Best Secondary Schools in Bangkok

Bangkok's secondary market is the deepest in mainland Southeast Asia. Around fifteen schools run an externally credible Year 7 to 13 phase, with another dozen offering a senior phase at lower fee points.

The shape is British IGCSE and A-Level dominance, an IB Diploma top tier built on Patana and NIST, an American flagship in ISB, and a rare-for-SEA cluster of UK-school boarding houses. Geography concentrates the top tier along the Sukhumvit corridor (15, 77, 105), the riverfront (Khlong San), and the Nichada Thani enclave in Pakkret.

The decision at 11 to 18 is different from primary. Exit qualification, university counselling depth, subject breadth at A-Level or HL, and the head-of-sixth-form bench all start to matter. Brand on the gate matters less.

The top tier

Schools that combine externally verified senior outcomes, full Year 7 to 13 provision, and a multi-decade university destinations record.

Bangkok Patana School

Sukhumvit 105 (Bang Na). Ages 2 to 18. 2,300 pupils, the largest single-campus international school in Thailand. CIS re-accredited 2022, FOBISIA founding member. Head: Chris Sammons. Founded 1957.

Patana runs the English National Curriculum to Year 11 with IGCSE, then switches to the IB Diploma at sixth form. It is the canonical Bangkok hybrid: British structure through 16, IB breadth at 16 to 18. The 2023 IB cohort averaged 37 points with a 99% pass rate. IGCSE 2023: *66% A\/A. Top-year fee THB 975,000**.

Shrewsbury International School Bangkok

Riverside (Khlong San) for senior years; City (Rama III) for younger years. Ages 2 to 18. ~2,000 pupils. CIS, FOBISIA. Head: Robert Millar. Founded 2003.

Shrewsbury is the senior school of the Bangkok British market and the first Bangkok campus to deliver the full English independent model from EYFS to A-Level with no IB switch at sixth form. *2025: 74% A\/A at IGCSE, 65.2% A\/A at A-Level, 89.4% A/B at AS. University destinations skew Russell Group with a strong UK / US / Hong Kong split. Riverside carries small senior boarding. Top-year fee THB 1,208,400*.

NIST International School

Sukhumvit 15, Watthana. Ages 3 to 18. 1,800 pupils. Full IB continuum. CIS, NEASC. Head: James Dalziel. Founded 1992 under UN auspices.

NIST is the strongest pure-IB school in Bangkok and one of the strongest in Asia. 2025 IB DP: 110 diplomas, two perfect 45s, 28% scoring 40+ (world average 9%), 100% pass (world average 81%). Central location, walkable from BTS, the rarest geography of any top-tier Bangkok school. Top-year fee THB 1,094,500.

International School Bangkok

Nichada Thani, Pakkret. Ages 3 to 18. ~1,800 pupils. WASC and CIS. Head: Debi Caskey. Founded 1951.

ISB is the oldest international school in Thailand and the city's American flagship. Uniquely in Bangkok it runs the IB Diploma and AP courses in parallel at high school, letting families pick the structured Diploma or a flexible AP portfolio for US-bound applicants. 2023 IB DP average 34 points. Nichada Thani is a self-contained school-and-housing village across the river from central Bangkok. Top-year fee THB 1,162,000.

Harrow International School Bangkok

Sai Noi, north Bangkok (relocated 2021). Ages 2 to 18. ~1,900 pupils. BSO accredited 2023, FOBISIA since 2001. Head: James Murphy-O'Connor. Founded 1998.

Harrow Bangkok was the first Harrow campus outside the UK. The 2021 move to a 90-acre Sai Noi campus bought space for full-size pitches, athletics track, a lake and a real boarding house at the cost of a longer commute. 2020 headlines: *68% A\/A at A-Level, 67% A\/A at IGCSE. Pastoral system follows the Harrow house model. Boarding is a genuine programme from Year 7 upwards and one of the few realistic UK-style boarding options in the city. Top-year fee THB 1,037,100*.

Strong mid-tier

King's College International School Bangkok

Ratchada (Huai Khwang). Ages 2 to 18. BSO Outstanding 2024. FOBISIA since 2021. Head: Sarah Raffray. Founded 2018.

King's Bangkok posts the highest grade headlines in Bangkok: *90% A\/A at A-Level and 98% A\/A at IGCSE (2023). Cohorts are still small; the BSO Outstanding inspection is the more durable signal. Top-year fee THB 1,063,000*.

Wellington College International School Bangkok

Krungthep Kreetha. Ages 2 to 18. COBIS Patron's, CIS, FOBISIA. 1,500 pupils. Head: Chris Nicholls. Founded 2019.

Wellington Bangkok follows ENC to A-Level. *2025 IGCSE: 70% A\-A pass rate. Senior phase still building. Top-year fee THB 1,240,137**.

Brighton College Bangkok

Two campuses: Krungthep Kreetha (senior) and Vibhavadi (Chatuchak). Ages 2 to 18. BSO; KK adds CIS. Heads: Nick Gallop (KK), Crispian Waterman (Vibhavadi). Senior phases opened 2025 from earlier pre-prep starts. *80% A\-B at A-Level** off small early cohorts.

Bangkok Prep

Sukhumvit 77 (On Nut). Ages 2 to 18. CIS and NEASC dual-accredited. 1,700 pupils. Head: Duncan Stonehouse. Founded 2003.

Bangkok Prep is the largest homegrown British senior and the closest A-Level alternative to Patana at a meaningfully lower fee. *2025: 92% A\-C and 58% A\/A at IGCSE; 72% A\-B and 52% A\/A at A-Level. Adds BTEC and the Extended Project Qualification. Top-year fee THB 821,100*.

Concordian International School

Samut Prakan. Ages 2 to 18. Full IB continuum. CIS, NEASC. ~900 pupils. Head: Laurent Goetschmann. Founded 2001.

Concordian is Bangkok's trilingual IB option (English, Mandarin, Thai), with an IB DP 2024 average of 36 points. The trilingual model is unusual at this fee level. Top-year fee THB 963,400.

The Regent's International School Bangkok

Regent's in Wang Thonglang runs British curriculum to IGCSE and IB Diploma at sixth form, with day and boarding for around 800 pupils. Acquired by Nord Anglia Education in August 2025. Long IB DP track record, historically among the better Thailand performers.

Bromsgrove International School Thailand

Don Mueang. Ages 2 to 18. CIS, EDT Gold. ~500 pupils. Head: Giles Montier. Founded 2002.

Bromsgrove is the smaller UK-brand option in the north. 2025: 100% pass rates at both IGCSE and A-Level. Year groups kept deliberately small. Boarding is a long-running programme from Year 7, with houses at both ends of the senior school. Top-year fee THB 743,700.

St Andrews International School Bangkok

Sukhumvit 107 (Phra Khanong). Ages 2 to 18. ~2,300 pupils. Nord Anglia. Head: Paul Schofield. Founded 2013.

St Andrews runs IGCSE and the IB Diploma. *2025: 96% IB DP pass rate, 34.4 average, 90% IGCSE A\-C. Top-year fee THB 849,100**.

Denla British School

DBS in Nonthaburi runs ENC to A-Level. *2024 IGCSE: 59% A\/A; AS Level: 59% A, 72% A-B.** A bilingual English-Thai stream sits alongside the international stream.

Best for A-Levels

The Bangkok schools running a continuous English National Curriculum pathway to A-Level without switching to IB.

• Shrewsbury Riverside. the canonical Bangkok A-Level school. *65% A\/A at A-Level 2025**.
• Harrow. *68% A\/A at A-Level 2020**, house system through Upper Sixth.
• King's College Bangkok. *90% A\/A at A-Level 2023**, BSO Outstanding 2024.
• Wellington College. senior phase maturing.
• Brighton College KK and Vibhavadi. senior years rolling out from 2025.
• Bangkok Prep. *52% A\/A at A-Level**, with BTEC and EPQ on the side.
• Bromsgrove. 100% A-Level pass rate 2025.

Background: A-Levels explained, IGCSE explained.

Best for IB DP

Bangkok schools running the IB Diploma Programme, ranked by latest published average.

• NIST. 2025: 28% above 40 points, 100% pass, two 45s.
• Bangkok Patana. 2023 average 37 points, 99% pass.
• Concordian. 2024 average 36 points, trilingual.
• KIS Reignwood Park. 2024 average 35 points, Pathum Thani.
• St Andrews. 2025 average 34.4, 96% pass.
• ISB. 2023 average 34 points, alongside an AP track.
• Ruamrudee. 97% pass, 34 average, with AP electives.

Patana, Regent's and St Andrews combine British IGCSE earlier with IB DP at sixth form; NIST, ISB, Concordian, KIS and RIS run the IB as the headline senior pathway.

Background: What is the IB Diploma?, IB vs A-Levels.

Best for boarding

UK-school boarding is unusual in Southeast Asia. Bangkok runs against the regional pattern: five international schools have established boarding houses, with two more on the way.

• Harrow Bangkok (Sai Noi). the deepest boarding programme in the city. Harrow house model from Year 7 through Upper Sixth.
• Bromsgrove (Don Mueang). full and weekly boarding from Year 7.
• Regent's (Wang Thonglang). day and boarding for around 800 pupils.
• Shrewsbury Riverside. small senior-year boarding complementing the day school.
• Wells (On Nut). smaller boarding presence at an American-curriculum school.
• KIS Reignwood Park (Pathum Thani). Bangkok's first full IB day-and-boarding campus, opened 2024 on 60 acres.

Wycombe Abbey International School Bangkok is due to open August 2026 on the former VERSO campus near Suvarnabhumi as a British boarding school. Not yet operational.

Three reasons the boarding cluster exists in Bangkok and not in most of Southeast Asia. Harrow arrived in 1998, Bromsgrove in 2002 and Shrewsbury in 2003, and built boarding houses from the start. Regional families from China, Vietnam, Myanmar, Cambodia and Laos use Bangkok boarding as a near-shore UK alternative. Land economics: north and east Bangkok still have space for 60-to-90-acre campuses that Singapore and Hong Kong do not.

At a glance

Fees are 2025-26 published top-year figures in Thai Baht. THB ~32 to USD 1 at indicative 2026 rates. Verify current figures with each school.

Four shapes of senior school

The label hides four quite different shapes of senior school.

Continuous British (Year 7 to 13). English National Curriculum, Cambridge IGCSE or Pearson Edexcel International GCSE at 16, then A-Levels at 18. No curriculum switch at sixth form. Shrewsbury, Harrow, King's, Wellington, Brighton, Bangkok Prep, Bromsgrove and DBS sit here.

British to IB hybrid. ENC through Year 11 with IGCSEs, then a switch to the IB Diploma at 16. The breadth of IB on top of British KS3-4 grammar. Bangkok Patana, Regent's and St Andrews 107 run this model.

Continuous IB (Grade 6 to 12). Middle Years Programme into Diploma Programme. Six subjects plus the core (Theory of Knowledge, Extended Essay, CAS) at sixth form. NIST, Concordian, KIS Reignwood Park. ISB runs IB DP alongside AP.

American (Grade 6 to 12). US Middle School and High School, AP courses for advanced credit, US-style transcript and GPA. ISB, Berkeley, XCL ASB, ICS, Ruamrudee, VERSO and ASB Green Valley.

Three things follow. Exit qualification defines the pathway, not the curriculum label. A child sitting IGCSEs at Bangkok Prep is on a different track from a child taking IB MYP at NIST or AP electives at ISB. All three reach top universities; switching pathways at 15 or 16 is harder than switching schools at 8. University counselling depth becomes a real differentiator. Patana, Shrewsbury, Harrow, NIST and ISB have decades of institutional relationships with admissions offices in the UK, US, Australia and Asia. Subject breadth narrows with age. IGCSE 8-10 subjects, IB DP six, A-Level three or four. A school's ability to offer the combination a child needs depends on scale.

Background: British vs IB vs American curriculum, IB vs A-Levels.

How to choose between them

Five filters cut the list to a short visit list.

Exit qualification. A-Level only, IB DP only, AP only, hybrid. Pick one of the four shapes above and rule out the rest.

Geography. Bangkok's traffic is the dominant variable. A 45-minute one-way school run is normal; 75 minutes is the upper bound a child can sustain for seven years. Sukhumvit (15, 77, 105), Khlong San riverside, Ratchada, Pakkret-Nichada, Don Mueang and Sai Noi each anchor different schools.

Published outcomes. IGCSE A\/A percentages, A-Level A\/A percentages, IB DP averages and pass rates. The schools that publish are easier to compare than the schools that say "available on request"; that itself is a signal.

External accreditation. BSO, COBIS Patron's, CIS, WASC, NEASC. These carry external inspection. A Cambridge International "registered school" badge does not.

Boarding or not. Six schools carry boarding houses with a senior programme: Harrow, Bromsgrove, Regent's, Shrewsbury Riverside, Wells and KIS Reignwood Park. The rest are day schools.

Related reading

• Best international schools in Bangkok (Bangkok pillar)
• Best British schools in Bangkok
• Best IB schools in Bangkok
• Best American schools in Bangkok
• Best primary schools in Bangkok
• IGCSE explained
• A-Levels explained
• What is the IB Diploma?

FAQs

Which Bangkok secondary school is best for UK universities? Shrewsbury Riverside, Harrow, King's College and Bangkok Prep run continuous A-Level pathways with the deepest UK admissions track record. For IGCSE rigour into the IB Diploma, Patana is the canonical hybrid. Russell Group placements come out of all five each year.

Which Bangkok secondary school is best for US universities? International School Bangkok is the only school running the AP and IB Diploma in parallel, with a WASC-accredited US-compatible transcript. NIST, Patana, Shrewsbury and Harrow also place into US universities through the IB Diploma or A-Level routes; the AP route is most direct at ISB.

Is boarding at a Bangkok international school realistic? Yes, at five established schools. Harrow runs the deepest UK-style boarding programme. Bromsgrove, Regent's, Shrewsbury Riverside, Wells and KIS Reignwood Park all carry boarding houses. Wycombe Abbey opens in 2026 as a sixth option.

Why is there so much UK-school boarding in Bangkok specifically? Three reasons. Harrow, Bromsgrove and Shrewsbury arrived early (1998 to 2003) and built boarding houses from the start. Regional families from China, Vietnam, Myanmar, Cambodia and Laos use Bangkok boarding as a near-shore UK alternative. Land economics: north and east Bangkok still have space for 60-to-90-acre campuses that Singapore and Hong Kong do not.

Can a child switch from a British school to an IB school at 16? Yes. Bangkok Patana, St Andrews and Regent's run this internally. Moving from a continuous A-Level school like Shrewsbury into NIST or ISB at 16 is also possible, but the IGCSE-to-IB transition needs preparation. The academic content is manageable; the assessment style is different.

Which schools publish IB Diploma results? NIST, Patana, Concordian, KIS Reignwood Park, St Andrews and Ruamrudee publish recent IB averages and pass rates. ISB publishes a 2023 figure. Several smaller IB schools do not; ask for the average score, pass rate and score distribution directly, and compare against the world average (around 30 points, 81% pass rate in 2024).

Sources: school websites and 2024-25 published admissions and exam-results pages for Shrewsbury, NIST, Bangkok Patana, Harrow, ISB, King's College Bangkok, Wellington College, Brighton College, Bangkok Prep, Bromsgrove, DBS, Regent's, Concordian, KIS Reignwood Park, St Andrews and Ruamrudee; British Schools Overseas, COBIS, CIS and WASC accreditation registers; FOBISIA membership directory; IB Organization 2024 world statistics for IB DP averages and pass rates; Cambridge International and Pearson Edexcel international results 2025 summaries.