Vocabulary is the foundation of language learning. To reach fluency, you'll need to learn thousands of words. And one of the most popular tools for doing this is Anki — a spaced repetition system (SRS) that shows you flashcards at increasing intervals, right before you're likely to forget them. Vocabulary Size
Anki is a flashcard app that uses a spaced repetition algorithm. You study cards, tell the app whether you remembered them, and it schedules your next review. Cards you know well get shown less often. Cards you struggle with come up more frequently.
You can think of Anki like an Instant Pot in your kitchen — it's a specific, fairly niche tool that lets you do a lot more than you could without it. But you still need ingredients, a recipe, and your own effort to actually cook something. Just owning an Instant Pot won't make you a chef, and just having Anki won't make you fluent.
Anki is popular specifically because it's just the framework. You fill it with what you want to learn. There are thousands of pre-made decks available, or you can create your own cards from your immersion (which is called sentence mining). Sentence Mining
Anki is great at:
Anki does not:
The key insight is this: Anki creates the initial dictionary entry. Your immersion fills it in. Study primes your brain to notice and learn words; immersion is where the actual acquisition happens. The Pillars of Language Learning
If you're going to study on your phone, set things up on your computer first and then sync to your phone. It's much easier that way. On Android, the app is called AnkiDroid. On iOS, it's called Anki (not AnkiApp — that's a different thing).
New cards per day: Start with 5–10. If you're a total beginner, start with 5–7. If you've studied some of the language before, 10 is fine. This might feel slow at first, but after a couple of weeks, reviews pile up and you'll be glad you kept it manageable.
FSRS: Make sure FSRS is enabled in your deck settings. It's a newer study algorithm that makes your review time shorter and more efficient.
Open a deck, click "Study Now," and look at the card. Try to remember what's on the back. Press the spacebar to flip it. If you got it right, hit "Good." If not, hit "Again."
You can entirely ignore the "Easy" and "Hard" buttons (or remove them with the pass/fail addon). If you were to use them correctly, they can slightly improve your review time, but only if you're consistent about what "Easy" and "Hard" actually mean. It's easier for most people to ignore them.
Don't overthink the buttons. You're just telling Anki what you need to practice more. "Again" isn't failure — it's feedback.
Keep studying until you see the "Congratulations" screen. This means you've finished all your new cards and reviews for the day. This is how you prevent cards from piling up and making Anki miserable.
Make it comfortable. Anki out of the box is pretty ugly. Take some time to make your cards look nice — adjust text size, use colors you like, make sure the audio sounds good. If you're going to use this tool for years, it should be pleasant to use.
Be picky about your cards. If a card is giving you trouble, delete it or suspend it. Words aren't rare Pokémon — you're going to come across them again in your immersion. A bad card isn't your fault; it's the card's fault. Get rid of it and move on.
Don't do too much. More cards per day does not mean better learning. Trying to jam 20–30 new cards per day is like trying to sprint through a marathon. It works for a few days and then you collapse. An average of 5–10 new cards per day, sustained over months, beats any short burst.
Find your time and place. Choose a specific time, device, and location for your daily Anki. Doing it with your morning coffee, or in the 15 minutes before work — whatever works. When 98% of your Anki happens in one place, that last 2% is easy to fill in. It becomes like brushing your teeth.
Focus on hit rate, not streaks. A streak feels great until it breaks, and then it's devastating. Instead, track your "hit rate" — the percentage of days you've done Anki in the last 6 weeks. Missing one day barely affects a 90% hit rate, but it destroys a streak. The habit matters more than the number. Habit Health
Balance study with immersion. Our recommendation is to spend at most 25–30% of your learning time on study (which includes Anki) and the rest on immersion. If you're struggling to remember words in Anki, the answer isn't more Anki — it's more immersion. Seeing words in real context fills in those dictionary entries and makes everything click. The Pillars of Language Learning
There are many free decks on AnkiWeb. Thousands of Anki decks other language learners have made and put out for free. Some are very good (this Japanese deck, for example), but others are pretty bad or entirely broken.
The rating system in AnkiWeb helps to bring the better decks to the top, but it's a very simple system and newer decks appear at the very bottom, even if they're better.
Try searching in AnkiWeb for your target language. Look for the terms "frequency" or "common words" decks, not themed vocabulary lists. Ideally with audio and around 1000 cards.
Refold sells fundamental vocabulary decks for several languages. We decided to make them since we saw several fundamental issues with the decks on AnkiWeb.
Our decks include high-quality audio for the words AND sentences, images, clear definitions, a nice card design... but most importantly, we hand selected the words to ensure you're only learning the most important words.
Many free decks just put the 1000 most common words into a deck and call it done. But we think that spending a bunch of time learning "the" or "his" or even "conversación" (in Spanish) isn't a good use of your time.
There are official Refold decks for:
La mayoría tienen versiones para hispanohablantes también
While we're confident that our decks are the best options, we don't have options for ALL languages! But the Refold community can help you find a deck for your target language.
As a beginner, pre-made frequency decks are ideal. They give you high-quality cards for the most common words. But once you're in the intermediate stages, making your own cards from your immersion (sentence mining) is more effective — the cards are easier to remember because they come from content you actually engaged with, and they're more relevant to what you're currently learning. Sentence Mining
Spaced repetition as a learning technique is well-supported by memory research. Nakata (2015) studied its effects on second language vocabulary specifically and found significant benefits from spaced review compared to massed practice. Serfaty (2023) further explored how much relearning is necessary to retain vocabulary long-term.
The claim that vocabulary is the strongest predictor of reading comprehension comes from Nation (2001, 2006) and Stæhr (2008). Nation's work established the widely-cited coverage figures: the most common 1,000 words cover roughly 70% of text, and 2,000 words cover about 80%. These figures vary by language and corpus, but the pattern holds cross-linguistically. Vocabulary Size
The distinction between memorizing a word and acquiring it — the idea that Anki creates a dictionary entry but immersion fills it in — reflects the difference between deliberate and incidental vocabulary learning. Webb (2020) and others have shown that incidental acquisition through reading and listening is a major source of vocabulary growth, while deliberate study (like flashcards) is most effective as a way to prime the learner for that incidental acquisition. Nation (2001) argues that both deliberate and incidental learning have important roles, which is exactly the balance we recommend.