if you think it’s too long to read, you can use example parts, they work as some sort of TL;DR.
but if you’re new I recommend reading the whole thing.
Deck Options
I think deck options is the most important thing about anki that everybody should know how to work with and modify.
Here I will explain things about deck options that I wish I had known when I started using anki and that are important for anki users to understand.
it controls anki’s scheduler so if you use inappropriate settings, you might have to review too many cards every day and you might get frustrated with your reviews, or you might not see cards in a deck often enough and you might keep forgetting them.
I personally think how effective anki is for you depends on your deck options settings, and messing with it without knowing what you’re doing might make anki the most useless app for you. but if you use the right settings it most likely will be the best app you can use to memorize almost anything.
In this post I will just explain how everything works and how it affects scheduling, and won’t recommend any settings because I think you should tweak with them and find out for yourself what works best for you.
Opening Deck Options
You can open deck options by:
- Clicking on gear icon in front of your deck name and selecting “Options” from the menu that appears
Or - Clicking on deck name and going to deck overview and pressing “O” on deck overview screen
Here’s how deck options looks like.
Creating Option Groups
If you have multiple decks/subjects you might want to use different settings for each one of them. if you need to use different settings for different decks you’ll have to create option groups.
To create option groups:
- click on “Manage…” button in top right corner of deck options window
- select “Add” from the menu that appears.
- Now type in the name that you want to use for your options group.
congrats 
you just created your options groups.
NOTE: You don’t have to create different option groups for every deck you have. some settings might be effective for more than one deck.
Now that you created your deck options, in “New Cards”, “Reviews”, and “Lapses” I’ll explain what each options does.
New Cards
This tab, as the name suggests, modifies how anki treats new cards.
Steps (in minutes)
This options defines learning steps for new cards.
You’ll pass one learning step on a new/learn card each time you press “Good” on that card.
Say your learning steps are like this -> 10 30 1440
The first one (10) is for the “Again” button. Each time you press again on a new/learn card, it’s interval will be 10 minutes, meaning that anki will show you that card in 10 minutes. (might show you sooner based on “Tools -> Preferences -> Learn ahead limit”)
The second number (30) is the first learning step. when you first see a new card, if you press “Good” on it, it’s interval will be 30 minutes, meaning that anki will show you the card again in 30 minutes.
The third number (1440 = 1 day) is the second learning step. when you have pressed good on a new card, the second time when you see it, if you press “Good” on it, it’s interval will be 1440 minutes (1 day), meaning that anki will show you that card again in 1 day.
now that you have finished learning steps, the cards exits learning phase and it’ll get an ease (Starting ease) and it will be a graduated card.
when you finish learning steps, the cards exits learning and the next interval will be “Graduating interval”
Graduating interval
When you finish learning a card (when you finish learning steps) after you see the card again, it’s interval will be “Graduating interval”.
Say your graduating interval is 3 days and your learning steps are like this -> 10 30 1440
when you see you card after last learning step (after 1 day) if you press “Good” on that card, it’s interval will be 3 days, meaning anki will show you the card again after 3 days.
from there on the interval will be calculated based on your performance and review settings.
Easy interval
it controls easy button interval for cards in learning phase.
If you press “Easy” on a card in any learning step, the card will graduate (it’ll exit the learning phase) it’s interval will be “Easy interval”
Say your Easy interval is 4 days.
if you press easy on a card in learning phase, it’s interval will be 4 days, meaning anki will show you that card again in 4 days
Starting ease
Anki will give each card in review phase a unique ease which controls how often you see a card.
Starting ease is the ease that anki gives cards when they exit learning phase and get graduated.
You’ll see how it affects how often you see a card in “Reviews”
Examples
I know some of you find those explanations confusing
Here’s an example card. feel free to go back and read and compare this part with the previous parts till you fully understand what exactly happens.
Steps (in minutes): 10 30 1440
Graduating interval: 3 days
Easy interval: 4 days
new card -> (Press “Good”) -> show again in 10 minutes
the same card after 10 minutes is passed -> (Press “Good”) -> show again in 30 minutes
the same card after 30 minutes is passed -> (Press “Good”) -> show again in 1 day
the same card after 1 day is passed -> (Press “Good”) -> show again in 3 days
- If you press again in any of those steps, the card will go back to the first learning step
- if you press hard in any of those steps, the card will stay in that step. it’s interval will be Previous interval (sometimes it’s interval is average of good and again intervals)
- if you press Easy in any of those steps, the card will exit learning phase, and it’s interval will be 4 days (Easy interval).
Difference between graduated cards and cards in learning phase
You might be wondering what happens when a card graduates, or what’s the difference between a graduated card and a card in learning phase.
The difference is in the card’s ease. a card in learning phase doesn’t have ease, and no matter how many times you press “Again” on that card, it won’t affect it’s ease. but for the graduated cards, each time you press again anki will decrease that card’s ease by 20% which will affect all future reviews for that card. (Explanation is review settings)
Reviews
This tab controls scheduling for cards in review phase.
Scheduling for review cards is based on previous interval (how long it’s been since you last reviews the card to be exact) and easy bonus, interval modifier, hard interval, card’s ease.
each one of these plays a role based on what button you have pressed.
Example
I think explaining what those options do in form of an example is much easier and less confusing.
Again
if you press Again on a review card, it’s exit review state and will enter re-learning phase and it’s ease will be decrease by 20% (more about re-learning phase in lapses)
Hard
if you press Hard on a review card, it’s previous interval will be multiplied by Hard interval and it’s ease will be decreased by 15% telling anki to show you the card more frequently
Here’s an example card:
Previous interval: 10 days
Hard interval: 120%
review card that you reviewed 10 days ago -> (Press “Hard”) -> show again in 12 days (10 * 1.2) [-15% ease]
same card after 12 days -> (Press “Hard”) -> show again in 14 days (12 * 1.2) [-15% ease]
same card after 14 days -> (Press “Hard”) -> show again in 17 days (14 * 1.2) [-15% ease]
Good
if you press Good on a review card, it’s previous interval will be multiplied by card’s ease
Here’s an example card:
Previous interval: 10 days
Ease: 200%
review card that you reviewed 10 days ago -> (Press “Good”) -> show again in 20 days (10 * 2)
same card after 20 days -> (Press “Good”) -> show again in 40 days (20 * 2)
same card after 40 days -> (Press “Good”) -> show again in 80 days (40 * 2)
Easy
if you press Easy on a review card, it’s previous interval will be multiplied by (Ease * Easy bonus) and it’s ease will be increased by 15%
Here’s an example card:
Previous interval: 10 days
Ease: 200%
Easy bonus: 150%
review card that you reviewed 10 days ago -> (Press “Easy”) -> show again in 30 days (10 * 2 * 1.5) [+15% ease]
same card after 30 days -> (Press “Easy”) -> show again in 97 days (30 * 2.15 * 1.5) [+15% ease]
same card after 97 days -> (Press “Easy”) -> show again in 334 days (97 * 2.3 * 1.5) [+15% ease]
Interval modifier
all intervals for review cards will be multiplied by interval modifier.
There are 2 things that limit how much interval modifier can decrease the interval:
- Hard interval can’t be less than previous interval
- Good interval can’t be less than hard interval
so if a buttons interval is less than previous interval, anki will automatically change it to previous interval
Here are the same examples with an interval modifier of 80%:
Hard
Previous interval: 10 days
Hard interval: 120%
Interval Modifier: 80%
review card that you reviewed 10 days ago -> (Press “Hard”) -> show again in 10 days (10 * 1.2 * 0.8 = 9.6 -> automatically changed to 10) [-15% ease]
same card after 10 days -> (Press “Hard”) -> show again in 10 days (10 * 1.2 * 0.8) [-15% ease]
same card after 10 days -> (Press “Hard”) -> show again in 10 days (10 * 1.2 * 0.8) [-15% ease]
Good
Previous interval: 10 days
Ease: 200%
Interval Modifier: 80%
review card that you reviewed 10 days ago -> (Press “Good”) -> show again in 16 days (10 * 2 * 0.8)
same card after 16 days -> (Press “Good”) -> show again in 26 days (16 * 2 * 0.8)
same card after 26 days -> (Press “Good”) -> show again in 41 days (26 * 2 * 0.8)
Easy
Previous interval: 10 days
Ease: 200%
Easy bonus: 150%
Interval Modifier: 80%
review card that you reviewed 10 days ago -> (Press “Easy”) -> show again in 24 days (10 * 2 * 1.5 * 0.8) [+15% ease]
same card after 24 days -> (Press “Easy”) -> show again in 62 days (24 * 2.15 * 1.5 * 0.8) [+15% ease]
same card after 62 days -> (Press “Easy”) -> show again in 171 days (62 * 2.3 * 1.5 * 0.8) [+15% ease]
Lapses
Controls scheduling for cards in re-learning phase.
Steps (in minutes)
it’s the same thing as learning steps for new card.
when you fail a card (press “Again”) the card enters re-learning phase (same as learning phase) and before it becomes a review card again, you’ll have to pass all re-learning steps or press easy on the card.
New interval
it works as the graduating interval in New cards tab. the difference is that you can set it based on cards previous interval.
Example
Previous Interval: 50 days
Steps (in minutes): 10 30 1440
New interval: 50%
review card that you reviewed 50 days ago -> (Press “Again”) -> show again in 10 minutes
same card after 10 minutes -> (Press “Good”) -> show again in 30 minutes
same card after 30 minutes -> (Press “Good”) -> show again in 1 day
same card after 1 day -> (Press “Good”) -> show again in 25 days (50 * 0.5 | previous interval * new interval)
if you press “Easy” in any of those steps this is what happens:
card -> (Press “Easy”) -> show again in 25 days (50 * 0.5)
Minimum interval
it controls the minimum interval for a lapsed card.
Example
Previous interval: 10 days
steps (in minutes): 10 30 1440
New interval: 20%
Minimum interval: 5 days
review card that you reviewed 10 days ago -> (Press “Again”) -> show again in 10 minutes
same card after 10 minutes -> (Press “Good”) -> show again in 30 minutes
same card after 30 minutes -> (Press “Good”) -> show again in 1 day
same card after 1 day -> (Press “Good”) -> show again in 5 days (10 * 0.2 = 2 which is less than the minimum interval (5 days) so anki automatically changes it to 5 days)
Fuzz Factor
When you press a button that say 30 days, anki might give the card a different interval. it’s due to fuzz factor and doesn’t mean anki’s algorithm is broken or it’s not functioning properly.
anki automatically applies a fuzz factor to all cards so when you introduce some new cards, you won’t have to review all of them in the same day.
The fuzz factor is usually between 15 to 20 percent.
Example
Here’s an example for you to understand fuzz factor better
Interval for card A: 10 days (on any button)
interval for card B: 20 days (on any button)
interval for card C: 30 days (on any button)
interval for card D: 40 days (on any button)
Now here’s the interval that we expect anki to give these cards:
for card A the interval should be something from 8 to 12 days
for card B the interval should be something from 16 to 24 days
for card C the interval should be something from 25 to 35 days
for card D the interval should be something from 34 to 46 days
this was my understanding of deck options and how it works. if you don’t understand some parts of it, feel free to ask questions.
don’t modify the settings unless you know what you’re doing.
you don’t have to change everything you see
)
I was just slightly irritated because I finally stumbled upon the FAQ section with the algorithm… but you’re right, it does not matter for the calculations as such.