Why can I lose a bonus even when the expected value is positive?

Expected value is an average that assumes you complete the entire rollover. Slot variance means a cold streak can drain a small balance before you finish wagering. This simulator estimates your probability of surviving to clear the rollover, which EV alone ignores.

Does betting smaller per spin help me clear a rollover?

Yes. Smaller bets relative to your balance lower variance per step, raising the probability you survive long enough to complete the wagering requirement, even though the expected value is unchanged.

Slot Variance & Bust Probability Simulator

Monte Carlo Variance Engine

Will you survive the rollover?

EV tells you the average conversion — but averages don't get cashed out, you do. Slot variance can bust a small balance long before you finish wagering. This runs thousands of simulated wash attempts to estimate your real probability of clearing the rollover and the spread of outcomes you'd actually see.

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Simulation Inputs

Pull RTP and the target from the bonus terms

Starting Balance ($SC)

Balance you start the wash with

Wagering Target ($SC)

Total turnover = balance × playthrough ÷ weight

Bet Per Spin ($SC)

Smaller bets survive longer

Game RTP (%)

Return to player

Game Volatility

Which option should I select?

Micro-Variance: Blackjack, Roulette, Baccarat, low-risk table games.
Low: Low-max-win slots (<1,000x like Starburst or Blood Suckers).
Standard: Standard slots with 1,000x to 5,000x max wins (e.g. Gonzo's Quest).
High Variance: High-volatility slots (5,000x to 10,000x like Book of Dead).
Mega-Variance: Megaways, jackpot slots, or slots with **>10,000x max wins**.

💡 Pro-tip: High max win = high bust risk. Pick Low to minimize variance.

Higher volatility = wider swings, higher bust risk

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About this model

This is an SD-accurate educational model (per-spin returns calibrated so the average equals your RTP and the swing size matches the volatility class). It is not a per-title paytable, so exact hit frequencies are approximations. The bust-vs-clear odds and outcome spread are what matter here.

Clear the rollover —

Bust first —

Median cash-out —

Avg outcome —

Outcome Distribution

Busted Cleared

P10 (unlucky)—

P50 (median)—

P90 (lucky)—

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Sensei's Verdict

Set your inputs and run the simulation.