How to Apply to Computer Science at Caltech: A Common First-Year Core, Choosing the CS Option at the End of First Year, and Banded SAT/ACT Review, with Requirements and Timelines for Chinese and Canadian High School Students and Transfer Students

At the California Institute of Technology (Caltech), majors are called “options”. Undergraduate computer science is the Computer Science option in the Computing + Mathematical Sciences (CMS) department, leading to a Bachelor of Science. Here is what you need to know for fall 2027 entry, based on Caltech’s official information, for students at high schools in China, students at Canadian high schools (including BC and Vancouver students), and transfer students.

1. Getting into the CS option

• No major on the application: the admissions site says every first-year student takes the same classes in the first two terms and declares a major at the end of the first year.
• Core: the first-year core underpins all options. CS 1 is an Institute core requirement; you either take it or place out through a placement exam over the summer.
• Caps: the pages read for this guide do not mention a cap or entry threshold for the CS option; this is not published. The catalog says a CS student whose GPA in option subjects is below 1.9 at the end of the year may be refused permission to continue.
• Size: the admissions site says the first-year class is only about 245 students, with admit rates under 5% in both early and regular rounds.

2. The CS option (2026-27 catalog)

• CS fundamentals: CS 1 (or CS 1X), CS 2, CS 3x, CS 18, CS 4.
• Intermediate CS: CS 21 Decidability and Tractability, CS 24 Introduction to Computing Systems, CS 38 Introduction to Algorithms.
• Project: one of a CS thesis supervised by CS faculty; a CS project of at least two terms and 18 units; or a three-term sequence in Learning & Vision, Networks & Communication, Quantum & Molecular Computing, Robotics, or Programming Languages.
• Advanced CS: 72 further units of advanced CS, including at least one of a set of theory courses.
• Mathematics and more: Ma 2 and Ma 3, plus one of CS 13, Ma/CS 6a or Ma 121a; technical writing and presentation courses; 18 units of scientific core electives; and breadth units in maths, CS and engineering.
• Totals: Institute core units do not count toward option requirements, option courses cannot be taken pass/fail, and 486 units are needed to graduate.
• Double majors and minor: a second option is possible if all CS requirements are met; students in other options can minor in CS.

3. High school preparation

• Academic requirements: 4 years of maths including a year of calculus, 1 year of physics, 1 year of chemistry, 1 year of biology (recommended), 4 years of English, and 2 years of history or social science (3+ recommended).
• International curricula: IB students need Mathematics HL; A-level students need A-level Maths. Students taking only STEM subjects in their final two years (such as A-level students) need two years of English and two of social studies in their first two years.
• If your school does not offer calculus, physics or chemistry: with documentation from you and your counselor, Caltech accepts a 5 on AP Calculus AB/BC, Chemistry or Physics 1/2/C; a 6 or 7 in IB Mathematics HL or Chemistry or Physics SL/HL (taken by the application deadline); or a Schoolhouse.world course challenge. Part of this page still refers to “fall 2026 first-year applicants”, so check whether this is unchanged for 2027.
• Programming: the academic requirements page does not list programming; CS 1 can be placed out of through the summer placement exam.

4. Application plans and deadlines

• Restrictive Early Action (REA): due 1 November 2026, with decisions (admit, defer or deny) in mid-December. It is not binding, and you have until 1 May 2027 to decide. REA applicants may not apply early action or early decision to other US private institutions, with exceptions including institutions outside the US and public universities such as the University of California.
• Regular Decision (RD): due 4 January 2027, with decisions in mid-March.
• Platform: the Common App or QuestBridge; the fee is USD 85, with waivers available.
• Materials: two teacher letters (one from maths, physics, chemistry or biology and one from English, history, government or economics), the school report and mid-year report, and supplemental essays.

5. Standardized testing

• The SAT or ACT is required. For fall 2027, ACT Writing and Science are not required; Caltech does not use the ACT composite and looks at each subscore.
• Banded review: SAT Math or Reading and Writing scores of 780–800 (ACT subscores of 35–36) are shown as Bucket A and 750–770 (ACT 33–34) as Bucket B, with the exact score hidden; below 750 (ACT below 33), the exact score is shown to the committee.
• Score deadlines: by 30 November 2026 for REA and 31 December 2026 for RD, including resubmissions.
• AP and IB: report every AP and IB exam taken, whatever the score; only enrolling students send official results.

6. Students at high schools in China

• International applicants: non-US citizens or permanent residents attending secondary school outside the US. Apart from financial need, the process and review are the same for everyone.
• Transcripts: official transcripts sent directly by your school, showing class titles, grades and predicted grades. If your school does not teach in English, send the original and an English translation; applications with any untranslated part will not be reviewed.
• Gaokao: Caltech does not mention the Gaokao; check with the admissions office.
• English: see section 8. Caltech also recommends an InitialView conversation and writing sample for all international applicants; it is not required.

7. Students at Canadian high schools

• Caltech does not list separate course or grade requirements for Canadian provinces, including BC; prepare against the academic requirements in section 3.
• Students at Canadian high schools without US citizenship or permanent residence apply as international applicants.
• International applicants must apply for aid when they apply for admission or cannot apply later; Caltech says it may make exceptions for citizens of Canada and Mexico.

8. English requirements

• Who must submit: all international applicants, unless English is your native language or the main language of instruction at your secondary school; in the latter case it is strongly recommended. Test before the application deadline.
• Minimum scores: IELTS 7 overall and 7 in each area; TOEFL before 21 January 2026, 100 overall and 25 in each area, from that date 5 overall and 5 in each area; Duolingo 130 overall and 130 in each area.

9. Costs and financial aid

• 2026-27 costs (USD, on campus): tuition 68,574; fees 2,655; housing 12,711; food 9,285; total direct costs 93,225; indirect costs (books, personal expenses and so on) 5,397. New students also pay a one-time USD 600 orientation fee, and Caltech’s student health plan costs USD 5,388 (waivable with comparable coverage). Costs for 2027-28 have not been published.
• Need-aware for international students: Caltech is need-blind for domestic students but need-aware for international students, because international aid funds are limited, so financial need may be a factor in admission. Caltech meets 100% of demonstrated need for admitted students.
• There are no merit scholarships; aid is need-based only.

10. Transfer students

• Who can apply: students who have finished secondary school and earned credit at another college or university. Transfer students enter as second- or third-year students, in fall only.
• Dates: due 1 February 2027, entrance exams due 15 February, decisions in mid-April, reply by 1 June. The same page also says the application and requirements for fall 2027 will be available in late fall and that what is shown is for fall 2026 applicants, so check the dates when they are published.
• Entrance exams: one in mathematics and one in physics, 4 hours each, taken at home under the Honor Code with no calculators, references or aids. Caltech looks for courses such as single- and multivariable calculus, linear algebra, classical mechanics, electromagnetism and statistical physics, and special relativity.
• Letters: two from college professors in maths, science or engineering.
• Credit: faculty review each course after admission and set your class standing; Caltech cannot say in advance whether a course will transfer.
• No aid for international transfer students: plan to pay the full cost.

Checklist

Students at high schools in China:

• Apply through the Common App by 1 November 2026 (REA) or 4 January 2027 (RD); declare CS at the end of the first year
• 4 years of maths including calculus, plus physics and chemistry; IB students need Maths HL, A-level students need A-level Maths
• The SAT or ACT is required (by 30 November for REA, 31 December for RD); report all AP and IB results
• English: IELTS 7 (7 in each area), new TOEFL 5 or Duolingo 130; InitialView recommended
• Apply for aid at the same time as admission if you need it

Students at Canadian high schools (including BC and Vancouver):

• Same deadlines and tests; you apply as an international applicant, and Canadian citizens may have an exception on aid timing

Transfer students:

• Apply by about 1 February and complete the maths and physics exams by 15 February; you enter as a second- or third-year student
• No aid for international transfer students

Sources: California Institute of Technology, Catalog: Computer Science option and minor; Computing + Mathematical Sciences: undergraduate CS; Majors and minors; First year; Academic requirements for first-year applicants; Application requirements; Deadlines; Standardized tests; International applicants; Transfer deadlines; Transfer entrance examinations and preparation; International transfer applicants; Afford; 2026-27 cost of attendance. Information is for fall 2027 entry (costs are 2026-27 figures; option requirements are from the 2026-27 catalog). Check Caltech for the latest details.