Why Your Anki Collection Needs Sub Decks
You’ve been using Anki to study for months, diligently adding cards for biology, Spanish vocabulary, and programming concepts. But now, your main “Biology” deck has over 2000 cards, and finding the specific section on cellular respiration feels like searching for a needle in a haystack. You know there must be a better way to organize this mountain of information.
This is the exact moment when sub decks become your secret weapon. A sub deck is a child deck that lives inside a parent deck, creating a hierarchical folder-like structure. It doesn’t just tidy up your deck list; it fundamentally changes how you interact with your study material, allowing for targeted reviews and clearer mental models of complex subjects.
Many users stick to flat, single-level decks because the process of creating a sub deck isn’t immediately obvious in Anki’s interface. Unlike creating a regular deck, which has a prominent button, sub deck creation requires a specific sequence of clicks and drags. Let’s fix that.
Understanding the Anki Deck Hierarchy
Before you start creating, it’s crucial to grasp how Anki structures your knowledge. Think of your collection as a file system. The top level contains main folders, like “Languages” or “Medicine.” These are your parent decks. Inside “Languages,” you might have folders for “Spanish,” “French,” and “German.” These would be sub decks.
Anki uses a specific naming convention to show this relationship. A sub deck’s name includes the full path of its parent, separated by two colons. For example, if you create a sub deck named “Vocabulary” under a parent deck named “Spanish,” the sub deck will appear in your list as “Spanish::Vocabulary”. This visual cue is how you know the hierarchy is in place.
This structure is more than cosmetic. When you study a parent deck, Anki automatically includes all cards from its sub decks in the review session. This is perfect for doing a broad review of an entire subject. Conversely, you can study just the “Spanish::Vocabulary” sub deck if you want to focus your efforts, leaving grammar cards for another time.
The Core Method: Creating Your First Sub Deck
The most straightforward way to create a sub deck is through the deck overview screen. Open Anki and ensure you are on the main screen where all your decks are listed. This is your starting point.
First, you need the parent deck to exist. If you don’t have one yet, click the “Create Deck” button at the bottom of the window. Name it something broad, like “Neuroscience.” Press OK. Now, “Neuroscience” appears in your deck list.
Next, click “Create Deck” again. This time, in the dialog box, you must type the full hierarchical name. To make a sub deck for “Neuroanatomy,” you would type exactly: Neuroscience::Neuroanatomy. Those two colons are the critical syntax that tells Anki this new deck belongs under “Neuroscience.” Click OK.
Immediately, you’ll see the change. In your deck list, “Neuroanatomy” will now be indented underneath “Neuroscience.” The parent deck will also show a small arrow you can click to collapse or expand the view, hiding or showing its sub decks. You’ve successfully built your first piece of study infrastructure.
Organizing Existing Decks into a Hierarchy
What if you already have a bunch of standalone decks that should be related? You don’t need to delete and recreate them. Anki lets you reorganize by simply renaming.
Right-click on the deck you want to turn into a sub deck. Select “Rename” from the context menu. In the renaming box, you will see the deck’s current name, for example, “Cardiac Physiology.” To make it a sub deck of a parent deck called “Medicine,” you prefix the name with the parent and two colons. Change the name to Medicine::Cardiac Physiology.
When you press OK, the deck will instantly move. It will disappear from its old spot in the flat list and reappear indented under the “Medicine” deck. If the “Medicine” deck didn’t exist before, Anki will automatically create it as a parent. This renaming trick is the fastest way to impose order on a chaotic collection.
You can also use drag-and-drop in the desktop application. Click and hold a deck, then drag it directly on top of another deck. When you release it, the dragged deck will become a sub deck of the one you dropped it onto. The interface will update to show the new hierarchical relationship.
Strategic Uses for Sub Decks in Your Study Flow
Creating the structure is only half the battle. Using it effectively is what boosts your retention. One powerful strategy is to use sub decks for prerequisite knowledge. Your main “Calculus” deck could have sub decks for “Algebra Review,” “Limits,” and “Derivatives.” You can mandate studying the “Algebra Review” sub deck before unlocking the others, building a strong foundation.
Another common use is separating card types. Within a “Japanese” parent deck, you might have sub decks for “Kanji,” “Vocabulary,” and “Grammar Sentences.” This allows you to adjust study settings per card type. Maybe you want Kanji cards to have more learning steps, while Grammar cards use a shorter interval modifier. Sub decks give you that granular control.
For large projects like medical board exams, break down the material by system. A “Pathology” parent deck can have sub decks for “Cardiovascular,” “Pulmonary,” “Renal,” and so on. This mirrors textbook chapters and helps compartmentalize your reviews, preventing cognitive overload.
Managing Reviews Across Parent and Sub Decks
A key point of confusion is how reviews work in a hierarchy. When you click to study a parent deck, Anki gathers all due cards from that parent deck and all its sub decks, mixing them together into one session. This is the default and often desired behavior for integrated review.
If you only want to study a specific sub deck, simply click on the sub deck’s name itself in the list. Anki will then only show cards from that sub deck, ignoring its siblings and parent. This is ideal for last-minute cramming on a specific topic before a test.
You can also set different options groups for each sub deck. Right-click a sub deck, choose “Options,” and you can link it to a unique set of settings for steps, intervals, and daily limits. This means your “Spanish::Irregular Verbs” sub deck can be set to “hardcore” mode with 10-minute learning steps, while your “Spanish::Culture” sub deck uses a more relaxed “vacation” preset.
Troubleshooting Common Sub Deck Issues
Sometimes, the hierarchy doesn’t behave as expected. The most frequent issue is a sub deck not appearing under its parent. This is almost always a typo in the deck name. Check that you used two colons (::) and not one, and ensure the parent deck’s name is spelled exactly right, including capitalization and spaces.
Another problem is wanting to “un-nest” a sub deck—to make it a top-level deck again. The solution is the reverse of the renaming method. Right-click the sub deck, select “Rename,” and delete the parent deck name and the two colons from the beginning of its name. For example, change Medicine::Cardiac Physiology back to just Cardiac Physiology. It will immediately return to the main list.
Be cautious with deleting decks. If you delete a parent deck, Anki will ask if you also want to delete all cards in its sub decks. This is a permanent action. If you only want to remove the parent container but keep the cards, you should first move or rename the sub decks to be independent, as described above, before deleting the now-empty parent.
Syncing Sub Decks with AnkiWeb and Mobile Apps
Your beautifully organized hierarchy on your desktop will sync perfectly to AnkiWeb and the official mobile apps. The structure is part of your collection data. After creating or reorganizing sub decks on your computer, simply press the sync button (the two curved arrows in the top right).
On the Anki mobile app, the hierarchy is displayed with indentation, and you can tap the arrow next to a parent deck to collapse or expand it. The study functionality works identically. This seamless sync ensures your organizational system is always with you, whether you’re reviewing on a phone during your commute or on a laptop at your desk.
Taking Your Anki Organization to the Next Level
Once you’re comfortable with basic sub decks, you can explore nested sub decks—decks within decks within decks. The naming convention extends logically. You could have Science::Biology::Cell Biology::Mitochondria. This allows for extremely deep organization, though it’s best used sparingly to avoid over-complication.
For power users, add-ons like “Hierarchical Tags” or “Deck Stats” can provide even more control and insight into your hierarchical structure. These are community-developed tools that integrate with the sub deck system, offering features like visual statistics per sub deck branch or the ability to study cards based on tags across multiple sub decks.
The ultimate goal is to make your deck structure an intuitive map of the knowledge you’re building. A well-organized collection reduces friction, allowing you to spend less time managing cards and more time actually learning. Start by picking one sprawling deck today, break it into two or three logical sub decks, and experience the immediate clarity it brings to your study sessions.
Your next step is open. Look at your deck list and identify one parent deck waiting to be born. It could be “Certification Exam,” “New Language,” or “Personal Development.” Create it, then begin sorting your existing material into its new, logical home. The few minutes you invest in this setup will pay dividends in focused, efficient learning for months to come.
