40x Bonus Wagering Simulation: Completion Rates and RTP Limits
A reproducible 25,000-trial toy model separates bonus completion, ending balance and profit—and explains why its results are not real-slot cashout probabilities.
A game with 96% RTP does not give a player a 96% chance of completing bonus wagering. RTP supplies a mean return on stakes. Completion depends on the payout distribution, stake size, starting balance and conditions governing when play stops.
To demonstrate the distinction, we ran a reproducible toy simulation. It is not a simulation of a named slot or a measured casino promotion. All results below belong to the explicitly defined model.
The model and its stopping rule
Each attempt begins with 200 units: a hypothetical 100-unit deposit and 100-unit bonus. A 40× requirement on the bonus alone creates 4,000 units of required turnover. Each bet costs one unit and has a 48% chance of a two-unit gross return, or one-unit net gain. Otherwise it returns zero, a one-unit net loss.
The gross mean return is 0.48 × 2 = 0.96 units per unit staked. Play stops when the balance reaches zero or 4,000 bets have been completed. There are no additional fees, caps, deadlines, excluded games or bonus deductions. A balance remaining after completion is fully withdrawable under the model.
How the experiment is reproduced
We used 25,000 attempts and a deterministic pseudo-random generator starting with integer seed 20261013. The generator updates its unsigned 32-bit state using multiplication by 1664525 and addition of 1013904223, then divides by 4294967296 to obtain the next value. Values below 0.48 produce a winning bet.
The full local script and raw results accompany the editorial research files. The same code and assumptions reproduce the counts. Reproducibility checks the experiment; it does not make the toy distribution representative of a commercial slot.
Results of the defined experiment
| Measure | Result |
|---|---|
| Starting attempts | 25,000 |
| Attempts completing 4,000 bets | 17,079 |
| Completion rate | 68.316% |
| Mean final balance among completers | 72.34 units |
| Mean withdrawable balance across all attempts | 49.42 units |
| Mean bets played across all attempts | 3,763.67 |
Completion is defined here as placing all 4,000 bets, including a last bet that leaves zero. There were 15 such zero-balance completions. The remaining 17,064 completions ended with a positive balance: 68.256% of all attempts. Thus 68.316% is a turnover-completion rate, not even the probability of having a positive withdrawal in this model.
Values are rounded for presentation; the raw results retain additional precision. Attempts stopping before the target contribute zero to the all-attempts withdrawable average and are excluded from the completers' average. The 15 zero-balance completions remain in the completion denominator.
Completion is not profit
Completing with a positive balance answers whether the turnover target was reached before exhaustion. It does not answer whether the final withdrawal exceeds the original 100-unit cash deposit.
The reported completers' mean of 72.34 units is an average, not a statement that every completer withdraws that amount or that a particular proportion finishes ahead. The experiment's reported metrics do not include the profit-rate count, so no such percentage is claimed here.
Across all attempts, the mean withdrawable balance is approximately 49.42 units. Relative to the initial 100-unit cash deposit, the model's mean net result is therefore approximately −50.58 units. The starting 200-unit combined balance must not be confused with the amount of cash personally deposited.
Why a fixed-turnover calculation gives another number
If every path could complete 4,000 bets, a 4% expected loss rate gives 160 units of expected wagering loss. Starting at 200 would then give an unrestricted expected final balance of 40.
The actual simulated stopping rule is different: exhausted paths stop early. Average turnover is therefore below 4,000. Its all-attempts final balance is about 49.42 rather than 40. Neither this average nor the survival-conditioned mean can be replaced by the unrestricted formula without changing the model.
What the simulation does not establish
Real slot paytables can contain many payout sizes and feature states. A cashout cap, contribution rate, different stake or non-cashable bonus deduction changes the model. More trials reduce sampling variation in this experiment; they do not supply missing real-game parameters.
The Gambling Commission's RTP guidance concerns an average return, not a withdrawal probability. Do not transfer 68.316% to a real offer merely because its advertised RTP is 96%.
The jurisdictional boundary
In Great Britain, the bonus-funds wagering limit is 10×, with changes effective from 19 January 2026. Our 40× condition is a mathematical scenario, not an advertised compliant British offer.
The useful lesson is how to disclose a model and distinguish its outputs. Before evaluating an actual promotion, replace every invented assumption with verified terms and game data; where that information is unavailable, report the uncertainty instead of inventing a cashout probability.
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