How do I use FSRS for exam?

I have a big exam in 69 days, but I don’t know what number to put in the desired hold that would be appropriate for that period of time . When I put that period in “Compute minimum recommended retention” it gives me 0.75

Should I put the “Compute minimum recommended retention” number instead of desired retention?

Do I have to change the desired retention number every day according to the Compute minimum recommended retention?
Or if I don’t change it every day, how many day times should I change it?

Should I reschedule all cards all the time when changing desired retention ?

Do I need a filtered Deck or custom study (to review all cards) 2-3 days before exam time if I use FSRS ?

See this:

It tells you the minimum desired retention you can use. For an exam, you will likely want a higher retention than the minimum.

You have to calculate it only once. However, if you reoptimize the FSRS parameters later, you may want to calculate the minimum retention again.

  1. Choose a high-but-not-crazy-high value of desired retention
  2. Set max. interval in a way that ensures that you will see each card at least once before the exam. For example, if exam is in 90 days, set max. interval to 45 days.
  3. (optional) use the Advance feature of the Helper add-on to study cards ahead of time. It’s basically the opposite of postponing

Do I need a filtered Deck or custom study (to review all cards) 2-3 days before exam time if I use FSRS ?

I studied this deck about 270 days , but when i put 270 days in “Compute minimum recommended retention” he always 0.75 give me

AFAIK they are basically the same thing.

That has happened to me (for a deck I am studying since 2023)

By the way, any specific reason you put the same number as 270 in there? I think you may have misunderstood how this works. You can put a higher number and you’ll basically get a similar figure (± a few percentages).

For 2 unfortunately this can only work with newly reviewed cards. The intervals you already have can not be updated.

Assuming that the algorithm works accurately for you and you rate the cards correctly, you don’t need to use filtered decks before the exam. However, if you don’t want to take any risk, you may want to use filtered decks before the exam.

No problem. It just means that the algorithm has determined that 0.75 is the retention at which you acquire the most knowledge per hour spent reviewing.

However, for exams, you likely want a higher retention. Say, 0.90


when i change the desired retention to 0.90 , should i optimize parameters and reschedule all cards ?

You don’t need optimization. Rescheduling cards is fine.

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You should optimize the parameters at least once. However, they don’t depend on the desired retention. So, you don’t need to re-optimize them after changing the desired retention.

Usually, I don’t recommend rescheduling all cards because it can cause a backlog. However, because you have an exam soon, it would be best to reschedule all cards so that you can reap the benefits of FSRS as quickly as possible.


The following FSRS tutorial should answer most of your queries:


I have never tried reschedule though I would like too (for my super old cards). I just don’t know whether it shows us “how much backlog” will we create. Do you know whether something like that is shown (maybe with a popup)? If not I think it would be a good feature to add.

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You can reschedule all cards using the FSRS Helper add-on. It has an advantage that you don’t need to change the parameters or desired retention to reschedule. If the backlog is too high, you can simply press Ctrl + Z.


I changed the desired retention to 0.90 and I optimized parameters because i wasn’t optimized parameters for 25 days and i Rescheduled all cards . now I have 112 cards for Review(duo) but it’s good some card interval is after exam ?

Well, in spaced repetition, intervals grow continuously (unless you fail the card). So, it should not be a surprise that some cards would be due after the exam.

If you have rated the cards correctly in the past and you trust the algorithm, then don’t worry. If you have any doubt, you can do custom study close to the exam.


As Expertium suggested you should’ve used Maximum Interval to limit intervals if you wanted that.

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Certainly , thanks you

thank you very much