Quanta Study editorial team · 7 October 2026
What is the measured difference between FSRS and SM-2?
The open srs-benchmark reports a log-loss of 0.3460 ± 0.0042 for FSRS-6 on 349,923,850 reviews from 9,999 collections. Lower log-loss means lower prediction error. The published table has no SM-2 row, so it does not provide a numerical FSRS-versus-SM-2 result. The benchmark was retrieved on 5 September 2026.
How the scheduling models differ
| Criterion | FSRS | SM-2 |
|---|---|---|
| Published | 2022 research paper | 1987 |
| Memory state | Difficulty, stability and retrievability | Ease factor and interval |
| Open benchmark value | Log-loss 0.3460 ± 0.0042 | No row in the cited table |
| Current Anki support | Supported | Legacy scheduler available |
| Quanta review flow | FSRS-6 | Not used |
Difficulty
How hard this flashcard is for the learner.
Stability
How long the memory is expected to remain retrievable.
Retrievability
The estimated chance of recalling it now.
What the research does and does not establish
Ye et al. report 220 million behaviour logs and a 12.6% improvement over the state of the art in that study. This is a result from its dataset and evaluation, not a promise that a learner will remember 12.6% more. The later open benchmark reports the FSRS-6 value above on its own dataset. It does not publish the SM-2 comparison number needed for a percentage claim.
Cepeda et al. support the broader spacing effect across many conditions. Their review does not compare today’s FSRS and SM-2 implementations and does not measure Quanta.
How Quanta uses FSRS-6
Quanta uses FSRS-6 in its review flow without a separate scheduler setup. Individual intervals begin to adapt after the first rating. Free forever: 1 topic, no more than 20 flashcards in total, and FSRS. Once over the account lifetime, in the guided entry: 10 AI flashcards and a multiple-choice test with 5 questions, plus 1 summary of a document. Each month 1 AI explanation, 10 dictation minutes and 60 voice formula inputs. Essential adds exam simulation and calendar import.
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