Double Down

LEARN

A plain-language handbook for blackjack and card counting. Read it top to bottom, or jump straight to a section.

Contents

Blackjack in Two Minutes

The goal

Beat the dealer. That's it. You win by holding a hand closer to 21 than the dealer's, or by still standing when the dealer goes over 21 ("busts").

You are not trying to "get 21." You are trying to beat one specific opponent who has to follow fixed rules. That difference drives every good decision in the game.

How a round works

You place a wager, then you and the dealer each get two cards. Both of yours are face up; the dealer shows one card and hides the other.

You act first: take more cards ("hit") or keep what you have ("stand"). If you go over 21, you lose immediately. When you finish, the dealer reveals the hidden card and draws by rule until reaching at least 17.

How rounds end

Closer to 21 than the dealer: you win your wager. Dealer closer: you lose it. Same total: a "push" — your wager comes back.

An ace plus a ten-value card as your first two cards is a "blackjack" and pays extra: 3 points for every 2 wagered.


Card and Hand Values

Card values

Number cards are worth their number. Jack, queen, and king are each worth 10 — so a third of the deck is "tens."

Aces are special: they count as 11 when that helps you, and 1 when 11 would bust you. The ace decides for itself, always in your favor.

Soft and hard hands

A hand with an ace counting as 11 is called "soft." Ace + 6 is a soft 17: hit it and draw a 9, and the ace simply drops to 1 — now a hard 16. A soft hand can never bust on one card.

A "hard" hand has no ace, or an ace already forced down to 1. Hard 16 is the game's most fragile spot: nearly half the deck busts it.

Why it matters

Soft hands let you take risks that hard hands can't afford. The correct play for soft 17 (hit or double) is completely different from hard 17 (always stand). Strategy charts split into hard and soft tables for exactly this reason.


Hit, Stand, Double, and Split

Hit and stand

Hit takes one more card; you can keep hitting until you stand or bust. Stand ends your turn.

The tension: hit too much and you bust; stand too early and the dealer's forced drawing usually gets to 17-21. Basic strategy resolves this tension mathematically for every situation.

Double down

Doubling doubles your wager, but you get exactly one more card — no more decisions. It's an attack move for when you're favored: totals of 10 or 11 against a weak dealer card, where one card likely makes a strong hand.

At this table you can double on any first two cards, including after a split.

Split

When your first two cards match in value, you can split them into two separate hands, each with its own wager equal to your first. Each hand then plays out normally.

Two rules of thumb the strategy chart will confirm: always split aces and eights; never split tens or fives. Split aces are special — each gets exactly one card, and 21 after a split is a regular 21, not a blackjack.


Dealer Rules

The dealer is a robot

The dealer never decides anything. With 16 or less: draw. With 17 or more: stop. At this table the dealer stands on ALL 17s, including soft 17.

Because the dealer's play is fixed, you can compute exactly how often each up-card leads to each final total. Basic strategy is that computation, done for you.

Weak and strong up-cards

A dealer showing 2-6 is "weak": they'll often be forced to draw into a bust. That's when you stand on shaky totals and double aggressively — let the dealer take the risk.

A dealer showing 7-ace is "strong": their most likely finish is 17+. Against strength, you keep hitting risky totals because standing on 12-16 usually just loses slowly.

The peek

When the dealer shows an ace or a ten-value card, they immediately check the hidden card for blackjack. If it's there, the round ends before you act — you only lose your original wager, never a double or split. If you also have blackjack, it's a push.


Blackjack and Payouts

The payout table

Win: 1:1 — wager 10, win 10. Lose: your wager is gone. Push: wager returned, nothing gained or lost.

Blackjack — an ace plus a ten-value card as your first two cards — pays 3:2. Wager 10, win 15. It's the best moment in the game and it happens about once every 21 hands.

Why 3:2 is sacred

Real casinos sometimes pay blackjack at 6:5 instead of 3:2. That small-looking change costs a basic-strategy player about four times the house edge of every other rule combined. Learning to check the payout line is the single most practical "casino literacy" skill this game can teach.

Doubles and splits settle separately

A doubled win pays 1:1 on the doubled amount — wager 10, double to 20, win 20. Split hands each settle on their own: one can win while the other loses, and each carries its own full wager.


Basic Strategy

What basic strategy is

For every combination of your hand and the dealer's up-card, one action has the highest expected value. The full set of answers is basic strategy. It isn't opinion or style — it's arithmetic, computed across every possible card that can fall.

Played perfectly at this table, basic strategy shrinks the house edge to roughly half a percent. Played by feel, most people give up ten times that.

The patterns that carry you

Hard totals: 8 or less always hits, 17+ always stands. 12-16 stands against a weak dealer (2-6, except 12 vs 2-3) and hits against a strong one. 11 and 10 are your doubling hands.

Soft totals: soft 19+ stands. Soft 18 doubles against 2-6, stands against 7-8, hits against 9-ace. Lower soft hands hit or double — never stand.

Pairs: always split aces and eights, never tens or fives, and split the small pairs (2s, 3s, 6s, 7s) against weak dealers.

Trust the chart when it feels wrong

Hitting 16 against a 10 feels suicidal; it's correct. Standing 12 against a 4 feels passive; it's correct. The feedback badges at the table grade every decision against the chart — treat each "Inaccuracy" as a flashcard, and your accuracy score becomes a map of what to review.


What Card Counting Is

The idea

A blackjack shoe has a memory. Cards dealt are gone, so the mix of what remains keeps shifting. A deck rich in tens and aces favors you: more blackjacks (paid 3:2), better doubles, and a dealer who busts more. A deck rich in small cards favors the dealer.

Counting is simply keeping score of that shift. Nobody memorizes which cards are gone — they track a single number that summarizes the balance.

What counting is not

It is not a way to win any particular hand — the next card is still random. It is not illegal — it's just thinking — though casinos may ask counters to leave. And it is not a guarantee of profit: the edge it finds is small and drowned in short-term variance.

Card counting does not guarantee winnings. It estimates changes in the remaining deck and does not overcome short-term variance.

Why learn it anyway

It's a genuinely fun mental skill — like touch typing for probability. It makes you understand why the game behaves the way it does. And it turns watching a blackjack table into an active puzzle instead of a slot machine.


The Hi-Lo System

Three groups

Hi-Lo assigns every card one of three values. Small cards 2-6: +1 (good riddance — they helped the dealer). Middle cards 7-9: 0 (barely matter). Tens, faces, and aces: −1 (the cards you wanted are leaving).

Start at 0 when the shoe is shuffled. Add each card's value as it's revealed. That total is the running count.

Reading the number

A positive running count means more small cards have left than big ones — the remaining shoe is rich in tens and aces. Good for you. Negative means the opposite.

The system is balanced: count through a full deck and you land exactly on 0. That's the classic practice drill, and it's what the Count Trainer checks.

Learning to be fast

Speed comes from cancelling: a king and a five together are 0 — skip them as a pair. Practice in the trainer until a full deck takes under a minute, then turn on Learning mode at the table and count along with real deals.


Running Count vs. True Count

The dilution problem

A running count of +6 with five decks still to come is spread thin — barely one extra good card per deck. The same +6 with one deck left is concentrated and powerful.

The running count measures how many extra high cards remain. What you care about is their density.

The conversion

True count = running count ÷ decks remaining. +6 with 3 decks left → true +2. +6 with 1.5 decks left → true +4.

Estimating decks remaining is its own skill. To the nearest half deck is plenty — glance at the discard tray (or this app's penetration meter) and divide.

What true count is for

Each true count point shifts the player's expectation by roughly half a percent. That's what serious players use to size bets and adjust close decisions. In this app it's a learning gauge — watch how the true count swings as the shoe burns down, and how much more violent the swings get near the reshuffle.


Common Myths and Mistakes

"The dealer always has a ten under there"

Only 4 in 13 cards are ten-valued. Assuming a hidden ten makes players stand too early against strong up-cards and miss profitable doubles. Basic strategy already weights the real distribution — no assumption needed.

Cousin myth: "I was due for a win." Cards have no memory of your results. Only the shoe's composition changes, and only counting tracks that.

"That player took the dealer's bust card"

Another player's hit changes which unknown card comes next — but since the cards are unknown, it changes your odds not at all. Third-base decisions, good or bad, have zero long-run effect on your hands.

Same logic kills the "never take insurance… except with a good hand" idea: insurance is a separate side bet on the dealer's hole card, and without a count it's simply a bad one (which is why this table doesn't offer it).

The mistakes that actually cost points

Ranked by damage: taking even-money/insurance offers; standing on 16 v 10 "to make the dealer bust"; not splitting eights against a 10; splitting tens "because the count feels good"; and drifting from the chart after a losing streak.

Every one of these is graded at this app's table. If your Mistake counter is climbing, the culprit is almost certainly on this list.


Glossary

Blackjack (natural)
Ace + ten-value card as your first two cards. Pays 3:2.
Bust
A hand total over 21. An immediate loss.
Double down
Double your wager, receive exactly one more card.
Hard hand
A hand with no ace, or whose ace must count as 1.
Hi-Lo
The counting system used here: 2-6 = +1, 7-9 = 0, 10-A = −1.
Hole card
The dealer's face-down card.
Penetration
How much of the shoe is dealt before reshuffling. This table reshuffles around 75%.
Push
A tie with the dealer. Your wager is returned.
Running count
The current Hi-Lo total since the shuffle.
S17
Table rule: dealer stands on soft 17 (this table).
Shoe
The stack of shuffled decks cards are dealt from — six decks here.
Soft hand
A hand whose ace counts as 11, so it can't bust on the next card.
Split
Turn a pair into two hands, each with its own wager.
True count
Running count ÷ decks remaining. Measures concentration, not just quantity.
Up-card
The dealer's face-up card — the input to every strategy decision.

Card counting does not guarantee winnings. It estimates changes in the remaining deck and does not overcome short-term variance.