Monte Carlo simulation of blackjack with Basic Strategy, Hi-Lo card counting, and Random play — run up to 1 000 000 hands and watch the house edge converge.
Basic Strategy reduces the house edge to 0.5 % in a 6-deck S17/DAS game — the lowest achievable without counting cards. Hi-Lo assigns +1 to low cards (2–6) and −1 to high cards (10–A); a high true count means more 10s remain, so the counter raises bets. The house edge can flip negative (player advantage) at true counts above +3, explaining why casinos restrict bet spreads and shuffle early.
Select a strategy (Basic, Hi-Lo, or Random), set deck count and penetration, then click Play. The net-units chart shows cumulative profit/loss per hand. The house-edge chart converges toward the true EV as sample size grows — notice how variance dominates early and the line stabilises after ~10 000 hands. The strategy reference table at the bottom shows the optimal move for every player hand vs dealer upcard.
Edward Thorp published "Beat the Dealer" in 1962, proving mathematically that card counting gives a player edge. Casinos responded by adding decks, cutting early, and banning known counters. The MIT Blackjack Team operated from 1979–2000, reportedly winning millions using team-based counting disguised as large-group play — their story inspired the film "21" (2008). Modern casino surveillance uses facial recognition to flag known advantage players before they even sit down.