We Analyzed 18,000 Flashcard Reviews: What Actually Helps You Learn

By<br>Charlie Groves<br>Published 28 July 2026

We Analyzed 18,000 Flashcard Reviews: What Actually Helps You Learn

Most study advice is a rehash of the same 140-year-old lab experiment. We had something different sitting in our own database: 18,217 real flashcard review events from 667 students studying everything from anatomy to the bar exam. So instead of citing Ebbinghaus again, we ran the numbers ourselves.

The dataset covers every graded flashcard review logged on StudyCards AI between September 21, 2025 and July 28, 2026, aggregated and stripped of anything user-identifiable before analysis. Here is what the data actually shows.

Key Takeaways

Accuracy on the same card jumps from 69.0% on the first attempt to 97.7% by the fourth repeat (n=15,104 down to n=215).

Study sessions on decks of 50+ cards are completed only 7.8% of the time, versus 25.0% for decks of 10 cards or fewer.

Students' own "easy / medium / hard" ratings track real performance almost exactly: 95.1% vs. 72.3% vs. 47.4% correct.

Cards rated "hard" take almost twice as long to answer as cards rated "easy" (8.9 seconds vs. 5.7 seconds, median).

Where this data comes from

StudyCards AI lets students upload a PDF (lecture slides, a textbook chapter, a study guide) and turns it into a deck of flashcards. Every time someone answers a card during a study session, we log whether they got it right, how long they took, and how they rated the card's difficulty afterward. That log is the same data that powers spaced repetition scheduling, and over ten months we collected enough data to make some interesting discoveries.

Before running any of the numbers below, we checked for the two things that ruin this kind of analysis: bots and outliers. No single account accounted for more than about 5% of all reviews, and we excluded one internal test account. We also excluded any reviews where the user took more than 10 minutes to answer a card as it's likely they just left the tab open.

Methodology note: this is usage data from one flashcard app rather than a controlled experiment. We can show what correlates with what, but we can't prove causation the way a lab study could.

Repetition works, and the jump is bigger than you'd think

Students get a flashcard right 69.0% of the time on their first attempt (n=15,104). By the second time they see that same card, accuracy climbs to 80.5% (n=2,228). By the third attempt it's 89.7% (n=505), and by the fourth, 97.7% (n=215). Sample size drops off fast after that, so we're not going to pretend the curve keeps climbing forever, but the first four attempts show a clean, consistent trend.

This isn't a new discovery. "The testing effect", the idea that practice improves recall, is well established in cognitive science. What's notable is seeing it this cleanly in real app usage rather than a lab setting with volunteers who know they're being studied. Real students, using a real app, on their own schedule, still show the same trend.

Accuracy climbs with repeat attempts<br>First attempt: 69.0% correct, n=15,104. Second attempt: 80.5% correct, n=2,228. Third attempt: 89.7% correct, n=505. Fourth attempt: 97.7% correct, n=215. Data: StudyCards AI internal usage, 2025-2026.

0%<br>25%<br>50%<br>75%<br>100%

69.0%<br>Attempt 1<br>n=15,104

80.5%<br>Attempt 2<br>n=2,228

89.7%<br>Attempt 3<br>n=505

97.7%<br>Attempt 4<br>n=215

Source: StudyCards AI internal usage data (2025-2026), 15,104 flashcards

Accuracy on the same flashcard climbs from 69% on the first attempt to 97.7% by the fourth repeat review.

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Caveat: we did not find a clean relationship between the length of the gap between reviews and how well people remembered the card. The spacing effect idea that longer, well-timed gaps between reviews boost retention more than short ones, is a much harder thing to isolate from real-world usage data, where people review cards whenever they happen to open the app rather than on a controlled schedule. We looked for it and the signal was too noisy to publish with confidence, so we're not claiming it here. As we collect more data, we'll revisit this.

Bigger decks get abandoned

Across 1,593 study sessions, completion rate falls steadily as deck size grows. Sessions on decks of 10 cards or fewer are completed 25.0% of the time. That drops to 23.1% for 11-20 card decks, 16.8% for 21-30, 13.9% for 31-50, and just 7.8% for decks of 50 or more cards.

Bigger decks get abandoned more often<br>Completion rate by deck size: 1-10 cards 25.0% (n=12), 11-20 cards 23.1% (n=52), 21-30 cards 16.8% (n=113), 31-50 cards...