along the way, but ultimately, my persistent efforts and ability to find solutions yielded positive results, and I emerged from the experience with a newfound appreciation for the power of Regex. This post is a result of that journey, and I hope it will provide valuable insights for anyone looking to navigate the complex terrain of Korean regex expressions.

As a result, I've created a list of common regex expressions. This list is by no means an exhaustive collection as there are plenty of patterns to match in Korea.

Use this regex tester to play with expressions, and feel free to comment in the section below.

Birthdate

A Typical Korean date format: YYMMDD. We need to match the year, then the month, and lastly - the day.

/^[0-9]{2}(0[1-9]|1[0-2])(0[1-9]|[1,2][0-9]|3[0,1])$/

Korean Resident Registration Number

The first 6 digits are a birthdate, the 7th digit indicates the gender. Even numbers - female, odd - male.
We allow matching only the following numbers: 0, 1, 2, 3, 4, and 9 because the rest of the numbers are used to identify foreign residents. The 8th - 11th digits designate birthplace & community center, 12th digit - is used to distinguish persons having the same birth date and place of birth.
The last digit stands for a checksum calculation performed on the other digits.

/^[0-9]{2}(0[1-9]|1[0-2])(0[1-9]|[1,2][0-9]|3[0,1])-[0-4,9][0-9]{6}$/

Foreigner Alien Registration Number

The 7th digit should only accept 5, 6, 7, 8 where even numbers - female, odd - male.

/^[0-9]{2}(0[1-9]|1[0-2])(0[1-9]|[1,2][0-9]|3[0,1])-[5678][0-9]{6}$/

Cell Phone Number

A common format is xxx-xxxx-xxxx. Most of the numbers start with 010, but we want to match all possible cases 010, 011, 016, 017, 018, 019.

/^01([0|1|6|7|8|9])-([0-9]{3,4})-([0-9]{4})$/

Telephone number

The first two-three digits represent area codes.

/^(0(2|3[1-3]|4[1-4]|5[1-5]|6[1-4]))-(\d{3,4})-(\d{4})$/

PO Box Numbers

The old format consists of six digits where the 1st digit stands for the metropolitan city, or province, 2nd digit - region, and 3rd digit - municipality/district/borough. The last 3 digits - town, county division, and area.

The new format has five digits where the first two digits - are area codes, 3rd digit - town, county, or autonomous region, and the last 2 digits are serial numbers.

Old /^[1-7]\d{2}-\d{3}$/
New /^(?:0[1-9]|[1-5][0-9]|6[0-3])-\d{3}$/

Korean Driver’s License

/^\d{2}-\d{2}-\d{6}-\d{2}$/

Korean Passport Number

The number has 9 digits in total. The first digit contains the letters M or S, and the remaining digits are serial numbers.

/^[mM|sS]\d{8}$/

Bank Account Numbers

Government-run Banks

KDB /^[0-9]{3}-[0-9]{4}-[0-9]{4}-[0-9]{3}$/
IBK /^[0-9]{3}-[0-9]{6}-[0-9]{2}-[0-9]{3}$/
Nonghyup /^[0-9]{3}-[0-9]{4}-[0-9]{4}-[0-9]{2}$/

Nationwide Banks

Citi /^[0-9]{3}-[0-9]{6}-[0-9]{3}$/
KEB /^[0-9]{3}-[0-9]{6}-[0-9]{5}$/
Kookmin /^[0-9]{6}-[0-9]{2}-[0-9]{6}$/
Shinhan /^[0-9]{3}-[0-9]{3}-[0-9]{6}$/
Woori /^[0-9]{4}-[0-9]{3}-[0-9]{6}$/
SC /^[0-9]{3}-[0-9]{2}-[0-9]{6}$/

Local Banks

Daegu /^[0-9]{3}-[0-9]{2}-[0-9]{6}-[0-9]$/
Busan /^[0-9]{3}-[0-9]{4}-[0-9]{4}-[0-9]{2}$/
Kwangju /^[0-9]{3}-[0-9]{3}-[0-9]{6}$/
Jeonbuk /^[0-9]{3}-[0-9]{2}-[0-9]{7}$/
Jeju /^[0-9]{2}-[0-9]{2}-[0-9]{6}$/

Internet Banks

Kbank /^[0-9]{3}-[0-9]{3}-[0-9]{6}$/
Kakao /^[0-9]{4}-[0-9]{2}-[0-9]{7}$/
Toss /^[0-9]{4}-[0-9]{4}-[0-9]{4}$/

Business Registration Number

The first three digits belong to a specific tax office, two digits in the middle - and the type of business, the rest are serial numbers and a checksum calculation.

/^[0-9]{3}[-]+[0-9]{2}[-]+[0-9]{5}$/

Vehicle License Plate Number

The license plate number contains 2-3 digits, followed by a combination of two Korean characters and 4 digits at the end.
Meaning of Korean characters: general vehicles(가-마, 거-저, 고-조, 구-주), taxi, buses(아, 바, 사, 자), rental cars(하, 허, 호), delivery vehicles(배)

/^\d{2,3}[가-힣]{1}\d{4}$/

Area Codes Table

Area (English)	Area (Korea)	Code
Seoul	서울특별시	02
Gyeonggi	경기도	031
Incheon	인천광역시	032
Gangwon	강원도	033
Chungnam	충청남도	041
Daejeon	대전광역시	042
Chungbuk	충청북도	043
Sejong	세종특별자치시	044
Busan	부산광역시	051
Ulsan	울산광역시	052
Daegu	대구광역시	053
Gyeongsangbuk	경상북도	054
Gyeongnam	경상남도	055
Jeollanam	전라남도	061
Gwangju	광주광역시	062
Jeonbuk	전라북도	063
Jeju	제주특별자치도	064

Postal Codes By Area

Area (English)	Area (Korean)	Codes (range)
Seoul	서울	01 - 09
Gyeonggi	경기	10 - 20
Incheon	인천	21 - 23
Gangwon	강원	24 - 26
Chungbuk	충북	27 - 29
Sejong	세종	30
Chungnam	충남	31 - 33
Daejeon	대전	34 - 35
Gyeongbuk	경북	36 - 40
Daegu	대구	41 - 43
Ulsan	울산	44 - 45
Busan	부산	46 - 49
Gyeongnam	경남	50 - 53
Jeonbuk	전북	54 - 56
Jeonnam	전남	57 - 60
Gwangju	광주	61 - 62
Jeju	제주	63

The 7th digit of Resident Registration Number

Digit	Year Range	Gender
9	1800-1899	male
0	1800-1899	female
1	1900-1999	male
2	1900-1999	female
3	2000-present	male
4	2000-present	female
5	1900-1999	foreign male
6	1900-1999	foreign female
7	2000-present	foreign male
8	2000-present	foreign female

Korean Regex Hacks: Validating Numbers, Addresses and more