Stay and the Mathematics of Australian Online Casino Games
If you want to understand what actually happens to your money on Stay, you have to think in terms of expected value rather than luck. Probability theory does not care about hot streaks or cold dealers. It only cares about the house edge and the number of rounds you play. The following checklist walks through the maths of the Stay service at https://stay-casino-au.net/ , using Australian dollars, concrete formulas and worked examples. Treat every number below as a tool, not a promise.
Stay Expected Value in Plain Numbers – The Core Formula
Expected value (EV) is the average result you would get if you repeated a bet an infinite number of times. For a single wager of amount B with win probability p and payout odds of d to 1, the formula is:
EV = B x (p x d – (1 – p))
If EV is negative, the operator keeps a slice on average. If it is positive, the player profits over the long run. On Stay, as on any regulated Australian operator, every standard game carries a negative EV, which is the mathematical definition of the house edge. The size of that edge is what separates a good choice from a poor one.
A quick sanity check. A coin flip paying 1 to 1 has p = 0.5 and d = 1, so EV = 0. A coin flip paying 0.95 to 1 gives EV = 0.5 x 0.95 – 0.5 = -0.025, or -2.5 percent. That 2.5 percent is the house edge in its simplest form.
Calculating the Stay House Edge from Published RTP
Return to player (RTP) is published as a percentage and is directly linked to the house edge by one subtraction:
House edge = 100 percent – RTP
So an RTP of 97.30 percent means a house edge of 2.70 percent. Over 1,000 bets of AUD 1 each, the expected loss is 1,000 x 1 x 0.027 = AUD 27. Over 10,000 such bets, it is AUD 270. The variance narrows as the sample grows, which is why the law of large numbers matters more than any single session.
Below is a reference table of typical RTP bands you will encounter in the Stay game library.
| Game category | Typical RTP | House edge | Expected loss per AUD 1,000 wagered |
|---|---|---|---|
| Blackjack with basic strategy | 99.50 percent | 0.50 percent | AUD 5.00 |
| European roulette | 97.30 percent | 2.70 percent | AUD 27.00 |
| Baccarat banker bet | 98.94 percent | 1.06 percent | AUD 10.60 |
| Classic slots | 96.00 percent | 4.00 percent | AUD 40.00 |
| Video slots | 95.00 percent | 5.00 percent | AUD 50.00 |
| American roulette | 94.74 percent | 5.26 percent | AUD 52.60 |
| Keno | 92.00 percent | 8.00 percent | AUD 80.00 |
The spread between the top and bottom row is more than tenfold. Choosing a game is therefore a mathematical decision, not a matter of taste.
A Stay Variance Checklist for Realistic Bankroll Planning
House edge tells you the average drift of your balance. Variance tells you how far you can deviate from that average in the short term. For n independent bets with win probability p, the standard deviation of your number of wins is:
SD = sqrt(n x p x (1 – p))
For 100 even-money bets at p = 0.5, SD = sqrt(100 x 0.5 x 0.5) = 5. A result of 60 wins is two standard deviations above expectation, unusual but entirely possible. This is why a bankroll plan that ignores variance fails even when the maths is correct.
Use this checklist before you deposit on Stay:
- Estimate the number of rounds you will play in a session.
- Multiply rounds by average bet to get total turnover.
- Multiply turnover by the house edge to get expected loss.
- Multiply expected loss by three to set a variance buffer.
- Ensure your bankroll exceeds that buffer before starting.
- Record actual results and compare them with the prediction.
- Adjust bet size rather than the game category if you want lower variance.
- Recheck the RTP of any game you have not played before.
- Treat any session result outside two standard deviations as an outlier, not a trend.
If your bankroll is AUD 300, your expected loss is AUD 20 and your buffer is AUD 60, you have AUD 240 of room. That is a mathematically defensible starting point.
Why Stay Bonus Terms Change the Effective Edge
Bonus funds and free spins alter the effective house edge because they attach a wagering requirement. Suppose Stay offers a AUD 100 bonus with a 30x wagering requirement on a game with a 4 percent house edge. The total turnover needed is 100 x 30 = AUD 3,000, and the expected cost of clearing it is 3,000 x 0.04 = AUD 120. The bonus is therefore worth less than its face value once the requirement is applied.
Run the same calculation with a lower-edge game. At 1 percent, the expected cost falls to AUD 30, and the bonus becomes genuinely valuable. The formula is always:
Net bonus value = Bonus – (Wagering requirement x Bonus x House edge)
This single equation explains more about bonus economics than any marketing page. Read the terms, plug in the numbers, and the answer is unambiguous.
Stay Odds, Payouts and the Cost of Inefficient Bets
Some bets look attractive but fail the EV test. A single number in European roulette pays 35 to 1, yet the true probability of hitting it is 1 in 37. The EV per AUD 1 bet is:
EV = 1 x (1/37 x 35 – 36/37) = -0.027
That is the same 2.70 percent edge you get on any other European roulette bet. The payout structure is fair within the game, but the game itself is priced at a fixed edge. In blackjack, by contrast, basic strategy can push the edge below 1 percent, which is why the same AUD 1,000 turnover costs AUD 5 instead of AUD 40.
- Check the RTP before you play, not after.
- Prefer games with published and audited return figures.
- Avoid side bets with undisclosed odds.
- Treat every bet as a single EV calculation.
- Compare turnover cost across game categories.
- Use the bonus net value formula before opting in.
- Keep a written record of actual versus expected results.
Stay and the Law of Large Numbers in Practice
The law of large numbers states that as the number of trials increases, the observed average converges to the expected value. In a 100-round session, deviations of 20 percent are common. In a 100,000-round sample, deviations shrink toward 0.1 percent. This is not a reason to play longer, it is a reason to understand why short-term results are noisy and long-term results are predictable.
For Stay users in Australia, the practical takeaway is straightforward. Compute the expected loss per session, size your bets so the variance buffer holds, and judge every promotion by its net value after wagering. The arithmetic is simple, the discipline is the hard part, and the numbers never negotiate.