Play every hand perfectly.
21 Trainer teaches you the mathematically correct play for every blackjack hand, then drills card counting until it is second nature. Instant feedback, clear explanations, zero risk.
Educational tool. No real money gambling.
Dealer shows
Your hand
What is the correct play?
Training demo drawn by this page. Simplified 6-deck chart, dealer stands on soft 17.
Everything you need to play smart
From your first basic strategy chart to pro-level counting drills.
Basic Strategy
See your hand and the dealer's upcard, choose your action, and get instant feedback with a clear explanation for all 270+ hand scenarios.
Card CountingPro
Practice four systems: Hi-Lo, KO, Omega II, and Zen. Single card drills, multi-card speed rounds, true count conversion, and index deviations.
Daily Drills
Daily Challenge keeps your streak alive, Weakness Drill targets the hands you miss most, and Speed Drill puts your decisions on the clock.
Bankroll SimulatorPro
Run full casino sessions with virtual chips, then review your strategy adherence and a hand-by-hand mistake breakdown. No real money, ever.
Charts & House Edge
Color-coded strategy charts that redraw for your exact rules, deviation charts, and a house edge calculator covering 9 real casino presets.
Deep StatsPro
Accuracy heat maps by hand type and dealer upcard, session history, streaks, and 38 achievements that track your progress over time.
Start free. Go Pro when you are ready.
The core trainer is free forever. Pro unlocks the counting suite and simulator.
Free
No account, no ads, no data collected
- Basic strategy trainer with explanations
- Color-coded strategy charts for your rules
- 9 casino presets plus full rule customization
- Accuracy tracking, streaks, and session goals
- Works 100% offline
Blackjack Pro
$2.99/month after a 3-day free trial, or $9.99 lifetime
- Four counting systems: Hi-Lo, KO, Omega II, Zen
- True count, bet spread, and deviation drills
- Bankroll simulator with adherence grading
- Accuracy heat maps and advanced statistics
- Weakness Drill and hand-by-hand review
Billed by Apple. Cancel anytime in your Apple ID settings. Pro does not change the odds in any simulation.
Learn the game, for real
Plain-English guides to strategy, counting, and the math behind blackjack.
Blackjack Basic Strategy, Explained in Plain English
What the chart really is, why it works, and the five decisions that teach the logic behind every cell.
How Card Counting Actually Works
Why high cards favor you, how the Hi-Lo running count and true count work, and the honest limits the movies leave out.
Blackjack House Edge: What Half a Percent Really Means
What half a percent actually measures, how rules like 6:5 move it, and why variance hides it in any single session.
Ready to play perfect strategy?
Important Notice
21 Trainer is an educational and entertainment application designed to teach blackjack basic strategy and card counting techniques.
- This is NOT a gambling application
- No real money is wagered, won, or lost at any time
- Virtual chips and currency have no real-world monetary value and cannot be redeemed, transferred, or exchanged
- This app does not facilitate, promote, or enable real-money gambling
- Training results do not guarantee performance at real casino tables
- This app is intended for users aged 17 and older
- Practice or success in this app does not imply future success at real money gambling
If you or someone you know has a gambling problem, call 1-800-522-4700 (National Council on Problem Gambling).
