Every deck carries three settings: Review Mode, Retention, and two daily limits. They're first set in the Create new deck form, and apply to every card in the deck. This article covers what each one actually does.
Review Mode
Review Mode controls which side of a card is shown as the front and which as the back during review, and whether that follows your native language or your target language rather than however you originally typed the card.
Four modes are available:
Normal: Shows cards as you created them. The side you typed first stays the front.
Reversed: Shows cards in the opposite direction. Front and back are swapped.
Native on front: Your native language always shows as the front card, your target language as the back card.
Native on back: Your target language always shows as the front card, your native language as the back card.
Normal is free. Reversed, Native on front, and Native on back all require flangu Pro.
Warning
Review Mode is set when you create the deck and cannot be changed afterward. If you open an existing deck's settings, the field is shown locked, with the note: "Review mode cannot be changed as it would disrupt the FSRS algorithm." If you need a different mode, create a new deck with that mode selected.
Retention
Retention is the target probability, at any given review, that you'll still remember the card. It's the number FSRS uses to decide how long to wait before showing a card again.
A lower retention target means fewer reviews: FSRS waits longer between reviews and accepts a higher chance you'll forget in between. A higher retention target means more reviews: FSRS schedules cards sooner to keep your recall probability high.
Retention is set on a slider from 70% to 99%, in steps of 1%. The default is 90%, marked with a "Default" badge whenever the value hasn't been changed.
Unlike Review Mode, retention can be adjusted at any time, not just at creation.
Daily limits
Two settings cap how many cards from the deck can come up in a single day:
| Setting | Default | Controls |
|---|---|---|
| Max new cards/day | 20 | How many cards you haven't studied yet can enter your review queue per day. |
| Max reviews/day | 200 | How many cards from your review cycle, plus any new cards introduced that day, can come up per day. |
New cards draw from both limits at once: introducing one counts against Max new cards/day and against Max reviews/day. Cards already in your review cycle only count against Max reviews/day.
Learning and Relearning cards are never capped by either setting. A card mid-step always comes back when its timer runs out, even on a deck that has otherwise hit its limit for the day. See The review session for how a session actually applies this.
Both settings accept any value from 0 to 9999. Setting Max new cards/day to 0 pauses new cards for that deck for the day. Setting Max reviews/day to 0 pauses both review cards and new cards for that deck for the day, since new cards draw from it too.
Each field shows a "Default" badge in its row whenever it's left at 20 or 200. Like retention, both limits can be changed at any time, not just at creation.