Complete Guide to Card Counting in Blackjack — Wong Halves Decision Calculator

What is card counting and why use it?

Card counting is a mathematical strategy that tracks the balance of high and low cards in the shoe. The more tens and aces remain, the higher the player’s advantage. Our online blackjack calculator makes this simple and provides optimal action hints.

How does the decision calculator work?

Enter the cards that have appeared — the calculator computes Running Count and True Count, shows your current Edge, and recommends an action: Hit, Stand, Double, Split, Surrender.

Important: card counting ≠ guaranteed profit

Counting gives a long-term advantage, but short-term variance still exists. For results, you need:

• Discipline — follow the strategy;
• Bankroll management — correct bet sizing;
• Focus — steady play over long sessions.

Rules this calculator assumes

• ✅ 8 decks
• ✅ Dealer stands on all 17 (S17)
• ✅ Blackjack pays 3:2

This covers most live-dealer online tables.

True Count & Edge: estimating your advantage

True Count = Running Count ÷ decks remaining.

Edge is your expected value in percent. Rule of thumb: each +1 TC ≈ +0.5% to edge.

When to take insurance

Take insurance only at TC ≥ +3.

• TC < +3 — insurance is negative EV;
• TC = +3 — roughly breakeven;
• TC > +3 — mathematically justified.

Why decisions change as TC rises

Basic strategy assumes a neutral shoe. As composition shifts, some decisions “flip”:

• 16 vs 10: low TC → Hit, high TC → Stand
• 12 vs 3: low TC → Hit, high TC → Stand
• 10 vs 10: at very high TC, Double can appear
• 9 vs 7: at high TC — Double instead of Hit

Wong Halves system

Wong Halves is one of the most accurate systems while staying resilient to small errors.

Bankroll management: the Half-Kelly approach

For bet sizing we use Half-Kelly — a safer version of the Kelly criterion.

Practical formula: Bet = (Edge × Bankroll) ÷ (2 × 1.3)

Example: Bankroll $10,000, TC = +3 → Edge ≈ 1.5% → bet ≈ $58.

Expected long-term return with correct play: about 0.5–1.5% of turnover.

Choosing online casinos

• Live dealers (Evolution, Pragmatic Play Live);
• Continuous dealing without auto-shuffle after every hand;
• S17 rules, 3:2 blackjack;
• RTP ≥ 99.5% and reasonable betting limits.

How to enter cards correctly

1. Reset the count before a new shoe.
2. Enter all exposed cards: yours, dealer’s, and other players’.
3. Buttons: 2–9; T for 10/J/Q/K; A for Ace.
4. Track aces separately — they affect blackjack probability.

FAQ: common questions