What is a leech in Anki? What “card was a leech” means and what to do

A leech is a card you keep forgetting. Anki counts a lapse every time you press Again on a card that has already graduated to review. When a card reaches 8 lapses, Anki tags its note "leech". If the Leech action is set to Suspend Card, it also suspends the card so it stops coming up.

So when Anki pops up “Card was a leech.”, the card has just reached the leech threshold: with the default settings, that was its 8th lapse, the 8th time you pressed Again on it as a review card. Its note now carries the leech tag.

Leeches matter because they cost far more time than normal cards. Each lapse sends the card back to short relearning steps, resets its interval and lowers its ease by 20 points, so a single leech can take dozens of reviews a year while a healthy card takes a handful.

What counts as a lapse

• Again on a review card counts. That's the only thing that does.
• Again on a new or learning card doesn't count. The card hasn't graduated yet.
• Hard doesn't count. Hard is a pass, even though it lowers ease. More on that in Hard vs Again.

The default settings

These are in Deck Options, under Lapses:

After the first warning, Anki warns again every half threshold. With the default of 8, that's at 12, 16, 20 lapses and so on.

How to find your leeches

In the Browse window, search for tag:leech to see every leech note, or is:suspended to see every suspended card. To bring a card back, select it and use Toggle Suspend. Bury vs suspend explains how suspending differs from burying. Removing the leech tag is optional; the lapse count stays on the card either way.

What to do with a leech

Unsuspending it without changing anything usually means it fails again. These work better:

1. Rewrite the card. Most leeches have too much on them, or ask something vague. Split one card into two, or make the question narrower. See how to write good flashcards.
2. Add context. A word on its own is easy to confuse; a short example sentence often fixes it, and so does turning the card into a cloze card. See sentence cards vs word cards, or beginner Spanish sentences for examples.
3. Separate look-alikes. If you keep mixing up two cards, suspend one until the other is solid, then bring it back. Kana are a classic case: シ and ツ, ソ and ン in the katakana chart.
4. Delete it. If the card isn't worth the time, delete it. Not every word in a deck needs learning now.

Leeches and ease hell

Each lapse takes 20 points off ease, and ease never goes below 130%. A leech is usually stuck at that floor, so even after you fix it, its intervals grow slowly until you rate it Easy a few times. What is ease hell explains how that happens and ease factor explained has the numbers.

Common questions

What is the leech threshold in Anki?

It's the number of lapses that marks a card as a leech: 8 by default. Change it in Deck Options, under Lapses. A lower number flags trouble cards sooner; a higher one gives them more chances first.

Does Anki suspend leeches automatically?

Only if you tell it to. The default Leech action, Tag Only, tags the note and shows the pop-up but keeps the card in your reviews. Switch the Leech action to Suspend Card to have leeches taken out until you fix them.

Why do I keep getting the leech pop-up for the same card?

After the first warning, Anki warns again every half threshold: with the default of 8, at 12, 16, 20 lapses and so on. The pop-up keeps coming until the card stops lapsing, so rewriting it is the real fix.

In Decks

Decks uses SM-2 with the same lapse rules as Anki: Again on a review card sends it back to a 10-minute relearning step, resets its interval to 1 day and lowers its ease by 20 points. Decks doesn't tag or suspend leeches; cards you keep failing stay in your reviews. If a card has become easy after you've fixed it, rating it Easy is how its ease recovers.