What does "always increasing next review interval" mean?

In Review setting, what does “always increasing next review interval” actually mean?


By how much is the interval actually increased?

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There was a long discussion a couple of years ago when this was introduced, that led to the current three choices available.

For the “always increasing next review interval” option, I understand that it uses a SM2 algorithm with an easiness factor of 2.5.

There. That should have cleared that up then :joy:

I’m not familiar with the algorithm, so the easiest thing might be to read the old thread starting at @mike’s comment here -


I found this explanation on github:

SM-2 is a simple spaced repetition algorithm. It calculates the number of days to wait before reviewing a piece of information based on how easily the information was remembered today.


Many thanks for the link, @zzcguns.

I can see the debate, but what were the final decisions, @mike?

By how much do the intervals “always increase”?

You can see the results of the final decisions from the interface under “Review Settings”:

However, this doesn’t answer your question about the amount by which the intervals “always increase”. Hopefully @mike can address that.

I think I read somewhere that the interval always doubles, but I don’t remember where and I’m not so sure now. Anyway, I’m counting on that, because I’m using that option right now lol.

The SM2 algorithm comes from the app SuperMemo, a pioneer in flashcard apps.

In school, you maybe used paper flashcards with the Leitner system. Nowadays, apps like Anki made this process digital and far more effective. And before there was Anki, there was the app SuperMemo (from the late 1980s), which did a lot of the foundational work, including figuring out the algorithm when a card should be shown again (the review interval). That algorithm is called SM, or SM2, named after the app SuperMemo.