When to Double Down in Blackjack
Double hard 11 vs everything, 10 vs 2–9, 9 vs 3–6 — and don't skip the soft doubles: A-2 to A-7 against the dealer's weak cards. Doubling is the only move in blackjack where the casino lets you raise your bet after seeing you're a favorite. Take it.
Hitting, standing, and splitting are about losing less. Doubling is where you actually make money at blackjack — every double on the chart marks a spot where you are statistically the favorite, and the correct response to being the favorite is betting more.
What is doubling down, and when can you do it?
To double down is to double your original bet in exchange for taking exactly one more card — then your turn ends automatically. Win the hand and you win double; lose and you lose double. It's a pure offensive move: you only do it when that one extra card is likely to build a winning hand.
When can you double down? The eligibility rules:
- Only on your first two cards. Once you've hit and taken a third card, doubling is no longer allowed.
- Most casinos let you double on any two cards ("double on anything"). Some stricter or European games limit it to hard totals of 9, 10, or 11 — check the table rules.
- After a split, it depends on the house. "Double after split" (DAS) is allowed at most US tables and slightly helps the player; a few tables don't allow it.
- You normally must double for your full original bet, not less.
So there are really two questions: when you're allowed to double (above) and when you should (the rest of this page). Here's every double that actually makes you money.
The hard doubles
| Your total | Double against | Why |
|---|---|---|
| 11 | Everything (2–A)* | Any ten makes 21; you're the favorite vs every up-card |
| 10 | 2–9 | Same logic — but vs 10/A the dealer's start is too strong |
| 9 | 3–6 | Only into the dealer's bust cards |
*11 vs ace is a double when the dealer hits soft 17 (the common US rule); in S17 games, just hit it. The chart toggles both.
The flagship example, with exact numbers from our engine: 11 vs 6. Hitting earns +33.2¢ per $1. Doubling earns +66.5¢ — precisely twice as much, because you win the same percentage of hands with twice the money out. Even the "weak" double of 11 vs 10 (+18.0¢ doubled vs +11.9¢ hit) is real profit you leave behind by playing timid.
The soft doubles — where most money is left on the table
Players skip these constantly because "I have a 17, why would I double?" The point isn't your current total — it's that with an ace you cannot bust on one card, and the dealer's 4, 5, or 6 busts over 40% of the time (see the odds). Pressure with zero bust risk:
| Your hand | Double against |
|---|---|
| A,2 and A,3 (soft 13–14) | 5, 6 |
| A,4 and A,5 (soft 15–16) | 4, 5, 6 |
| A,6 (soft 17) | 3, 4, 5, 6 |
| A,7 (soft 18) | 2–6 (H17) · 3–6 (S17), else stand vs 7/8 |
| A,8 (soft 19) | 6 only, in H17 games |
Concrete: A-6 vs 6 — hitting earns +12.5¢, standing is a losing −0.6¢, but doubling earns +24.9¢ per $1. That's free money the table is offering anyone who knows the soft section of the chart.
Three doubling rules to remember
- 5,5 is a 10, not a pair. Double it vs 2–9 (+57¢ vs 6). Splitting fives is lighting money on fire (+16¢).
- Never double into a made hand. No doubling 8 or less, and no hard doubles vs 10/A except 11 (H17). The favorite-math has to actually be there.
- If you can't double, the fallback differs. "D" cells fall back to hit; "Ds" cells (soft 18–19 doubles) fall back to stand. The chart legend marks both.
Frequently asked questions
Why only one card when I double?
That's the trade: the casino lets you double your bet mid-hand, but you give up the right to keep hitting. The chart's doubles are exactly the hands where one card is all you wanted anyway.
Can I double for less than my original bet?
Usually yes — and you usually shouldn't. If the spot is worth doubling, it's worth the full double; betting less just shrinks a profitable wager. The only exception is bankroll constraints.
Should I double 11 against a dealer ace?
In H17 games (dealer hits soft 17): yes — it's a 21.5¢-per-$1 edge played as a double. In S17 games: just hit. This is one of only three cells that differ between the two charts — see the soft 17 guide.