International students applying to U.S. boarding schools typically need to demonstrate English proficiency through a standardized test. The two most commonly accepted options are the TOEFL iBT (Test of English as a Foreign Language) and the Duolingo English Test (DET).
Knowing which one to take — and understanding their key differences — can meaningfully affect both your preparation timeline and your results.
Acceptance: check first
Before comparing the tests themselves, verify which your target schools accept. Most boarding schools now accept both, but some still require the TOEFL specifically. Check each school’s admissions page carefully. If even one of your target schools does not accept the DET, the TOEFL is your answer.
Score requirements at a glance
| School tier | TOEFL iBT minimum | Duolingo minimum |
|---|---|---|
| Most selective schools | 90–100 | 110–120 |
| Highly selective | 80–90 | 100–110 |
| Selective | 75–85 | 90–105 |
These are approximate ranges. Always confirm the specific requirement with each school.
Format comparison
TOEFL iBT
- Duration: Approximately 2 hours
- Sections: Reading, Listening, Speaking, Writing
- Delivered: At a certified test centre (in-person)
- Score scale: 0–120 (four sections, each 0–30)
- Results: 4–8 days
- Cost: Approximately $185–$245 (varies by country)
- Retakes: Can retake every 3 days, up to 5 times per year
Duolingo English Test
- Duration: Approximately 1 hour
- Sections: Adaptive literacy section + video interview + writing sample
- Delivered: At home, via webcam
- Score scale: 10–160
- Results: Within 2 days
- Cost: $65 per attempt
- Retakes: Can retake every 30 days, up to 3 times per year
Key differences to know
1. Test centre vs. at home
The TOEFL requires travel to an official test centre. In many countries this is straightforward; in others it involves significant travel time or limited availability. The DET can be taken from home on any computer with a webcam — a major practical advantage for students in regions with few test centres.
2. Adaptive format (DET)
The Duolingo English Test adapts to the student’s responses in real time, making it shorter than the TOEFL but harder to “pace” in the traditional sense. It tests a broader range of skills in a less structured format, which some students find more natural and others find unsettling.
3. Cost
The DET at $65 is significantly cheaper than the TOEFL. For students who may need to retake, the cost difference becomes meaningful — three TOEFL attempts cost over $600 in most markets, versus $195 for three DET attempts.
4. Credibility and familiarity
The TOEFL has been the standard for decades. Some admissions officers have deep familiarity with what a given score means in context. The DET is newer and more variable in how it is perceived. This gap is narrowing, but families applying to schools where they want every possible advantage may prefer the more established test.
5. Preparation resources
TOEFL has a much larger ecosystem of prep materials — official practice tests, prep books, tutors, and online courses. DET preparation resources are growing but remain thinner. If your student benefits from structured preparation, TOEFL may be the easier test to prepare for effectively.
Which should your student take?
Take the TOEFL if:
- One or more target schools require it
- Your student performs better in structured, predictable test formats
- Access to a test centre is not an obstacle
- You want a test result with broad credibility
Take the Duolingo English Test if:
- All target schools accept it
- Test centre access is difficult or expensive
- Your student is comfortable with adaptive, conversational formats
- You need a quick turnaround on results (e.g. applying late in the cycle)
- Cost is a significant factor
Consider taking both if:
- Your list includes schools with different requirements
- Your student is a strong English speaker and the additional cost is manageable
- You want to maximise flexibility in how you present scores
When to test
International students should plan to take their English proficiency test at least 3–4 months before application deadlines — ideally earlier. This allows time for at least one retake if scores fall below target. Since most boarding school applications are due in January, that means sitting the test by October at the latest, and September if possible.
Do not attempt to prepare for both SSAT/ISEE and English proficiency tests simultaneously without a structured plan. The cognitive and time demands are significant.
Navigating the international student application process is more complex than it appears. If your family is applying from outside the U.S., book a free consultation — we work with international families regularly and know the specific challenges involved.