Blackjack simulator and basic strategy trainer

How this blackjack simulator scores RTP

Blackjack's house edge is quoted per initial bet, so observed RTP here is (initial bets + net result) ÷ initial bets. With these rules (6 decks, S17, 3:2, double after split, no resplit, no surrender) perfect basic strategy loses about 0.5% of each initial bet, an RTP near 99.5%.

Results swing a lot. The standard deviation of one hand is about 1.15 bets, so 1,000 hands have a standard error of about 3.6%. Seeing 96% or 103% after one batch is normal; run several batches and the average settles near 99.5%.

The basic strategy chart in short

Basic strategy is the mathematically best play for each total against each dealer upcard, worked out from every remaining card. The trainer uses the standard six-deck, stand-on-soft-17 chart with doubling after splits.

• Hard 17 or more: stand. Hard 13–16: stand against 2–6, hit against 7–ace. Hard 12: stand against 4–6 only.
• Hard 11: double against 2–10. Hard 10: double against 2–9. Hard 9: double against 3–6.
• Soft 18: double against 3–6, stand against 2, 7 and 8, hit against 9, 10 and ace. Soft 19 and up: stand.
• Always split aces and eights. Never split tens or fives. Split 9s except against 7, 10 and ace.

Which rules change the edge

A 6:5 blackjack payout adds about 1.4% to the house edge and is the single worst rule to accept. Dealer hitting soft 17 adds about 0.2%. Being allowed to double after splitting saves about 0.14%, and resplitting aces or late surrender each save a little more. Always check the payout printed on the table before you sit down.

Why following the chart matters

Playing by feel typically costs 1.5% to 2.5% instead of 0.5%. Common leaks are standing on 12 against a 2 or 3, never doubling soft hands and taking insurance. The strategy-followed score counts only your manual decisions, so use it to drill until you hit 100%. Rakeback then cuts the remaining edge further, which is why low-edge games like blackjack pair well with high-rakeback casinos.

How to use the trainer

Press Deal, decide what you would do, then read the hint and act. Double and Split light up only when the rules allow them. Each finished hand goes into the log with your net result. When you want a large sample, auto-play deals 1,000 hands at your bet size using the same chart, without counting towards your strategy score.