Definition
Doubling down doubles your wager. You receive exactly one more card and your turn ends — no further hits allowed.
When to double down (S17, DAS)
Hard hands:
Soft hands:
Why doubling matters
Double-down hands are the most profitable in basic strategy. Hard 11 vs dealer 6, doubled, has an expected value of about +0.668 per dollar wagered — meaning you net roughly 67 cents profit per $1 of original bet, on average. Just hitting hard 11 has a lower EV.
Casual players often skip doubles because doubling "feels risky" — you're putting more money at stake. The math says it's the opposite. Skipping doubles is one of the most expensive habits in blackjack.
DAS — Double After Split
Some tables let you double down after splitting a pair (DAS). For example, you split 8-8, draw a 3 to make 11, and then can double on the 11. DAS is more player-friendly — it lowers the house edge by ~0.13%. Always look for "DAS allowed" on the table placard.
How to double at a real table
Place a second bet equal to your original next to (not on top of) the first bet. Hold up one finger to signal "double." Some casinos restrict doubles to less than the original bet (called "double for less") — rare and unfavorable to the player. Always double the full amount when allowed.
Practice in BJNP
Blackjack Navigator Pro's coaching system shows the correct double decision under your active rule preset. The Practice mode includes a "Doubles" drill theme that focuses specifically on the spots where casual players slip.
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