On this page (9 sections)
Play money only — read this first
This simulator runs on play money only. It cannot predict a real roll, results here cannot be transferred to any account, and no target position or betting pattern overcomes a negative expected value. It exists to prove one thing clearly: the slider changes variance, never the edge.
Play the simulator
This Dice simulator models a roll-under bet: pick a target between 1 and 98, and you win if a random roll between 0 and 100 lands below it. Win chance and payout multiplier update live as you move the slider, all in play money.
Move the slider, then roll.
The formula behind the payout multiplier
Roll-under dice is roll a random number between 0 and 100 and win if it lands below your chosen target. Win chance is simply the target itself, expressed as a percentage. The payout multiplier this simulator computes is:
multiplier = (100 − edge) / target
Both edge and target are percentages here. Set a target of 50 with a 1% edge and the multiplier is 99/50 = 1.98x. Set a target of 10 with the same edge and it becomes 99/10 = 9.9x — a much bigger multiplier for a much rarer win.
The expected value never changes
Expected return per unit staked is win chance multiplied by payout: (target/100) × (100−edge)/target = (100−edge)/100 = 1 − edge/100. The target cancels out entirely — it cannot appear in the final answer, which is the algebraic proof that moving the slider never changes your expected return at a fixed edge.
Why the edge never moves, whatever the target
Drag the target from 5 to 95 and watch the win-chance and multiplier readouts swap places completely — a rare, big win becomes a frequent, small one. What never changes is the product of the two. That is the cleanest demonstration on this site of the difference between variance (how spread out outcomes are) and house edge (the fixed average cost of playing), because dice isolates the two so completely.
Batch mode: proving it across a thousand rolls
Click “Run 1,000 rolls” at any target and the simulator plays thirty, sixty or ninety-five percent win chances instantly, using the exact same starting bankroll and bet size each time, and reports where the bankroll ends up.
Try the same edge at three different targets
Set the edge to 1% and run the batch at target 10, then target 50, then target 90 — reset the session between runs. All three will land the final bankroll in a broadly similar range over a thousand rolls, even though the win rate reported for each run looks completely different.
How to use this without fooling yourself
Four ways to get something real out of a play-money roll
- Roll manually a few times at the default 50 target and watch the win-chance readout.
Where people trip up: Getting comfortable with the live numbers before touching the slider makes the next step easier to interpret.
- Drag the target to 10, then to 90, watching only the multiplier number.
Where people trip up: The multiplier swings from roughly 10x down to close to 1x — seeing that range in one motion is the fastest way to feel how much the slider trades win size for win frequency.
- Run the batch mode at both extremes with the same edge input.
Where people trip up: Comparing the two final bankrolls directly is more convincing than any explanation of why the edge stays fixed.
- Change only the house-edge input and re-run the same target.
Where people trip up: This isolates the one number that actually controls your long-run expectation, separate from anything the slider does.
Dice simulator vs. real-money dice
| This simulator | Real-money dice | |
|---|---|---|
| Funds at risk | None — play money only | Real deposited funds |
| Payout formula | (100 − edge) / target, shown in full above | Same general shape; exact operator edge not published as a fixed figure |
| Fairness verification | Not applicable — no real wager exists to verify | Provably fair server-seed verification, checkable per roll |
| Purpose | Teach the maths behind variance and edge | Real wagering with real risk and real rakeback accrual |
The code to try it for real:
Honest pros and cons of practising here
What works about this offer
- Zero financial risk while you learn the cleanest edge-and-variance formula on the site
- The entire payout mechanic is a single visible ratio, nothing hidden
- Batch mode proves the fixed-edge claim across a thousand rolls in seconds
- Useful groundwork before the more complex maths in Crash and Plinko
What to weigh up first
- Doesn't quote any specific operator's real published house edge
- A winning batch run here proves the formula, not that a real session will match it
- Cannot replicate the psychological pull of a real balance moving with each roll
- Provably fair verification does not apply, since no real wager exists to verify
Licence, geo-restrictions and playing safely
Licensing. Access is blocked in a number of countries and US states, and the list is maintained by the operator rather than published as a stable document. The current restricted list and licence details live on the operator’s own terms page — read them before you register.
Your side of it. Crypto casinos settle fast, which is exactly what makes them easy to overplay. Before your first deposit at Rainbet, set a deposit cap and a session timer in the account settings — not in your head.
- Deposit limits and self-exclusion tools live in account settings, not support chat
- A losing session is not a signal to raise the stake — it is a signal to stop
- Bonus turnover targets are not a reason to keep playing past your limit
- Free, confidential help: BeGambleAware and Gambling Therapy
Frequently asked questions
How is the payout multiplier calculated in this simulator?
Multiplier equals (100 − edge) / target, where target is your roll-under number as a percentage and edge is the house-edge input above, also a percentage. Move the target and the multiplier recalculates instantly using the same formula every time.
Why does a low target pay so much more per win?
Because win chance and target are the same number here — a target of 5 wins 5% of the time, so the payout has to be roughly twenty times the stake for the long-run maths to balance at your chosen edge. A target of 95 wins 95% of the time and pays close to even money for the same reason in reverse.
Does moving the slider ever change the house edge?
No. The house-edge input is a separate number you control directly; the target slider only trades win frequency against payout size along the curve that edge defines. Every target position produces the identical expected return per unit staked.
What does the batch mode actually prove?
It runs a thousand rolls at your current target and edge instantly, then reports the observed win rate and where a fixed starting bankroll ends up. Run it at a very low target and a very high target with the same edge, and the final bankrolls will land in the same general range despite completely different win rates along the way.
Is roll-under dice provably fair when played for real?
At most crypto casinos, yes — the roll outcome is derived from a server seed committed before you bet and revealed afterward, so it can be checked independently. See our provably fair explainer for the general verification method.
Can I find a target that beats the edge by testing enough combinations here?
No. Every target in this simulator uses the identical formula and the identical edge input you set — there is no hidden favourable target, because the formula guarantees the same expected value at every point on the slider.
Why is dice often called the most transparent casino game?
Because its entire payout mechanic is one visible ratio — win chance in, multiplier out, edge as the only adjustable constant. Mines, Crash and Plinko all encode the same underlying principle, but dice is the one where you can see the whole formula in a single line.