Seoul International School
Key Stats
Annual Fees: US$21K - US$31K
Curriculum: American · AP
Age Range: 3-18
Students: ~800
Location: Other Seoul, Seoul
Updated April 2026
In Brief
SIS is the right call for academically ambitious families on the American track who are willing to base themselves in or near Seongnam. The AP results are exceptional and the 53-year track record is real. If location is your primary constraint and you need central Seoul, look at YISS or KIS instead.
Seoul International School was founded in 1973, making it the oldest secular private international school in South Korea. It sits in Seongnam-si in Gyeonggi-do - technically outside Seoul proper, about 30 kilometres south of the city centre - and operates across a full PreK3 through Grade 12 range on a well-established suburban campus. Around 800 students enrol annually across more than 50 nationalities. The school runs an American curriculum with no IB component, but with 23 Advanced Placement courses it offers the deepest AP programme of any international school in the Seoul metropolitan area.
The academic results are the defining feature. In 2025, SIS students sat 629 AP exams across 23 subjects; 48% scored 5 (the maximum) and a further 33% scored 4. Those numbers are extraordinary even by the standards of Seoul's competitive international school market. The AP Capstone programme - a research-intensive qualification sitting above standard APs - saw 31% of the 2024 graduating class earn the Capstone Diploma, which requires high scores across both AP Research and AP Seminar. CEOWorld Magazine ranked SIS 15th among the world's best international high schools in 2024. The school holds WASC accreditation and is a member of EARCOS and ECIS.
Fees for 2026-27 combine a Korean Won tuition base with a USD component, reflecting the school's mixed billing structure. PreK3 comes to roughly KRW 27.9M all-in; by Grades 9-12, the total reaches KRW 41.1M - placing the high school years at a cost comparable with SFS. The USD portion is substantial (USD 6,720 for PK3 rising to USD 9,900 for high school), so families paying out of pocket should model exchange-rate scenarios. Class sizes are capped at 23 for most year groups. The Seongnam location is the main practical consideration: families based in Gangnam have a manageable drive, but those in Mapo, Yongsan, or north Seoul face a 45-60 minute commute each way.
What parents value
- –Strongest AP programme in the Seoul area: 23 courses, 48% of exams scored 5 in 2025, 33% scored 4. The AP Capstone Diploma adds a research credential with genuine university recognition.
- –Oldest secular private international school in South Korea, founded 1973. Over 50 years of WASC accreditation and a university placement track record that most newer schools cannot match.
- –Ranked 15th globally among international high schools (CEOWorld 2024). For families prioritising high school university outcomes, SIS is the strongest American-track option in the Seoul metro area.
Points of consideration
- –Seongnam location adds significant daily travel for families in central or north Seoul. Model the commute from your home address before committing - many families relocate to Bundang or southern Gangnam to make it manageable.
- –Fees reach KRW 41.1M for high school after the USD component is converted at current rates. The large USD portion (USD 9,900 for Grades 9-12) makes total cost exchange-rate sensitive - calculate both at current rates and at a 10% KRW depreciation scenario.
- –The school covers the full PreK-12 range but the campus's reputation and draw are primarily in the high school. Families with primary-age children should visit and ask specifically what the junior school experience looks like day-to-day.
Annual Fees
| Year Group | Age | USDTotal Annual Fee |
|---|---|---|
| Pre-Kindergarten 3 (PK3) | 3 | 18,536 |
| Junior / Senior Kindergarten (JK/SK) | 4 | 22,199 |
| Grades 1-5 | 6 | 22,460 |
| Grades 6-8 (Middle School) | 11 | 24,394 |
| Grades 9-12 (High School) | 14 | 27,325 |
Fees converted from KRW. For the most up to date and accurate figures please double check with the school.
Additional Fees
| Fee | Amount |
|---|---|
| Application Fee (non-refundable) | 332 |
| Initial Registration Fee (non-refundable) | 2,659 |
Photos
Academic Results
| AP score 5 rate (2025) | 48% |
| AP score 4 rate (2025) | 33% |
Key results: AP score 5 rate (2025) 48%, AP score 4 rate (2025) 33%.
Extra Curriculars
Contact the school for details on co-curricular activities and facilities. Ask what a normal week looks like outside lessons for your child's age group.
Inspections & Accreditations
Inspection
No published inspection details are currently available.
Accreditations
Accreditation details are not publicly listed.
Memberships
Membership details are not publicly listed.
Student Body
Seoul's international schools serve a diverse mix of diplomatic, corporate, and locally-based families. Contact the school for current enrolment details.
Leadership
School leadership
Contact the school for details.