How many flashcards a day? What the spacing research fixes, and what it leaves to you

Last updated: October 2026 · By Thomas Lovas Lokoy, founder & builder of BrainLoop. AI-assisted draft, checked against the sources at the end. Where I give a number of cards, it is my recommendation, not a study result; I say so each time.

"How many flashcards should I do a day?" is one of the most searched flashcard questions, and the straight answer is that no study I could find hands you a number. What the research does settle is how the cards should be scheduled and what you should do with each one. Get those two things right and the daily count becomes a question of how much time you have, which is a question you can answer yourself.

What the research does not tell you

Memory researchers mostly do not study "cards per day". They study two things that matter far more: whether you retrieve the answer or just reread it, and how far apart your sessions are. A deck of twenty cards drilled once and forgotten is worse than ten cards you revisit three times across a fortnight. So any blog that gives you "exactly 30 cards a day" is making it up, including, if I did it without a flag, this one.

What it does tell you: test, don't reread

In a 2006 study by Roediger and Karpicke, students learned prose passages either by restudying them or by taking memory tests on them. On an immediate test, restudying looked better. On tests two days and a week later, the students who had been tested remembered substantially more, even though restudying had made the other group more confident.¹ Two lessons sit in that result. First, the benefit of testing shows up with delay, which is exactly when an exam or a conversation happens. Second, rereading inflates confidence without inflating memory, which is why it feels so productive.

A flashcard is only a test if you commit to an answer before you flip it. The BrainLoop Flashcards app is built so you cannot skip that step: the card shows the question, you decide, you click to reveal, and you have to press Got It! or Didn't Know before the next card appears. The honest grade is the retrieval practice. Reveal-and-nod is rereading with extra steps.

What it does tell you: the gap should be long, and it should grow

The largest study on spacing I know of is Cepeda and colleagues' 2008 work in Psychological Science. More than 1,350 people learned a set of facts, came back for a review session after a gap of up to three and a half months, and were tested up to a year later. Longer gaps first improved retention and then slowly reduced it, and the sweet spot moved: "The optimal gap increased as test delay increased."² As a share of the time until the final test, the best gap shrank from roughly 20–40 per cent when the test was a week away to 5–10 per cent when it was a year away.

Translate that into cards. If you need the material in a week, a review gap of a day or two is in the right zone. If you need it for a year, reviews a few weeks apart are closer to the mark than daily cramming. Either way, the lesson is not "more cards today", it is "the same cards again later, after a gap that feels slightly too long".

John Dunlosky's summary of the study-strategy literature for American Educator reaches the same conclusion from the other side: of the techniques his team reviewed, practice testing and distributed practice were rated the most effective, rereading had "inconsistent effects", and highlighting "failed to help students of all sorts". His practical advice is modest and achievable: set aside blocks of time through the week, and "two short study blocks per week may be enough to begin studying new material".³

So how many cards? My recommendation, flagged as such

Nothing below is from a study. It is how I use the research in practice.

Size the sitting by time, not by cards. Ten to fifteen focused minutes is a sitting. In the BrainLoop app the built-in decks are five cards and a generated deck is six, which makes one to three decks a comfortable sitting of roughly five to eighteen cards. If you can do one more deck honestly, do it; if you are nodding through reveals, stop.

Let yesterday's cards come first. Before you open anything new, run a deck you already graded yesterday. The ones you marked Didn't Know are where the memory is still forming; the ones you nailed can wait longer, which is the spacing effect doing its job for free.

Keep new cards small. Six new cards a day for a week is forty-two cards that you have retrieved several times each. Forty new cards on Sunday is forty cards you have seen once.

Widen the gap as the score rises. A deck you score 5/5 on two days running does not need tomorrow. Give it three or four days, then a week. If the score drops, the gap was too long; shorten it and carry on. That is the whole algorithm, run by hand.

A week that follows the evidence

• Day 1: one built-in deck, two honest passes (5 cards).
• Day 2: the same deck once, then one generated deck on your own topic (11 cards).
• Day 3: both decks once (11 cards).
• Day 4: only the cards you got wrong on day 3, plus one new deck (roughly 8–10 cards).
• Day 5: rest from new material; run the oldest deck once (5 cards).
• Day 6: the two newest decks (12 cards).
• Day 7: every deck once, grade honestly, and note which ones can now wait a week.

That is somewhere between fifty and sixty retrievals in a week, each spaced, with no sitting over fifteen minutes. The count was never the point; the gaps and the honest grading were.

Two practical notes about the app

Generated decks in BrainLoop are not saved between visits, so write down the topic you typed if a deck is worth repeating, and expect the regenerated cards to differ slightly. Each generation uses one of your daily AI allowance (five a day signed out, ten on the free plan). Grading cards never costs anything, which is convenient, because grading is the part that does the work.

The one-line answer

As many cards as you can retrieve honestly in ten to fifteen minutes, repeated after a gap that grows as your score does. The studies fix the method; the number is yours.

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Sources

Footnotes

1. Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: taking memory tests improves long-term retention. Psychological Science. Abstract via Europe PMC: https://europepmc.org/article/MED/16507066 ↩

2. Cepeda, N. J., Vul, E., Rohrer, D., Wixted, J. T., & Pashler, H. (2008). Spacing effects in learning: a temporal ridgeline of optimal retention. Psychological Science. Abstract via Europe PMC: https://europepmc.org/article/MED/19076480 ↩

3. Dunlosky, J. (2013). Strengthening the Student Toolbox: Study Strategies to Boost Learning. American Educator, Fall 2013. https://www.aft.org/ae/fall2013/dunlosky ↩