run the slots
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run the slots
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Enter the current accumulator value and reset point to calculate expected value, return percentage, and whether this mystery bonus is worth playing right now.
Mystery bonuses are accumulators built into slot machines that award a jackpot at a randomly selected threshold between a floor value and a ceiling. Games like Buffalo Link, Dragon Link, and Lightning Cash use this mechanic. The accumulator climbs with every bet until it triggers — which means the higher it climbs past the floor, the better the expected value for the next player to sit down.
About the Contribution Rate
The contribution rate is the percentage of each wager added to the accumulator. Most games run between 1.5% and 3%. If the ceiling is displayed on the machine, entering it improves accuracy — otherwise the calculator estimates it from the current and reset values.
Enter values to see verdict
Game Presets
Inputs
Current accumulator reading.
Value it resets to after triggering.
Your wager per spin.
Max accumulator value, if known. Leave blank to estimate.
% of each bet added to the accumulator. Usually 1.5–3%.
Estimated RTP of the base game (excluding the mystery bonus).
Enter the current accumulator value and the reset value. The calculator estimates the statistical midpoint where the mystery bonus is likely to trigger, then factors in your coin-in cost and base game return to give you an expected value.
Contribution Rate is the percentage of each wager added to the accumulator. Enter the ceiling if it's displayed on the machine — otherwise the calculator estimates it from the current and reset values.