TwentyOne: Blackjack Trainer

Drill blackjack basic strategy until it's automatic. Study the full chart, practice by hand type, and master the exact correct play for your table's rules. No ads.

TwentyOne is a clean, focused blackjack basic-strategy trainer. Learn the mathematically correct play for every hand, then drill it until it's second nature — in a calm, minimalist interface with no ads and no clutter.

WHY TWENTYONE Basic strategy is the proven, optimal way to play every blackjack hand. TwentyOne doesn't just show you a chart — it computes the correct play for your exact table rules and helps you commit it to memory through fast, focused practice.

THE STRATEGY CHART • The complete chart for hard totals, soft hands, and pairs • Color-coded for Hit, Stand, Double, Split, and Surrender • Tap any cell to see the expected value behind every option • Recomputes instantly when you change the rules

PRACTICE THAT STICKS • Deal a hand, choose your action, and see the correct play right away • Modes: Random, Hard Totals, Soft Hands, Pairs, and Most Missed • "Most Missed" automatically resurfaces the hands you get wrong • Track your accuracy, streak, and performance by hand type

PLAYS BY YOUR RULES Real tables differ, and so does correct strategy. Configure: • Number of decks (2, 4, 6, or 8) • Dealer hits or stands on soft 17 (H17 / S17) • Double after split, double rules, and late surrender • Resplit aces, hit split aces, and more The chart and every practice answer adjust automatically.

TWENTYONE PRO Take your training further with a single one-time purchase — no subscriptions, no ads: • Expected value on every hand — see the full EV breakdown behind your decision after each practice hand, not just in the chart • Card Counting Trainer — master the Hi-Lo system with four focused drills: – Card Values: flash through the +1 / 0 / −1 tags until they're instant – Running Count: keep an accurate count as cards are dealt – Deck Countdown: race through a full deck down to zero – True Count: convert running count to true count on the fly

Everything else in TwentyOne is free.

MADE TO LOOK GOOD • Minimalist design with crisp, simple cards • Full light and dark mode • Three app icons to choose from • No ads, no accounts, no tracking — works offline for all training

TwentyOne is for study and entertainment. It teaches optimal decision-making and involves no real-money play and no wagering.