Free Roulette Simulator
Use this free online roulette simulator to generate European, American or triple-zero wheel outcomes from a single spin to large Monte Carlo samples. Test a fixed bet, inspect recent pockets and compare observed hit rate, RTP, streaks and session results with their theoretical values. No download, registration or real-money play is required.
Run the roulette wheel simulator
Choose a wheel, fixed bet, stake, spins per session and number of sessions. The result uses the same inputs on every simulated spin and reports both aggregate and session-level statistics.
Settings from the odds calculator
Applying replaces the main simulator settings and clears the current results, recorded outcomes and system-comparison sample. Download any results you want to keep first. The separate system-comparison rules stay unchanged.
The preview uses 100 fixed-length sessions at 1 unit per spin, without bankroll stops. It does not import a target-hit count or losing-streak question. Results will vary around the theoretical probabilities.
The full fixed stake must be available before a spin. Loss and profit thresholds are checked after settlement and may be overshot. The spin count above becomes a maximum; no top-ups or smaller final bets are made.
Recent simulated pockets
Save and replay the complete run
Keep all outcomes from a completed run, in their original order and separate sessions. JSON saves the settings for exact replay; CSV exports every recorded outcome with a stable pocket ID such as pocket:00. Both include zero-spin sessions. Up to 1,000,000 outcomes are retained; the recent-pocket display above still shows only the last 20.
Run the simulation to make a record available.
Copy or export a segment from one session
Choose a recorded session after running the simulator.
Prediction accepts European/American records of 1–10,000 outcomes. Select a contiguous range, save its journal and load it in the observation journal. Triple-zero records remain available as run JSON, CSV or TXT; the analyzer does not yet support 000. A selected segment is not the complete run. Do not select only favorable stretches to evaluate a claim.
Load a saved run for replay
Choose a file to inspect its settings before replaying.
Replay settles the saved outcomes using the saved fixed bet and stopping rules. It generates no new spins and is not an independent validation sample. Missing outcomes, invalid pockets and records inconsistent with the stopping rules are rejected. Importing a file does not verify where it came from.
Files are processed in this browser, with no automatic save. Download before starting another run, changing the simulation settings, resetting or leaving: those actions clear the current run record. Bankroll-mode files contain only spins actually played, with no invented outcomes after a stop. Comparing different systems requires a separate experiment.
Compare staking systems on the same outcomes
This separate experiment compares flat stakes, Martingale, three-win Paroli, Fibonacci and D’Alembert on one fixed even-money selection. It uses the wheel, spins per session and session count above, with the bankroll and limits below. Each system receives its own identical starting balance for each session.
Amounts: 0.01–1,000,000 units, at most two decimals. Only standard 1:1 settlement is modeled: 0, 00 and 000 are losses. No La Partage, en prison, partial stakes, top-ups or stake capping.
No comparison yet. Fix the rules before generating a sample.
On smaller screens, swipe the tables sideways to see all measures.
| System | Total net | Net versus flat | Total staked | Paid spins | Profitable sessions | Largest drawdown | Observed RTP | Edge-cost reference |
|---|
Net versus flat pairs the same recorded sessions. Profitable means net above zero, not merely a winning bet. Drawdown is the largest peak-to-trough bankroll fall within any one session. Edge cost is actual amount staked × house edge; it is a reference on this realized action, not an exact pre-run expectation. A better result in this sample is not evidence of a profitable system.
All system/session results
| System | Session | Waited | Paid spins | Unconsumed tail | Staked | Gross return | Net | Final bankroll | Max drawdown | Stop reason |
|---|
Load a saved comparison
Choose a comparison file; its origin cannot be verified.
Exact progression and stopping rules
- Flat: stake one base unit every paid spin.
- Martingale: double after a loss; reset to one unit after a win.
- Paroli: stake 1, 2, then 4 units after successive wins; reset after the third win or any loss.
- Fibonacci: use working stakes 1, 2, 3, 5, 8… (starting at the second 1 of 1,1,2…). Move forward one position after a loss and back two after a win. If that move reaches or passes the starting position, the next stake is one unit.
- D’Alembert: add one unit after a loss; subtract one after a win, with a one-unit minimum.
A progression reset starts another cycle; it does not end the session by itself. Choose the next stake from earlier paid results, then check the maximum stake and available funds before revealing that outcome. If both checks fail, the stop is labeled maximum stake. Never reduce a required stake to fit. After settlement, check the profit target, then stop-loss; either can be crossed by the last bet. Thresholds reached on the final spin take precedence over the spin cap.
While waiting, a hit resets the consecutive-miss count. The Nth miss is observed without a bet. After entry there is no further waiting; only paid results update the progression. All systems begin from one unit and reset their state at the next session. Unconsumed outcomes stay in the common record for other systems; no system borrows another system’s balance.
Fresh comparison generation creates full common sequences before settlement. Reusing the saved run above requires fixed-count mode with every requested outcome present; funded-mode records are rejected because they may omit a future tail. Changing comparison rules clears its results but keeps its sample for explicit reanalysis. Starting/changing the main simulator clears the comparison. Save JSON before leaving; there is no automatic storage.
Retuning on the same sample is an in-sample experiment, not independent validation. After fixing rules, generate fresh sessions to check them. Waiting and stake progressions do not make a fair independent outcome due; see the mathematical discussion of betting systems.
Bankroll and session stops
Every row starts from the same bankroll. Zero-spin sessions are included in the session summary but have no observed hit rate or RTP. A stop reason records why this session ended, not a forecast of the next run.
Scroll the table horizontally on a narrow screen to see the final bankroll and stop reason.
| Session | Spins played | Total staked | Gross returned | Net result | Final bankroll | Stop reason |
|---|
Distribution of session results
See how many sessions finished in each net-result range. Net result is all returns minus all stakes for one session.
Range endpoints are inclusive. Fixed-count mode groups possible fixed-bet results; bankroll mode groups final balances relative to the starting bankroll in cent-sized intervals. An interval can include unobserved values. Percentages describe this sample, not the probability of a future session.
Free online roulette simulator for practice and probability
This is a mathematical roulette simulator rather than a real-money casino table. You can spin once for a quick result, run a longer European, American or triple-zero wheel sample, or split the same settings across many independent sessions to compare variance.
For table formats and zero rules at real tables, compare the roulette casinos reviewed on this site. The simulator models probabilities and payouts; it does not reproduce an individual casino game.
The main simulator keeps the selected stake fixed on every spin. That makes observed hit rate, payout, RTP and session distribution directly comparable with the exact model. It is useful for practicing how roulette probabilities behave without deposits, downloads or claims that recent outcomes predict the next pocket.
What the roulette simulator measures
The tool generates a complete sequence of wheel pockets, resolves the selected fixed bet and records wins, losses, gross return and net result. When multiple sessions are selected, each session is measured separately before the results are combined. The separate system-comparison panel below tracks changing stakes and independent bankrolls; the roulette strategy overview compares their bankroll and table-limit risks.
Observed hit rate and RTP describe the generated sample. The theoretical values come from the wheel and payout table and do not change when a new sample happens to perform well or badly.
The most useful comparison is not whether one session won. It is how widely repeated sessions vary around the same expected value.
Exact probability and simulation answer different questions
An analytical calculator gives the exact probability before any spins are generated. The roulette odds calculator provides those one-spin, exact-hit and repeated-spin results, while a simulation shows one possible realization of the same probability.
For example, red covers 18 of 37 pockets on a European wheel, so its exact hit rate is 48.65%. A simulated block of 100 spins may finish above or below that value without changing the next-spin probability.
Running more spins generally narrows proportional variation, but it does not force every session to finish close to the theoretical result.
A hit and a profitable session are different
With two European red bets of 1 unit, two wins finish at +2, one win and one loss finish at 0, and two losses finish at −2. The probability of finishing ahead is (18/37)² = 23.67%. A break-even session is not counted as profitable.
Session distribution
These statistics summarize the net result of each independent session. A wide best-to-worst range is normal when the number of spins per session is limited.
In fixed-count mode, one session of 100,000 spins and 100 sessions of 1,000 spins create the same total action at the same stake. They have the same aggregate expected net, but their session distributions differ. Streaks restart at each session boundary. “Spin once” starts a fresh one-spin run; it does not extend the previous sample. In bankroll mode it also resets the starting balance and checks whether that one stake can be funded.
When a funded session stops
- Before the spin: the balance must cover the full stake. A smaller remaining balance is kept, but no partial bet is placed.
- After settlement: check the net profit target, then the stop-loss measured from the starting bankroll. A threshold can be crossed by the last settled bet.
- At the spin cap: end the session if neither threshold has been reached. A threshold reached on that last spin takes precedence. Insufficient funds is checked only if another spin is due.
Each independent session receives its own starting bankroll. Stops change the amount actually wagered and the distribution of final balances; they do not change the next-spin probability. Zero-spin sessions count as break-even in the session summary and are identified separately in the bankroll table.
| Measure | Value | Meaning |
|---|---|---|
| Mean session net | — | Average result across the simulated sessions. |
| Median session net | — | Middle result after sessions are ordered. |
| Standard deviation | — | Spread of session-level net results around their mean. |
| Profitable / break-even / losing | — | Count of sessions in each final-result category. |
Largest pocket deviations in this run
The table shows the ten pockets with the largest absolute difference between observed and expected counts. These are random deviations within the current simulation, not hot-number predictions. With early stopping, the comparison count is the model rate multiplied by actual spins: it is a descriptive reference, not an expectation conditional on that stopped sample or a significance test.
| Observed count | Expected count | Observed share | Difference | |
|---|---|---|---|---|
| Run the simulation to populate pocket statistics. | ||||
Why short simulations can beat theoretical RTP
RTP is a long-run weighted average, not a ceiling on individual sessions. A short sample can include more winning pockets than expected, unusually well-timed high-payout hits or a long run without a win.
Observed RTP can therefore exceed 100% or fall to zero in a small run. Neither result changes the published payout ratio or the expected value of the next independent spin. The roulette fairness guide explains why an unusual sample is not enough to establish manipulation.
Increasing the number of simulated outcomes makes extreme proportional deviations less common, while the expected dollar or unit loss continues to grow with total action.
Why more spins do not remove the house edge
For a fixed amount of planned action, expected loss is that amount multiplied by the house edge. More spins may make the observed percentage move closer to theoretical RTP, but they also increase the total stake exposed to the edge. The roulette RTP calculator isolates that theoretical return and expected-loss calculation without random sampling.
A European straight and a European even-money bet have different volatility, yet both retain the standard 1/37 expected loss per unit wagered. American first five is an exception with a larger 3/38 edge. On the 39-pocket model, the standard bets offered here have a 3/39 edge; special zero-area paytables are outside this simulator. See the triple-zero rules and payout models for those distinctions.
Fixed-count expected net = planned total wagered × (theoretical RTP − 1) Stopped-run edge-cost reference = actual total wagered × (theoretical RTP − 1) Observed RTP = simulated gross return / simulated total wagered Observed result is a sample; theoretical RTP is the modelReading results after an early stop
The amount wagered in bankroll mode depends on the generated outcomes. Its edge-cost reference is not an exact pre-run expectation for a funded session. For this bounded fixed-stake model, expected net equals minus the house edge times expected action across repetitions, not the action from one selected run. Observed RTP is gross returned divided by actual total staked; it is unavailable when no bets were placed. Stopping rules do not turn a negative-edge bet into a profitable expectation.
How browser randomness is generated
The roulette simulator uses crypto.getRandomValues() from the browser Web Cryptography API. It converts random 32-bit values into 37, 38 or 39 equally sized outcomes with rejection sampling, avoiding the small distribution bias caused by a direct modulo operation.
This implementation is suitable for an educational variance demonstration. It is not a certified casino RNG, does not reproduce a particular operator's software and should not be used to audit a gambling product. It also contains no physical equipment state; the roulette wheel-bias guide covers wheel-specific mechanical and statistical evidence separately.
Regulated gaming standards require much more than a browser demonstration, including distribution, independence, unpredictability, source-code and operational testing.
Simulation, history analysis and prediction
The roulette simulator generates new model outcomes, while the roulette spin-history analyzer describes results that have already been recorded. Neither process reveals the next independent pocket.
| Tool | Input | Output | Next-spin prediction? |
|---|---|---|---|
| Exact odds calculator | Wheel, bet and spin count | Analytical probabilities | No |
| Roulette simulator | Model settings and random generation | One or more possible samples | No |
| History analyzer | Recorded past outcomes | Descriptive frequencies and screening tests | No |
| Current-spin physical model | Position, velocity and acceleration | Landing-region estimate under controlled conditions | Different data and method |
A favorable run does not identify a winning system, a due number or a predictable next outcome. Treat gambling as paid entertainment and set monetary and time limits before playing.
Common questions about roulette simulation
Why does the roulette simulator give a different result each time?
Run simulation generates a new independent random sample. Different wins, streaks and net results are expected even when every input and theoretical probability remains unchanged. Replay this run instead recalculates the saved sequence with its saved settings, so it repeats the same results.
Can simulated RTP be higher than 100%?
Yes. Observed RTP measures one finite sample, so a profitable run can exceed 100%. Theoretical RTP remains below 100% for the standard bets modelled here.
Does a million simulated spins prove what will happen in a casino?
No. It illustrates the mathematical model and sampling variation. It does not certify a casino implementation, reproduce physical wheel conditions or forecast a future session.
Why can more spins produce a larger expected loss?
More spins increase total amount wagered. Even when observed RTP becomes proportionally closer to its theoretical value, the house edge is applied to a larger volume of action.
Does the simulator use Math.random()?
No. It requires the browser Web Cryptography API and uses crypto.getRandomValues() with rejection sampling. New random generation stops with an error if that API is unavailable. Saved-run replay does not need fresh random numbers.
Technical references
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