Filtered Decks & Cramming

When you study a regular deck in Anki, only a limited number of cards are shown: the cards Anki thinks you are about to forget, and a daily limit of new cards. This is generally useful, as it ensures you don't spend more time studying than necessary. But sometimes it can be useful to step outside of these normal limits, such as when you need to review for a test, focus on particular material, and so on. To make this possible, Anki provides a different type of deck called a 'filtered deck'.

Filtered decks offer a lot of possibilities. They can be used for previewing cards, cramming cards before a test, studying particular tags, catching up on a backlog with a particular sort order, reviewing ahead of schedule, going over the day's failed cards, and more.

Custom Study

The easiest way to create a filtered deck is with the Custom Study button, which appears at the bottom of the screen when you click on a deck. It offers some convenient preset filters for common tasks like reviewing the cards that you have failed that day. It will create a filtered deck called "Custom Study Session" and automatically open it for you.

If an existing "Custom Study Session" deck exists, it will be emptied before a new one is created. If you wish to keep a custom study deck, you can rename it from the deck list.

Here is a summary of each of the options:

Increase today's new card limit
Add more new cards to the deck you are currently studying. Note that unlike other options, this does 'not' create a new filtered deck, it modifies the existing deck.

Increase today's review card limit
If not all reviews due today were shown because of the daily review limit, this option allows you to show more of them. As with the new cards option, this modifies the existing deck.

Review forgotten cards
Show all the cards, for which you've answered Again (1) within the number of days you specify.

Review ahead
Show cards that will be due in the near future (the number of days you specify). This is useful for working through some of your older cards before a vacation, but it will not help with cards you have learnt recently. Please see the reviewing ahead section below for more info.

Preview new cards
Show cards that you have recently added, without converting them to review cards as they are answered.

Study by card state or tag
Select a certain number of cards from the current deck to study. You can choose to select new cards only, due cards only, or all cards; after you click "Choose Tags", you can also limit the selected cards by tags. If you wish to see all the cards in the deck (for instance, to study before a big test), you can set the number of cards to more than the number of cards in the deck.

Home Decks

When a card is moved to a filtered deck, it retains a link to the deck, from which it came. That previous deck is said to be the card's 'home deck'.

Cards automatically return to their home deck after they are studied in the filtered deck. This can be after a single review, or after multiple reviews, depending on your settings.

It is also possible to move all cards back to their home decks at once:

  • The "Empty" button in the study overview moves all cards in the filtered deck back to their home deck, but does not delete the empty filtered deck. This can be useful if you want to fill it again later (using the Rebuild button).

  • Deleting a filtered deck does the same thing as "Empty" does, but also removes the emptied deck from the deck list. No cards are deleted when you delete a filtered deck.

Creating Manually

Advanced users can create filtered decks with arbitrary search strings (or 'filters'), instead of relying on the preset filters. To create a filtered deck manually, choose Create Filtered Deck from the Tools menu.

When you click the Build button, Anki finds cards that match the settings you specified, and temporarily moves them from their existing decks into your new filtered deck for study.

If you wish to fetch cards again using the same filter options (for instance, if you want to study all cards with a particular tag every day), you can use the Rebuild button at the bottom of the deck's overview screen.

The search area controls what cards Anki will gather. All of the searches possible in the browser are also possible for filtered decks, such as limiting to tags, finding cards forgotten a certain number of times, and so on. Please see the searching section of the manual for more information on the different possibilities.

Filtered decks cannot pull in cards that are suspended, buried, or already in a different filtered deck. For this reason, a search in the browser may reveal cards that do not end up in the filtered deck.

The limit option controls how many cards will be gathered into the deck. The order you select controls both the order cards are gathered in, and the order they will be reviewed in. If you select "most lapses" and a limit of 20 for example, then Anki will show you only the 20 most lapsed cards.

The enable second filter option allows you to create a filtered deck comprised of two different searches, so that you can, for example, include due cards with one order, and a smaller amount of new cards with a different order.

Order

The "cards selected by" option controls the order that cards will appear in. If the maximum number of cards you select is lower than the number of cards that match the filter criteria, Anki will exclude the cards at the end of this sorted list first.

Oldest seen first
Display those cards first, that you haven't seen in reviews for the longest time.

Random
Randomize the order of all cards that match the filter criteria (use no set order).

Increasing intervals
Display cards that have the smallest interval first.

Decreasing intervals
Display cards that have the largest interval first.

Most lapses
Display those cards first, that you have failed the most times.

Order added
Display cards that you added first (i.e. those cards that have the earliest creation date).

Order due
Display cards with the earliest due date first.

Latest added first
Display cards that you have most recently added to the deck first. (This is the opposite of 'Order added'.)

Relative overdueness
Display cards that you're most likely to have forgotten first. This is useful if you have a large backlog that may take some time to get through, and you want to reduce the chances of forgetting more cards.

When using the SM-2 algorithm, overduessness is determined by comparing how overdue cards are, and how long their interval is. For example, a card with a current interval of 5 days that is overdue by 2 days, will display before a card with a current interval of 10 days that is overdue by 3 days.

When using FSRS, overdueness is calculated based on on each card's retrievability, and the desired retention in the deck preset.

Steps & Returning

By default, Anki will use the steps of a card’s home deck. If a new card would normally be reviewed twice when being learnt, the same thing will happen when you study it in a filtered deck. To learn about how (re)learning steps work, see Deck Options section.

Cards return to their home deck when (re)learning is complete. Thus if you have 3 learning steps, a new card will return to its home deck upon three presses of "Good" or a single press of "Easy".

Filtered decks with rescheduling disabled show 4 buttons. The Again, Hard, and Good buttons have configurable delays. The Easy button removes cards from the filtered deck.

Due Reviews

If the filtered deck includes cards that were due for review, they will be shown like they would have been in their original deck: they appear in the review card count at the bottom of the screen, and there are four choices for how well you remembered. Upon a correct answer, the card will be moved back to its home deck, and its next delay adjusted using the home deck's settings. If you forget the card, it will be shown according to the relearning steps defined in the home deck.

Reviewing Ahead

If your search included cards that are not due, Anki will show the reviews ahead of time.

Anki uses a special algorithm for these reviews that takes into account how early you are reviewing. If the cards were almost due to be shown, they will be given a new delay similar to what they would have received if you had reviewed them on time. If the cards are reviewed soon after they were scheduled however, their new delay will be similar to their previous delay. This calculation works on a sliding scale.

Because reviewing a card shortly after it is scheduled has little impact on scheduling (e.g. a card due tomorrow with a one day interval will remain due tomorrow if reviewed early), the "review ahead" custom study setting is not appropriate for repeated use. If used to go through a week's worth of cards before a trip, the mature cards will be rescheduled into the future and the new cards will remain at small intervals, because you don't know them well enough for them to be rescheduled further. If you review ahead again the next day, all you'll end up doing is going through those same new cards again, to little benefit.

Rescheduling

By default, Anki will return cards to their home decks with altered scheduling, based on your performance in the filtered deck.

To change this behaviour, turn off Reschedule cards based on my answers. When this is turned off, cards are shown in a simple "preview mode", and when they are returned to their original deck, they are returned exactly as they started.

Catching Up

Filtered decks can be useful for catching up when you've fallen behind in your reviews. One Anki user describes the way they use the filtered decks to catch up as follows:

I did this for a backlog of 800 cards with filtered subdecks. Worked
very well for me.

Just Due filter with: "is:due prop:due>-7"

Over Due filter with: "is:due prop:due<=-7"

The Just Due deck will then contain cards that became due in the past
week. That's the deck you should study every day as it gets the cards
that become due regularly. With this you can study as if there weren't
any backlog.

The Over Due deck will contain your backlog — cards which you didn't
study in time. You can study them the same way you would study new
cards. They go back into the regular cards, so the number of overdue
will never grow as long as you keep your Just Due deck in check.

How long it takes depends on how many overdue cards you study each day
in addition to the ones that become due regularly. You can still motor
through them when you feel like it - or you can do a specific number per
day like you would for new cards. Up to you.