Guides
These guides cover the same decisions TwentyOne trains: basic strategy, table-rule variants, and Hi-Lo counting. Read the play, then drill it in the app until the pause is gone.
TwentyOne is an educational trainer. It does not involve real money. Correct strategy reduces the house edge; it does not eliminate it.
Blackjack insurance pays 2:1 if the dealer has a ten-value card under an Ace. For a basic-strategy player, the math says decline it—including even money.
The running count tracks Hi-Lo tags as cards are exposed. The true count adjusts that number for decks remaining, making the same count comparable at different points in the shoe.
Surrender looks like giving up, but in the right blackjack hands it saves money. Learn exactly when basic strategy says to surrender—and when it doesn’t.
A 3:2 blackjack pays $15 on a $10 bet; 6:5 pays only $12. That small-looking difference adds roughly 1.4 percentage points to the house edge, all else equal.
Doubling is one bet, one card, and the highest-EV press in basic strategy. Here is when to double hard totals and soft hands — and when the table rules move the cell.
Hi-Lo assigns +1, 0, or −1 to each rank, then keeps a running count. It is a memory drill with a purpose — not a promise that the shoe is yours.
A soft total can still take a card without busting. That option is why Ace-7 is not the same decision as hard 18.
Always split Aces and eights. Never split tens. The rest depends on the upcard — and on whether you can double after split.
Whether the dealer hits or stands on soft 17 looks like a footnote. It moves several doubles and surrenders — and it is printed on the table for a reason.
Rows are your hand, columns are the dealer upcard, and the letter in the cell is the play. Here is how to use a chart without freezing at the table.
Basic strategy is the chart of highest-EV plays for every hand versus every dealer upcard. Here is what it is, what it is not, and how to actually learn it.
TwentyOne on iPhone
Instant feedback on every decision, a full basic-strategy chart for your rules, and Hi-Lo drills when you are ready to count.
