Gin Rummy scoring: knock, gin, undercut

A Gin Rummy hand is decided by one comparison: your deadwood against your opponent’s. This guide uses the 20-point gin and 10-point undercut bonuses. Some sets use 25 for both, and you must pick one system for the whole match.

Counting deadwood

Deadwood is every card not in a meld. Aces count 1, number cards count their face value, and jacks, queens and kings count 10.

Suppose your ten cards are 3♠ 3♥ 3♦, 6♣ 7♣ 8♣, and A♦ 2♠ 2♥ 5♥. The first six cards are melds. The four unmatched cards total 1 + 2 + 2 + 5 = 10, so you may knock.

You may arrange your cards to give the lowest legal total, but one card cannot belong to two melds.

Knocking

You may knock after drawing when your deadwood is 10 or less after your discard. Show your melds and deadwood.

Your opponent then shows their hand and may lay off unmatched cards onto your melds: a fourth card of the same rank onto a set, or an adjacent card of the same suit onto a run. Cards cannot be laid off onto your deadwood, and you never lay off onto your opponent’s melds.

Only after layoffs do both players total their remaining deadwood.

Scoring a knock

Compare deadwood after layoffs.

• Knocker lower: the knocker scores the difference.
• Opponent equal or lower: the opponent has undercut the knocker and scores the difference plus 10.

Example 1. You knock with 6. Your opponent holds 15 but lays off a 7 onto your set, leaving 8. You score 8 − 6 = 2.

Example 2. You knock with 9. Your opponent reduces to 4. They undercut you and score 9 − 4 + 10 = 15.

Example 3. You knock with 7 and your opponent also has 7. Equal deadwood is an undercut: the difference is 0, so they score just the 10 bonus.

Going gin

If all ten cards are melded after your final discard, you have gin. Your opponent may not lay off. You score 20 plus the opponent’s full deadwood.

Example 4. Your opponent is left with 23 deadwood. You score 20 + 23 = 43.

Common scoring mistakes

• Letting the knocker lay off. Only the opponent lays off, and only against a knock.
• Laying off against gin. It is never allowed.
• Forgetting layoffs before counting. They can turn a knock into an undercut.
• Scoring equal deadwood for the knocker. Equal is an undercut.
• Mixing 25-point bonuses into a 20/10 match. Decide before the first deal.
• Scoring a hand cancelled at two stock cards. If only two cards remain in the stock and no one has knocked, the hand is cancelled with no score and the same dealer deals again.

Winning the match

Only the hand winner scores; melds earn nothing by themselves and deadwood does not carry over. The first player to reach 100 after a completed hand wins. Commercial sets also describe game and shutout bonuses, which this ruleset does not include.