Every slot has a design document, the PAR sheet, that fixes how much it pays back over the long run and how wildly it swings. The same-looking game can be ordered anywhere from 85% to 96.2% payback, and cruise lines don't publish their holds, so assume ship slots hold at least as much as land casinos (Nevada's 2025 average was about 7.13%).
A cruise is a small sample: over about 6,000 spins on Double Diamond Deluxe, the likely range runs from about 79% to 106% payback, so plenty of players finish ahead and plenty lose far more than the hold suggests. Video poker is the exception, because its pay table tells you the return, which is why lines earn it more slowly. Table-game edges come straight from the rules.
Jump to the calculator: how long will my money last?Range of likely resultsJackpot odds
Terms with a dotted underline are explained when you tap or select them.
What's on a PAR sheet
Slot makers give casinos a Probability Accounting Report, or PAR sheet, for every game. Researchers Kevin Harrigan and Mike Dixon got PAR sheets for games in use in Ontario through a freedom-of-information request, and Sheryl Ashley, a risk consultant at the CPA firm Egghart LLC, explains how casinos use them. Four numbers matter most.
Payback %
The share of money wagered that the game returns over the long run. A 92% game pays back $92 for every $100 played, on average.
Hold %
The casino's share: 100% minus payback. That 92% game holds 8%. It's the slot version of the house edge (The casino's built-in advantage: the share of each bet it expects to keep over the long run. For slots it's called the hold.), and it's what drives your theo (Theoretical loss: what you're expected to lose on average, worked out as amount wagered × house edge. Casinos base comps on it, not on what you actually lose.).
Hit frequency
How often a spin wins anything. In the PAR sheets it ranged from 4.9% per line (the 85% version of Lucky Larry's Lobstermania) to 16.7% (Money Storm).
Volatility index
How far real results can stray from the payback %. The bigger the number, the bigger and rarer the wins, and the wider the swings.
Same game, different price
Casinos can order the same game at different paybacks (Payback, also called RTP (return to player): the share of all money wagered that a game pays back over the long run.), and the machines look identical. The PAR sheets showed versions of Lobstermania ranging from 85% to 96.2%.
What that does to your money
- At $1 a spin, you lose 3.8¢ a spin on average on the 96.2% version, and 15¢ on the 85% version: about four times as much.
- Start with $10 and replay your wins, and $10 lasts about 263 spins on the 96.2% game, but only about 67 on the 85% one.
What it means at sea
Cruise lines don't publish their slot holds. For comparison, Nevada's statewide slot hold was about 7.13% in 2025. You can't tell a loose machine from a tight one by looking, so the safest assumption is that ship slots hold at least as much as land casinos.
Video poker is the exception: the pay table (The list of what each winning hand pays. In Jacks or Better, 9/6 means a full house pays 9 for 1 and a flush 6 for 1; small changes move the return a lot.) on the screen tells you the return. 9/6 Jacks or Better returns 99.54%; 6/5 returns 95%.
Calculator: how long will my money last?
The average number of spins before a bankroll runs out, if you keep replaying wins. Real sessions vary a lot around this.
Volatility: why a week at sea can go either way
The payback % is a long-run average. Over a short stretch, results scatter widely around it. PAR sheets measure that scatter with the volatility index: the game's standard deviation (A measure of how far a single spin's result typically lands from the average. The bigger it is, the wilder the swings.) per spin times a z-score (How many standard deviations either side of the average you need to cover a given share of results: 1.65 (or 1.645) covers the middle 90%.) for the confidence level (1.65 for 90%). The 90% range for your actual payback is the payback % plus or minus the volatility index divided by the square root of the number of spins.
Double Diamond Deluxe (92.5% version)
Hold 7.42%, standard deviation 6.349 per spin, volatility index 10.476. The range narrows only slowly as play adds up:
| Spins | 90% range: low | 90% range: high |
|---|---|---|
| 1,000 | 59.45% | 125.71% |
| 10,000 | 82.11% | 103.06% |
| 100,000 | 89.27% | 95.90% |
| 1,000,000 | 91.54% | 93.63% |
| 10,000,000 | 92.25% | 92.92% |
From Harrigan and Dixon (2009), Table 2.
Why it matters to you
A cruise is a small sample. Two hours a day for five days at 600 spins an hour is 6,000 spins. On Double Diamond Deluxe, the 90% range for those spins runs from about 79% to 106% payback (our arithmetic). Plenty of players finish ahead, and plenty lose far more than the hold suggests.
Casinos have the opposite problem. Ashley gives the example of a 92% machine played 237,000 times in a month that held only 4%. With the maker's 90% range of 3.38% to 12.62%, that month was still within expectations.
Calculator: the range of likely results
Pick a game type or enter your own numbers. Uses the PAR-sheet formula above with a normal approximation.
| Spins | Likely payback range | Expected result |
|---|
The "high volatility" preset's standard deviation (13.6) is our back-calculation from Ashley's 237,000-spin example, not a figure she publishes. Real slot results are skewed: most sessions lose a little more than a normal curve suggests, and a few big hits pull the average up. The PAR sheet uses z = 1.65 for 90%; the calculator uses 1.645.
Virtual reels: why the jackpot is so rare
A mechanical reel with 22 stops gives 22 × 22 × 22 = 10,648 combinations on three reels. That isn't enough room for a big jackpot, so game makers map each physical stop to many "virtual" stops on a computer reel. With 72 virtual stops a reel, there are 373,248 combinations; with 256, there are 16,777,216.
Near misses by design
On Double Diamond Deluxe's first reel, the jackpot symbol has 1 virtual stop out of 72, but each blank next to it has 5. So the jackpot symbol lands just above the payline 5 times as often as on it, and just below it 5 times as often too. Researchers call this clustering, and it makes near misses far more common than chance on a plain reel would.
Video slots do it with asymmetric reels. In Lobstermania, the lobster symbols that start a bonus appear 2, 5 and 6 times on the first three reels, so players see two lobsters far more often than three.
Calculator: jackpot odds
Try 22 stops (a plain mechanical reel) against 72 or 256.
Wins that are really losses
Multi-line video slots celebrate payouts that are smaller than your bet. In the 92.5% version of Lobstermania played on all 15 lines, a spin "wins" something 33.52% of the time, but 60.73% of those wins pay back less than you bet. Bet 75¢ and win 45¢, and the machine plays its winning sounds while you lose 30¢.
Hit frequency adds up
Each line hits about 5.25% of the time. Spread across 15 lines, about a third of spins pay something, which feels like winning far more often than a single-line game.
Speed matters
Mechanical reels allow about one spin every 6 seconds (600 an hour); video slots about one every 3 seconds (1,200 an hour). Twice the speed means twice the theo per hour, and twice the comp (Short for complimentary: a reward such as a free cabin, drinks or free play that the casino gives you based on your rated play.) points.
Hand-pays feel like jackpots
At maximum bet on 15-line Lobstermania, a win big enough to be hand-paid (Paid out by casino staff instead of the machine, usually because the win is big enough to need a tax form.) by staff came every 399 spins on average. A player who starts with $100 at $3.75 a spin had an 89% chance of a hand-pay before going broke.
Harrigan and Dixon link near misses, losses disguised as wins and fast play to problem gambling risk. Knowing how they work helps you judge a session by your balance, not the lights and sounds.
Multi-game machines: your choice changes the edge
Many machines offer several games, each with its own payback. Ashley's example has three themes on one machine. A simple average of their paybacks is 92%, but what matters is what people actually play.
| Game theme | Payback | Credits played |
|---|---|---|
| Paleoman | 94% | 45,902.75 |
| Keno | 86% | 9,743 |
| Gems | 96% | 22,426 |
| Weighted by play | 93.58% | 78,071.75 |
From Ashley (2015). For you, the lesson is simple: on a multi-game machine, check the game you pick. A low-payback theme on the same cabinet costs you more per spin.
Why video poker earns comps more slowly
Ashley shows how a players club's points translate into cost. If 1 point per $1 played is worth 1¢, the casino gives back 1% of coin-in (The total amount you bet, counting every wager, including winnings you play back.). On her 78,071.75 credits that's $780.72. At a 6.42% hold, that's about 15.6% of the casino's theoretical win. Put the same play on a 2% hold game and the same $780.72 is 50% of theo. The lower the house edge, the more a fixed earn rate costs the casino.
Our analysis: points per $100 of expected loss
Applying that logic to cruise line earn rates shows why lines earn video poker more slowly than slots.
| Game and earn rate | House edge | Points per $100 of theo |
|---|---|---|
| Slots at $5 a point | 8% (assumed) | 250 |
| 8/5 Jacks or Better at $15 a point (Royal Caribbean) | 2.70% | 247 |
| 8/5 Jacks or Better at $10 a point (NCL, Virgin) | 2.70% | 370 |
| 9/6 Jacks or Better at $15 a point | 0.46% | 1,449 |
| 9/6 Jacks or Better at $10 a point | 0.46% | 2,174 |
Our arithmetic, not a cruise line figure. At $15 a point, an average video poker pay table earns about the same points per dollar of expected loss as slots do at $5, while full-pay 9/6 players still earn about six times as much. That fits Royal Caribbean slowing video poker from $10 to $15 a point in April 2026, though the line didn't give a reason.
Table games: where the edge comes from
Table games don't need PAR sheets: the edge comes straight from the rules and the payouts. Comp systems then estimate your theo from your average bet, the game's decisions per hour and the time you play.
Roulette
A single number pays 35 to 1, but a double-zero wheel has 38 pockets. Bet $1 on all 38 and you get back $36: a 2 in 38, or 5.26%, edge. A single-zero wheel has 37 pockets, so the edge drops to 1 in 37, or 2.70%.
Blackjack
With good rules and perfect strategy, the edge can be under 0.5%. Paying 6:5 instead of 3:2 on blackjacks adds about 1.39%, which multiplies that edge several times over. Comp systems typically rate blackjack at 0.75% and 70 hands an hour.
Craps and baccarat
The pass line carries a 1.41% edge, and baccarat's banker bet 1.06%. Side bets and proposition bets usually cost far more. Comp tables commonly rate craps at 48 decisions an hour and baccarat at 72.
Edges from Wizard of Odds. Try your own numbers in the theo calculator, or see how play turns into points in the rewards finder.
Play with a plan
The math always favors the house over time. Set a budget before you board, treat it as the cost of the entertainment, and stop when it's gone. If gambling stops being fun, call 1-800-GAMBLER in the US or the National Gambling Helpline on 0808 8020 133 in the UK.
Sources
The slot design figures on this page come from two published sources: Harrigan and Dixon's analysis of Ontario PAR sheets (2009) and Sheryl Ashley's casino accounting primer (2015). House edges and video poker returns come from Wizard of Odds, and Nevada's slot hold from UNLV. Anything marked as our analysis is our own arithmetic.
- Harrigan, K. A. & Dixon, M. — PAR Sheets, probabilities, and slot machine play: Implications for problem and non-problem gambling. Journal of Gambling Issues, Issue 23 (June 2009; web address as printed in the paper)
- Ashley, S. L. — Understanding Slot Machine Math Basics. Indian Gaming magazine, pp. 36–37 (December 2015)
- Wizard of Odds — House edge of casino games (updated Aug 2026)
- Wizard of Odds — Blackjack rule variations (updated Aug 2026)
- Wizard of Odds — Jacks or Better pay tables (updated Aug 2026)
- UNLV Center for Gaming Research — Nevada gaming win 2025 (2026)
- Royal Caribbean Blog — 2026 casino changes (video poker earning) (Apr 13, 2026)
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