Duolingo English Test vs Preply 1-on-1 Tutoring
Same Bayesian formula, same rubric — so the difference in scores reflects the difference in the courses, not the difference in how we evaluated them.
Duolingo · Languages
Duolingo English Test
Preply · Languages
Preply 1-on-1 Tutoring
Per-criterion
Adaptive difficulty and integrated skill design are genuine strengths. Weakened by the absence of a formal essay (only a 5-minute writing sample), opinion-based speaking prompts, and a perceived lack of academic rigour versus IELTS and TOEFL among experienced practitioners.
No published answer keys, rubrics, or section-level guidance — the weakest methodology dimension. Some test-takers receive a score range spanning three CEFR levels rather than a single number, making preparation harder than for IELTS or TOEFL.
$65 per attempt with unlimited free score sends versus $220-plus for IELTS. 48-hour results and no test-centre booking add further convenience. The primary reason test-takers choose the DET over alternatives.
At-home, on-demand testing removes scheduling friction and supports repeated attempts. Three-tier human review provides oversight. Weakened by documented AI false-flag incidents and a 72-hour appeal window that can frustrate test-takers.
6,000-plus programs in 110-plus countries accept it, including 98 of the US News Top 100 universities and all Ivy League schools. IELTS is accepted by 12,500-plus organisations — more than double. UK/Australian visa routes and professional bodies don't yet accept at-home tests.
No curriculum — content is whatever the tutor brings. Preply's package model nudges teachers toward longer engagements and marginally more structured plans than italki's pay-per-lesson default, but variance is still large and the platform does not vet pedagogy.
Broad global tutor pool, strong supply in English-as-a-second-language and major European languages. Reviewers find tutors for less-common languages like Khmer at $10-15/hour. Vetting remains the student's job — most learners trial 2-4 tutors before settling.
Per-hour rates ($10-30) overlap with italki, but subscription-style packages and aggressive cancellation friction pull effective value down. Reviewers describe pricing that "always comes up higher, never lower" and packages that can expire on tutor reschedules.
The subscription mechanic is the biggest contrast with italki — pre-paid weekly packages create real commitment that helps learners who would otherwise drift. The same mechanic frustrates anyone who changes tutors or pauses; works for steady users, against churning ones.
Same speaking-and-correction engine as italki and the same outcomes — multiple Hacker News commenters credit weekly Preply tutors with breaking them out of Duolingo plateaus into actual conversation. The product is the tutor, and the tutor works.
Scoring methodology applies identically to every course on the site — see the formula.