What is SRS (spaced repetition) and why does it work for learning Chinese?

You're learning Chinese and the characters you knew perfectly well last week have vanished from your memory? Totally normal — and it's exactly the problem that spaced repetition (SRS, for Spaced Repetition System) is designed to solve. It's the method that makes it realistic to memorize thousands of hanzi without burning out.

The forgetting curve, in one sentence

Back in the 1880s, German psychologist Hermann Ebbinghaus showed that memory decays quickly: about 40% of a new piece of information is forgotten within 24 hours if it isn't reviewed. But each review "refreshes" the memory trace and extends how long you can recall it.

SRS uses this property: instead of reviewing everything every day (tiring and inefficient), it shows you each card right before you would forget it. The result: fewer reviews overall, but far better timed.

How it works in practice

After each card you rate how it felt ("easy", "good", "hard", "again"). The algorithm uses your answer to compute the next time this card will appear:

• A card you fail → back in 10 minutes
• A "hard" card → back tomorrow
• A "good" card → back in 3 days
• An "easy" card → back in 7 days, then 15, 30, 60…

The more you succeed on a card, the longer the interval grows. A well-mastered card might only reappear once every 6 months — just often enough that you never lose it.

Why it fits Chinese so well

Chinese is the perfect playground for SRS, for three reasons:

1. The volume is huge: around 5,500 words to reach HSK 6, plus characters, tones and measure words. Without planning, it's unmanageable.
2. Characters look alike: 未 / 末, 己 / 已 / 巳, 请 / 情 / 清… Confusions are constant, and SRS priorities the ones you actually mix up.
3. Tones fade fast: māma, máma, mǎma, màma — without regular review you will confuse them. SRS forces you to hear and re-see each tone at the right time.

SM-2, FSRS, Anki, HanziMemo: what's the difference?

Historically every SRS app ran on SM-2, an algorithm designed by Piotr Woźniak in 1987. It works, but it's rigid: intervals come out of a fixed formula that ignores each card's intrinsic difficulty.

Since 2022, FSRS (Free Spaced Repetition Scheduler) has become the natural successor. It's built on a statistical model of memory ("Difficulty–Stability–Retrievability") trained on millions of real reviews. Concretely, FSRS schedules smarter, which translates into 15–30% fewer reviews for the same retention.

HanziMemo runs on FSRS by default, with a Chinese-specific twist: cards missed on the tone are not weighted the same as cards missed on the meaning. You end up spending more time on what's really blocking you.

The 3 classic beginner traps

1. Too many new cards per day

Adding 100 words on a rainy Sunday feels exciting — until Wednesday, when you have 400 reviews backlogged. The golden rule: 10 to 20 new cards per day, no more. Over a year that's already 4,000 to 7,000 words.

2. Rating "easy" when it wasn't

Your brain loves the illusion of competence. If you hesitated for 3 seconds, it wasn't easy — hit Good or Hard. Otherwise the card disappears too long and you'll fail it next time.

3. Skipping a day and "catching up"

A 60-minute session to compensate for 3 missed days breaks the recall curve. Better to do a short daily session even on busy days.

Can't you learn Chinese without SRS?

Of course you can — people have for centuries. But SRS is, for memorization, what a connected treadmill is for running: it doesn't replace motivation, it makes it far more efficient. For an equal amount of study time, an SRS learner retains significantly more than one re-reading random lists.

The best time to start? Today. Even 10 minutes a day is enough to kick off a streak that can bring you to HSK 3 in under a year. See also our article " How long does it really take to pass HSK 1, 2, 3…?" to set your goals.