Model Assumptions

The simulator focuses on single-line bets without odds. Each round represents a full resolution of the selected wager. For multi-roll bets such as the pass line, the code models the come-out roll, establishes a point when necessary, and continues rolling until the bet wins or loses. Proposition bets resolve in a single roll. When a don't pass or don't come bet rolls a 12 on the come-out, the program treats it as a push and repeats the come-out until the wager resolves.

A session ends early if the bankroll cannot cover another full wager. This mimics a player who flat bets at a fixed size and walks away when the bankroll runs out. Free odds, pressing strategies, and place bet buy commissions are not included, keeping the focus on the intrinsic volatility of the base wagers.

Interpreting the Results

The summary reports the chance of finishing ahead, breaking even, or busting based on the number of simulated sessions. It also calculates the mean and standard deviation of ending bankrolls and highlights the best and worst runs observed. Use the sample trajectory to inspect how the first simulated session evolved roll by roll.

Because craps results are highly variable, rerunning the simulation can produce slightly different percentages. Larger sample sizes reduce noise but take longer to compute. Stick within the preset limits for smooth performance in your browser. For a deeper dive, export the summary with the copy button and log multiple experiments with different bet sizes or bankrolls.

Responsible Play Reminder

No simulator can erase the house edge. Even low-edge bets experience significant downswings, which is why bankroll management and stop-loss rules are important. Consider pairing this tool with the house edge explorer to choose wagers that align with your risk tolerance. Treat the outputs as educational insight rather than a guarantee of future results.

How the Simulation Works

For each session the program iterates through the specified number of rounds or until the bankroll is exhausted. In every round it calls a resolver function tailored to the selected bet. These resolver functions roll virtual dice with JavaScript’s pseudorandom generator, apply the rules of craps to determine a win, loss, or push, and return the net change to the bankroll. Accumulating these changes produces a bankroll trajectory. After repeating the process across hundreds or thousands of sessions, the simulator aggregates ending balances to estimate the distribution of outcomes.

Key Metrics Explained

The profit probability metric tells you how often the bankroll finished above the starting amount. The risk of ruin shows the proportion of sessions where funds hit zero before all rounds completed. Standard deviation quantifies how widely the ending balances spread around the average—a higher value indicates larger bankroll swings. The best and worst session summaries reveal the extremes you might encounter in real play, helping you plan for emotional highs and lows at the table.

Experimenting with Strategy

Try adjusting the bet size relative to the bankroll to understand volatility. A conservative $10 pass line bet on a $500 bankroll rarely busts, while a $50 Any 7 wager on the same bankroll evaporates quickly. You can also compare bet types by keeping bankroll and stake constant. Switching from pass line to hardways demonstrates how the house edge manifests as larger risk-of-ruin percentages. After running a scenario, copy the results and paste them into a spreadsheet to track how different strategies perform.

Reading the Sample Trajectory

The trajectory log prints every round of the first simulated session. Positive numbers indicate wins, negative numbers losses. Points of interest such as a streak of consecutive losses or a large proposition win stand out. Use this feed to visualize how quickly short-term variance can swing a bankroll. If you see too many heart-stopping dips, consider reducing your bet size or opting for wagers with smaller house edges.

Limitations and Next Steps

The simulator assumes each session is independent and does not model table minimum changes, dealer errors, or betting progressions. It also uses JavaScript’s built-in random number generator, which is sufficient for educational purposes but not certified for gaming. Advanced players might extend the code to include free odds, hedging bets, or dice control hypotheses. Until then the tool serves as a transparent sandbox to explore the probabilistic nature of craps and to reinforce that even “safe” bets can experience dramatic swings.