A good default is to review 1, 3, 7, 14 and 30 days after you first learn something, then every few months. The ideal gap depends on how long you need to remember: in a study of 1,354 learners (Cepeda et al., 2008), the best gap was about 3 days for a test a week away and about 27 days for a test a year away. Apps like Anki go further and set each card's interval from your own answers.
| When you need to remember it | Suggested reviews after first learning |
|---|---|
| In 1 week | Day 1, day 3 |
| In 1 month | Day 1, day 3, day 7, day 14 |
| In 1 year or longer | Day 1, 3, 7, 14, 30, then every 2 to 3 months |
The spacing research behind this, including Cepeda et al. (2008), is summarised in our spaced repetition statistics.
Why does Anki show you a card after 1 day, then a few days, then weeks? Here's the science behind the 1-3-7-14-30 spaced repetition schedule and how to tell if your intervals are working.
Memory decays along a forgetting curve. The optimal time to review is just before you forget - not too early (wasting a review), not too late (after forgetting). Spaced repetition intervals are calculated to hit that precise moment, and they grow longer each time you successfully recall.
Each time you successfully recall a memory, you don't just remember it - you strengthen it. The memory becomes more stable. A more stable memory decays more slowly. This is why the intervals grow exponentially:
| Review # | Typical interval | What happened |
|---|---|---|
| Learning (1st) | 10 minutes | New card, very fragile memory |
| Graduating | 1 day | Card leaves learning queue |
| Review 1 | 3 to 4 days | First long-term review |
| Review 2 | 8 to 12 days | Stability increasing |
| Review 3 | 20 to 35 days | Memory becoming robust |
| Review 4 | 2 to 4 months | Long-term memory |
| Review 5+ | 6 months to 2 years | Near-permanent memory |
These are approximate. Your actual intervals depend on which buttons you press and the algorithm used (SM-2 vs FSRS). FSRS produces more accurate intervals by modelling each card individually through AI-powered spaced repetition and optimization.
When you press Again (forgot the card), two things happen:
This is why good card design matters so much. A card that you consistently fail because it's ambiguous or tests two things at once will never have a long interval - it'll perpetually reset, wasting review time. See how to create Anki cards for how to fix this.
In Anki's old SM-2 algorithm, every Again press reduces the card's "ease factor" by 20 percentage points (for example from 250% to 230%). Ease factor determines how fast intervals grow. After several Again presses, a card might have an ease factor of 130% - meaning it barely grows at all, and you'll be seeing it every few days forever.
This is called "ease hell." Cards stuck in ease hell consume a disproportionate amount of your daily reviews. The fix is either:
FSRS replaces the ease factor with a stability variable. Stability measures how long it will take for your recall probability to drop to your target retention (e.g., 90%). The next interval is simply calculated as the time until you're expected to drop below 90% recall.
This means:
The most common mistake is obsessing over whether your intervals "look right." If you're using FSRS with a 90% retention target, your intervals are already optimized for your personal review history. Trust the algorithm.
What actually matters: reviewing every day (consistency beats optimization), having well-designed atomic cards, and not pressing Easy to inflate intervals artificially. See the Anki settings guide and FSRS algorithm explanation for the full setup.
The "Desired Retention" setting is one of the most misunderstood parts of spaced repetition. Many users aim for 95% or 99% retention, thinking the more they remember, the better. But retention and workload don't rise together in a straight line. The Anki manual notes that above 90% the workload increases very quickly, and above 97% it can be overwhelming.
As you push for near-perfect recall, the algorithm has to cut the intervals a lot to close that last 5% gap. For most learners, 85% to 90% is the "sweet spot." Intervals grow much faster, there's less burnout, and you still remember most of it. When choosing your target, consider these factors:
A common frustration is the "leech" card, a card that you consistently fail regardless of the algorithm. The problem is usually encoding, not the spaced repetition interval. Spaced repetition is a tool for retention, not acquisition. If you try to memorize a fact you don't understand, you are relying on rote memory, which is far more fragile and fades much faster than understanding.
To fix this, "pre-process" the information before it goes into your SRS. Break complex ideas into atomic pieces and make sure you can explain the concept in your own words first. Tools like StudyCards AI can help. They turn dense material into atomic cards that follow the Minimum Information Principle, which are much easier for the brain to hold on to.
Proper intervals only matter if your cards are well-designed. StudyCards AI creates atomic, context-rich flashcards from your notes - structured to work perfectly with Anki's spaced repetition system.
Start Free - Build Your Optimized Deck →A simple, widely used schedule is to review 1, 3, 7, 14 and 30 days after first learning something, then every few months. Research shows the best gap depends on how long you need to remember: in Cepeda et al. (2008), it was about 3 days for a test one week away and about 27 days for a test a year away.
It is a fixed review plan: review new material 1 day, 3 days, 7 days, 14 days and 30 days after you first learn it. Each gap is roughly double the last, which matches how memories become more stable with each successful review.
With the older SM-2 scheduler, each Good answer multiplies the interval by the card's ease, which starts at 250%. Again lowers ease by 20 percentage points and Hard by 15. With FSRS, Anki instead predicts when your recall will drop to your target retention and schedules the review then.
An algorithm such as FSRS adapts each card's interval to how well you actually know it, so it usually beats a fixed schedule. Fixed intervals like 1-3-7-14-30 are fine for paper flashcards or notes where no app is tracking your answers.
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