Double Up Blackjack is a casino table game: regular blackjack with one extra option. You play against the dealer only, not against the other players.
Double Up (DU) means looking at your first two cards, doubling your bet and standing. Use it only with a strong hand (mostly 19 or more) against a weak dealer upcard.
The names are close, but it is not the same as Double. Double means doubling your bet and taking one card. Double Up means doubling and taking no card.
How it differs from regular blackjack
- After seeing your first two cards, add a bet equal to your bet and stand. You cannot draw afterwards
- Also allowed on hands after a split and after splitting aces (default)
- Not allowed on a blackjack
- In exchange the dealer also stops on 16. This applies to hands that did not Double Up too
Settlement (default):
- Dealer stops on 16: you win with 21; anything else is a push
- Same total (19 against 19, for example): your original bet comes back, but the Double Up chips lose
- Dealer blackjack: your original bet and the Double Up chips lose. Chips added by doubling or splitting come back
Example. You bet 10 and hold 20 against a 5. You Double Up, so 20 is bet in total.
| Dealer result | Win or loss |
|---|---|
| 17 to 19, or bust | +20 (both bets win) |
| Stops on 16 | 0 (you don’t have 21, so it’s a push) |
| 20 | −10 (your original bet comes back; only the Double Up chips lose) |
| 21 | −20 |
The Double Up chips lose on a tie and on a dealer blackjack. That’s why you can’t casually double against strong cards (10, A).
The full rules are in the rules guide, “Blackjack (Double Up)”.
Which hands to Double Up
In the chart for the default rules (this app’s calculation), you mostly Double Up with 19 or more (A-8 or more).
| Your hand | Double Up against |
|---|---|
| 21 | Every upcard |
| 20 | Anything but an ace |
| 19 | 2 to 8 |
| Hard 18 | 5 and 7 |
| A,7 | 7 |
The chart is this app’s calculation; no chart is published for the default rules.
Example. You have 20 against a 5. Count the original bet as 1.
- Stand: EV about +0.55
- Double Up: 2 is at risk in total. If the dealer ends on 17 to 19 or busts: +2. Stops on 16: 0. On 20: −1. On 21: −2. On average, EV about +1.01
A 5 busts often, and 21, the only total that beats your 20, is rare. Double Up has the higher EV, so this cell is Double Up.
Because the dealer stops on 16, some Stand, Hit, Double and Split decisions differ from regular blackjack too.
The rules change the house edge
| Rules | House edge |
|---|---|
| Default (6 decks, H17, double on any two cards, a dealer blackjack takes the Double Up chips) | 0.764% |
| Default, but the dealer stands on soft 17 (S17) | 0.385% |
| Default, but doubling only on hard 9 to 11 | 0.794% |
| A dealer blackjack returns the Double Up chips (the published rules) | 0.325% (published: 0.32%) |
All are this app’s calculations. For tables that return the Double Up chips on a dealer blackjack, a published chart and a 0.32% house edge exist, and this app’s calculation matches.
The default table and the table that returns the Double Up chips differ only in what happens to those chips on a dealer blackjack. That alone moves the house edge by 0.44 points.
Counting and insurance
- Insurance pays only at a true count (TC) of +3 or more. It depends only on the share of tens among the unseen cards, so it is the same at a Double Up table
- There is no published source for Double Up indexes (the counts at which a decision changes). The app’s values are its own calculation
What to check before you sit down
- Does the dealer stop on 16?
- Which hands can Double Up (after a split, after splitting aces)?
- What happens to the Double Up chips on a tie?
- What happens to the Double Up chips on a dealer blackjack?
- Does the dealer hit soft 17 (H17) or stand (S17)?
- Which hands can double (any two cards, or 9 to 11 only)?
- How many decks?
Practice in the app
In Casino Edge’s blackjack, set the table rules to Double Up to practice with that chart and drill. In the chart, U means Double Up, and cells that differ from regular blackjack carry a dot at the top right. Tap a cell to see the EV of each action.