BlogAI + Anki
ChatGPT vs Claude vs Gemini for Anki cards: I tested all 3
A short handout and a dense 22-page chapter with 15 diagrams, three runs each, every card graded blind. Here's where each one breaks.
Omar··9 min read
On a short handout, all three chatbots write good cards. On a dense chapter with diagrams, AnkiDecks wins clearly: 99% correct, 1 repeat instead of 7–22, and 109 diagram cards instead of 0. Claude is the best chatbot.
Lots of students make Anki cards with a chatbot now. I wanted to know which one is actually best at it, so I tested them instead of guessing. Twice: once on an easy file, once on a hard one.
The results at a glance
Wrong or made-up cards
Lower is better
- ChatGPT
- Claude
- Gemini
- AnkiDecks
Repeated cards per deck
Lower is better
- ChatGPT
- Claude
- Gemini
- AnkiDecks
Diagram cards
Image occlusion · higher is better
- ChatGPT
- Claude
- Gemini
- AnkiDecks
How I tested it
- Test 1, easy: an 11-page cardiology handout from the NIH’s free training notes. It’s our sample PDF, so you can repeat it.
- Test 2, hard: a 22-page textbook chapter on heart anatomy (about 9,000 words) with 15 labelled diagrams, from OpenStax Anatomy and Physiology, a free textbook.
- The models behind the apps: GPT-5.6 Luna (free ChatGPT’s default since August, reported by GIGAZINE), Claude Sonnet 5.5 and Gemini 3.8 Flash. I ran them through their APIs with the same page text AnkiDecks read. The apps read PDFs themselves, so they can behave a little differently.
- One prompt: the medical prompt from our free prompt page, asking for exactly as many cards as AnkiDecks made from the same file (24, then 276), so every deck is the same size.
- Three runs each, because the same chatbot gives different cards every time.
- Graded blind. Two AI judges (Claude Opus 5.5 and GPT-5.6 Sol) checked cards against the text without knowing which tool wrote them: every card in test 1, a random 80 per deck in test 2. Repeats were counted on every card: two cards with almost the same wording.
Can ChatGPT make Anki cards? Test 1: a short handout
Yes, with one catch. First I typed what most people type: “Make Anki flashcards from this lecture.” All three said yes, and each answered in a different shape.
Below are Anki-ready flashcards in **tab-separated format**. Copy the contents into a `.tsv` or `.txt` file and import into Anki using **Tab** as the field separator. ```tsv What type of organ is the heart? The heart is a four-chambered muscular organ. What is the approximate size and shape of the heart? It is roughly the size and shape of a man's closed fist. Where is most of the heart's mass located relative to the midline? Approximately two-thirds of the heart's mass lies to the left of the midline. What encloses the heart? The heart is enclosed in a pericardial sac. What lines the pericardial sac? The pericardial sac is lined by the parietal layer of a serous membrane. What is the visceral layer of the serous pericardium called? The epicardium. What are the three layers of the heart wall? Epicardium, myocardium, and endocardium. What is the outermost layer of the heart wall? The epicardium. What is the middle layer of the heart wall? The myocardium. What is the innermost layer of the heart wall? The endocardium.
55 cards in a code blockGPT-5.6 Luna
# Anki Flashcards: Structure and Physiology of the Heart **Import:** Save the block below as a `.txt` file and use File → Import. Fields are tab-separated (Front, Back, Tags). If your tabs get converted to spaces when you copy and paste, use a spreadsheet and export as CSV instead. ``` How many chambers does the human heart have, and what is its approximate size? Four chambers; roughly the size of a man's closed fist. cardiology::structure How is the heart's mass positioned relative to the midline? About two-thirds of the mass lies to the left of midline. cardiology::structure What encloses the heart? The pericardial sac, lined with the parietal layer of a serous membrane. cardiology::structure What does the visceral layer of the serous membrane form? The epicardium. cardiology::structure Name the three layers of the heart wall from outer to inner. Epicardium (outer), myocardium (middle), endocardium (inner). cardiology::wall Which heart wall layer is the outer layer? Epicardium. cardiology::wall Which heart wall layer is the middle layer? Myocardium. cardiology::wall Which heart wall layer is the inner layer? Endocardium. cardiology::wall What are the four chambers of the heart? Right atrium, right ventricle, left atrium, left ventricle. cardiology::chambers
44 cards with tags and notesSonnet 5.5
Here is a complete set of Anki flashcards created from the lecture notes. They follow the minimum-information principle (atomic, clear, and unambiguous) to optimize active recall and spaced repetition. --- ### **Deck: Cardiology – Structure and Physiology of the Heart** #### **Card 1: Anatomy & Position** * **Front:** Where is the heart positioned relative to the midline of the thoracic cavity? * **Back:** Approximately **two-thirds** of its mass lies to the **left** of the midline. --- #### **Card 2: Pericardium** * **Front:** What layer of the pericardial sac forms the **epicardium** (outer layer of the heart wall)? * **Back:** The **visceral layer** of the serous membrane. --- #### **Card 3: Heart Wall Layers**
21 cards in markdown: no import3.8 Flash
ChatGPT and Claude gave text you can save as a file for Anki. Gemini gave formatted cards that Anki can’t import, so you’d copy them by hand. Claude also added a fair note that one sentence on page 11 is oddly worded. So the catch: tell the chatbot the exact format. With our prompt, all three answered in Anki-ready lines:
How many chambers does the human heart have?;Four What forms the epicardium?;The visceral layer of the serous membrane What are the three layers of the heart wall?;Epicardium myocardium and endocardium Which chambers receive blood from veins?;The atria Which chambers forcefully pump blood out of the heart?;The ventricles What blood does the right atrium receive?;Deoxygenated blood from systemic veins What blood does the left atrium receive?;Oxygenated blood from pulmonary veins What are valves between atria and ventricles called?;Atrioventricular or cuspid valves
Asked for 24 · got 25GPT-5.6 Luna
Heart wall outer layer?;Epicardium Heart wall middle layer?;Myocardium Heart wall inner layer?;Endocardium What forms the epicardium?;The visceral layer of the serous membrane of the pericardial sac Why are ventricle walls thicker than atrial walls?;More myocardium, reflecting the greater force they must generate What do the atria do?;Thin-walled chambers that receive blood from veins What do the ventricles do?;Thick-walled chambers that forcefully pump blood out of the heart What blood does the right atrium receive?;Deoxygenated blood from systemic veins
Asked for 24 · got 24Sonnet 5.5
Location of the majority of the heart mass;Two-thirds to the left of the midline Serous membrane layer that forms the epicardium;Visceral layer of the serous membrane Three layers of the heart wall from outer to inner;Epicardium, myocardium, and endocardium Cause of variations in thickness among heart chamber walls;Amount of myocardium present Heart chamber that receives deoxygenated blood from systemic veins;Right atrium Heart chamber that receives oxygenated blood from pulmonary veins;Left atrium Class of heart valves located between atria and ventricles;Atrioventricular valves (cuspid valves) Valve located between the right atrium and right ventricle;Tricuspid valve
Asked for 24 · got 243.8 Flash
| Short handout | ChatGPT | Claude | Gemini | AnkiDecks |
|---|---|---|---|---|
| Fully correct | 97% | 99% | 95% | 100% |
| Wrong, or added a fact | 0% | 0% | 4% | 0% |
| Made the 24 cards asked | 0 of 3 runs | 3 of 3 | 3 of 3 | 24 |
| Page on every card | No | No | No | Yes |
Honestly, closer than I expected. On a short, clean handout all three write good cards, and a chatbot is free and done in seconds. The one thing none of them do is tell you where each card came from:
When the ventricles contract, which valves close and why?
Atrioventricular valves close to prevent backflow into the atria.
Which AI is best for a long PDF? Test 2: a dense chapter
Real lectures aren’t 10 clean pages. So I gave them 22 dense textbook pages and asked for 276 cards. This is where they start to slip.
| Dense chapter | ChatGPT | Claude | Gemini | AnkiDecks |
|---|---|---|---|---|
| Fully correct | 95% | 98% | 90% | 99% |
| Wrong | 0.6% | 0% | 3.5% | 0% |
| Added a fact not in the chapter | 0.8% | 0% | 7.3% | 0.6% |
| Repeated cards per deck | 7–16 | 8–14 | 14–22 | 1 |
| Made the 276 cards asked | 2 of 3 runs | 2 of 3 | 1 of 3 | 276 |
| Image occlusion cards | 0 | 0 | 0 | 109 |
| Page on every card | No | No | No | Yes |
- Gemini got worse with length: 3.5% wrong, and 7.3% added things the chapter doesn’t say. Some are true, but on an exam you’re marked on your course, not the internet. It also made 360 and 338 cards when I asked for 276.
- All three repeat themselves: 7 to 22 near-identical cards per deck.
- Claude stayed accurate (98%, nothing made up). It’s the one I’d pick if you use a chatbot.
What the repeats cost you
A repeat looks harmless, but Anki shows it to you again and again. Using the model behind our review calculator, one card costs about 7.5 reviews over a 4-month semester at Anki’s default 90% retention. So per chapter like this:
- ChatGPT and Claude (about 10 repeats): about 75 wasted reviews, roughly 12 minutes.
- Gemini (about 18 repeats): about 135 wasted reviews, roughly 22 minutes.
- AnkiDecks (1 repeat): about 8 reviews, roughly 1 minute.
Multiply that by every lecture in a semester. AnkiDecks writes more cards than it keeps: for this chapter it drafted 374 and threw out 98 before I saw them (43 low-value, 24 weak fill-in-the-blanks, 23 that asked two things at once, 6 repeats, 1 whose quote wasn’t in the chapter and 1 that pointed at “the slide”).
Can ChatGPT make image occlusion cards?
No, not in my test. Anatomy is half diagrams, and in Anki you learn them with image occlusion: boxes hide the labels, and you name what’s under each one. I gave each chatbot four of the chapter’s diagrams and asked for image occlusion cards.
I can make these as **image-occlusion cards with one card per label**. The four diagrams contain approximately **70 occlusions**: 1. **Dual circulation diagram** — 28 labels 2. **Internal structures of the heart** — 25 labels 3. **Chordae tendineae and papillary muscles photograph** — 3 labels 4. **Coronary circulation, anterior and posterior views** — 24 label instances I’ll use the standard format: - **Front:** original diagram with one label and its leader line occluded - **Back:** same diagram with the hidden label revealed - Repeated labels in separate locations will receive separate cards. - The textbook paragraph text will be excluded. The labels covered are: ### 1. Dual circulation
A list of labels · 0 cardsGPT-5.6 Luna
I can't generate image files or an .apkg from here, so I can't build the finished deck. What I can give you is a checked label inventory for each figure (so you don't miss any) and a short workflow for Anki's built-in Image Occlusion (Anki 23.10+). ## Workflow (about 5 minutes per figure) 1. **Crop** each diagram out of its page screenshot, leaving out the caption and body text. 2. In Anki, choose **Add → Note Type: Image Occlusion** and select the cropped image. 3. Use the **rectangle tool** to cover each label's text, not the leader line. The line then still points to the structure you're naming. 4. Select **"Hide All, Guess One"** if you want to learn each label with the others still visible as context. Select **"Hide One, Guess One"** if you want the other labels to stay visible as cues. 5. Put the figure number in **Header** (e.g., "Fig 19.9 – Internal heart, anterior view"). 6. Put "OpenStax A&P 2e, CC BY 4.0" in **Back Extra**. 7. Tag the notes, e.g., `A&P::Heart::Fig19.9`. **Splits:** Figure 19.4 is really two diagrams (heart and whole-body circuit), and Figure 19.15 has two views. Make each one a separate note so the images stay readable. --- ## Figure 19.4 – Dual circulation (page 5)
Steps to do it by hand · 0 cardsSonnet 5.5
Here is a complete checklist of all labels across the four figures, structured so you can crop each diagram and place your image occlusion masks in Anki (using Anki’s built-in **Image Occlusion** tool or the **Image Occlusion Enhanced** add-on). --- ### How to Set This Up in Anki 1. **Crop each diagram** to remove surrounding body text so the image is clean and legible on mobile and desktop. 2. In Anki, click **Add**, select the note type **Image Occlusion**, and paste the cropped image. 3. Draw rectangular masks over each text label line/box. 4. Set mode to **"Hide All, Guess One"** (recommended for anatomical diagrams so surrounding labels don't give away the answer). --- ## 1. Figure 19.4: Dual System of the Human Blood Circulation ### Top Diagram: Blood Flow Schematic Through the Heart #### Left Side (Anatomical Right): * `Superior vena cava`
A checklist + steps · 0 cards3.8 Flash
- ChatGPT listed about 70 labels, then asked me to upload each diagram cropped. (The ChatGPT app can run code, so it might get further there. Through the API it made no cards.)
- Claude said straight away it can’t make image files, and gave a 7-step guide to do it by hand in Anki, “about 5 minutes per figure”.
- Gemini gave a checklist and the same by-hand steps.
At 5 minutes a figure, the chapter’s 12 usable diagrams are an hour of drawing boxes. AnkiDecks found them, boxed 182 labels and made 109 cards from the key ones:

What this means for your files
| Your file | What I’d use |
|---|---|
| A short handout or your own notes (up to ~10 pages) | Claude with our prompt, or AnkiDecks if you want the page on every card. |
| A long PDF or textbook chapter | AnkiDecks. Fewer wrong cards, almost no repeats, and every card checked against its page. |
| Slides or PDFs with labelled diagrams | AnkiDecks. The chatbots made 0 diagram cards; you’d box them by hand. |
| A lecture you’ll be examined on | AnkiDecks. Checking a card takes a glance at its quote, not a search through the slides. |
What each one is best for
- Claude: the best chatbot. Most accurate in both tests and nothing made up. One slip in test 1: a semicolon inside a card, which splits into the wrong fields when you import it. If you like Claude, AnkiDecks works inside Claude too.
- ChatGPT: fine, but doesn’t count. I asked for 24 cards and got 25, 27 and 26. It also dropped commas in lists (“Epicardium myocardium and endocardium”).
- Gemini: good on short texts. On the long chapter it added the most outside facts and made the most repeats.
- AnkiDecks: for lectures you’ll be tested on. Most accurate, 1 repeat, image occlusion from your diagrams, and the line and page on every card. It’s slower (7 minutes for this chapter in my test). The free plan covers 15 pages a file and 20 diagram cards a month; Pro covers 100 pages a file and 300 diagram cards a month, and Max has no monthly limit on diagram cards. See plans.
My pick: a chatbot for a quick handout, AnkiDecks for real lectures. That’s what I do, and it’s why I built it. Want to check my work? Here’s every answer, prompt and grade from both tests (zip).
Try it on your next lecture
Every card with its page, plus diagram cards. 3 free decks a month.
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Questions
- Which AI makes the best Anki cards?
- Of the three chatbots, Claude: 98–99% fully correct in both tests and no made-up facts. On a dense chapter AnkiDecks did better still (99%, 1 repeat instead of 7–22), and it was the only tool that made image occlusion cards from diagrams.
- Can ChatGPT make image occlusion cards for Anki?
- Not in my test. Given four diagrams, ChatGPT, Claude and Gemini all listed the labels and explained how to draw the boxes in Anki yourself, but none made a card you could import. AnkiDecks made 109 from the chapter's 12 usable diagrams.
- Do AI chatbots make up facts on flashcards?
- Rarely on a short text. On the dense chapter, 7.3% of Gemini's graded cards added something that wasn't in the chapter and 3.5% were wrong. ChatGPT was under 1% and Claude 0%. None of them show the page a card came from, so you can't check them quickly.
- Is it OK to use ChatGPT for Anki cards?
- For a short handout or your own notes, yes: ask for one card per line in a fixed format and check every card. For long lectures, watch for repeats and facts from outside your course, and diagrams still have to be boxed by hand.
- Is AnkiDecks just ChatGPT with extra steps?
- No. It checks every card against your file and drops any card whose quote isn't in it, removes repeats, keeps the page and exact line on each card, turns diagrams into image occlusion cards, and downloads a ready Anki deck.