Blackjack Odds: 21 Trainer
Card Counting & Basic Strategy
Only for iPhone
Free · Designed for iPhone. Not verified for macOS.
iPhone
Every other blackjack trainer tells you that you were wrong. This one tells you exactly what it cost, worked out live from the cards still in the shoe.
Every other blackjack trainer tells you that you were wrong. This one tells you what it cost.
Hit 16 against a ten when you should have stood, and you will see the exact figure — 8.9¢ for every dollar on the table — worked out live from the cards still in the shoe, not looked up in a table.
STRATEGY YOU CAN CHECK
The chart in this app is verified square by square against a solver that derives correct play from first principles. All 340 squares, under both soft-17 rules, on every build. Nothing is typed in and hoped for.
LEARN
A guided path through the chart in eight lessons, in the order the rules actually build on each other. Start at the easy totals, finish at the fiddliest pairs, and collect the stars on the way.
DRILL
Rapid-fire hands with instant feedback and the real cost of every miss. Filter by hard totals, soft hands, pairs, stiffs, or just the squares you keep getting wrong. Sixty-second sprints when you want pressure.
PLAY
A full six-deck table with bankroll, splits, doubles, insurance and surrender. Live expected value on every button, or switch it off and test yourself.
COUNT
Hi-Lo from the ground up: running count drills at four speeds, true-count conversion, and the Illustrious 18 and Fab 4 index plays.
CHART
The full strategy chart, tap any square for the reasoning and the live odds. Turn on the mastery overlay and watch it fill with gold as you learn.
THE COST LEDGER
Your mistakes, totalled. Measured against the 0.55% the house takes from perfect play, so you can see exactly how much of your disadvantage is self-inflicted.
No accounts, and nothing leaves your phone.
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The developer, Blubuilds LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Blubuilds LLC
- Size
- 2.7 MB
- Category
- Casino
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
13+
- 13+
- Infrequent
Simulated Gambling
- Copyright
- © 2026 Blubuilds LLC