Blackjack 21+3 — Payouts, Odds & House Edge

21+3 is the most popular blackjack side bet. It combines your two cards with the dealer's up-card to make a three-card poker hand — and pays if those three cards form a flush, straight, three of a kind or straight flush. It is settled right after the deal, before you play your hand.

Common payouts

The most widespread paytable (6 decks) pays on a type-based scale:

• Flush — 5:1
• Straight — 10:1
• Three of a Kind — 30:1
• Straight Flush — 40:1
• Suited Three of a Kind — 100:1

Some casinos use a flat 9:1 for any qualifying hand instead. Always check the paytable posted at the table — it changes the house edge significantly.

Odds and house edge

On the type-based table above, qualifying hands hit roughly once every 13 hands, and the house edge is about 3.2% with six decks (it drifts up with more decks and down with fewer). The flat 9:1 version is much worse, around 8%. Either way it dwarfs the ~0.5% of the base game played with basic strategy.

It doesn't change how you play

21+3 is resolved before your decisions, so it has zero effect on the correct hit/stand/double/split play — those still come from the EV of each action:

It is a fun, high-variance flutter, not a way to lower the house edge. Compare it with Perfect Pairs and the other side bets, and keep your real money on the base hand.