You Knock to declare to your opponent you are ending the round. You can only knock if the total deadwood points left in your hand, after the final discard, is 10 points or less.
You reveal your meld's and indicate how many deadwood points you have. You then calculate your deadwood points and compare your hand's score to your opponent's.
You must pick up a card from the draw pile or discard pile before knocking (even if you do not need it).
There are three results when a player knocks: Gin Hand, Knock Hand or an Undercut.
If you knock with zero deadwood points remaining you have a Gin Hand. You get a 25 point bonus plus the amount of deadwood in your opponent's hand and the round is over.
Knock Hand or Undercut
When you've knocked with between 1 and 10 deadwood points, your opponent is allowed to play any un-melded cards they have with your melds. Those are called "Layoffs". For example, if you have the 3-4-5 of clubs your opponent could add the 6 of clubs from their deadwood to the end of your run to improve their hand.
Take the difference between your deadwood and your opponent's. If you have less deadwood points after layoffs, that is a Knock Hand and you score, if it's equal to or more it is an Undercut and your opponent scores.
For a knock hand you add the difference to your total score.
For an Undercut your opponent gets the difference in deadwood plus a 25 point bonus!
Example Knock Hand
There are 11 cards in the example below, it's your turn and you want to knock. We must make one discard.
- We have a 3-4-5 of Spade run.
- We have a group of three 9's
- We have a group of three Jacks
- We have a 7 of Clubs and an Ace of Spades remaining as deadwood. These are the only cards not part of a meld.
Let's discard the 7 of clubs for our example. This will leave us only with the single Ace. The Ace is not used in a meld and counts as 1 deadwood point. If your opponent has 2 or more deadwood points you score! Otherwise it would result in an undercut and your opponent would score.
Note: If you had discarded the Ace of Spades you would be left with 7 deadwood points (from the 7 of Clubs).
Knocking on Yimmaw
Playing on Yimmaw.com, you are shown the "knock fist" icon when you are allowed to end the round. You choose the card you want to discard with. The game will prevent you from knocking with a card that will put your deadwood over 10 points. However, it will not stop you from discarding a card that will leave you with a larger amount of deadwood.
Layoffs are automatically applied. This keeps the games quick.
Some variations of Gin Rummy have a Big Gin bonus. If you can use all 11 cards in your hand and you do not need a discard you get a slightly larger bonus than a regular gin. This is usually 30 points.