How do slots work: what really happens on every spin?
Every spin is a separate draw, decided the moment you press the button. On Gates of Olympus, about 29 in 100 spins "win", but only about 13 actually profit; the rest pay less than the stake. 22% of everything it pays back comes through free spins, which arrive about once every 457 spins.
By the OddsLab lab · data as of 2026-10-08 04:07 UTC
- Spins that "win" on Gates of Olympus
- 29/ 100
- Spins that actually profit
- 13/ 100
- Share of the payback that comes through free spins
- 22%
But 55% of those wins are smaller than the stake.
Of every 100 spins, same game.
Free spins arrive about once every 457 spins, roughly 23 minutes of play.
What happens when you press spin?
When you press spin, the result is decided there and then by a random number generator (RNG) on the provider's server. The spinning reels on screen are only an animation showing a result that already exists. Nothing you do during the animation changes it.
Every spin stands alone. The server does not look at the previous spin, how long you have been playing, or what time it is. We tested this over millions of spins: there is no hot hour and no pattern that works.
Stakes, lines and multiples
The stake is what you bet per spin. In modern games, paylines, "ways" such as 243 or Megaways, and cluster or tumble systems only set how symbols form a win; your stake is still one number per spin.
That is why we write every win as a multiple of the stake: ×2 is twice the stake, ×100 a hundred times. Multiples let games at any stake be compared.
A "win" is not the same as a profit
Most games celebrate every win with sound and animation, including wins smaller than your stake. On Gates of Olympus, about 29 in 100 spins pay something. But 55% of those wins are smaller than the stake: you "win" and your balance still goes down. Only about 13 in 100 spins actually profit.
Of every 100 spins: how many actually profit
profitwin, but less than the stake
See the numbers behind this chart
| Game | Lab spins | Win | Win < stake | Profit per 100 spins |
|---|---|---|---|---|
| Big Bass Bonanza | 350,580 | 13.0% | 29.5% | 9.2 |
| The Dog House Megaways | 293,780 | 23.7% | 57.3% | 10.1 |
| Wild West Gold | 275,460 | 30.2% | 60.5% | 11.9 |
| Gates of Olympus 1000 | 241,980 | 28.4% | 55.1% | 12.8 |
| Gates of Olympus | 240,040 | 28.8% | 54.8% | 13.0 |
| Gates of Olympus Super Scatter | 213,620 | 28.0% | 55.9% | 12.3 |
| Starlight Princess Super Scatter | 205,960 | 27.9% | 56.2% | 12.2 |
| Starlight Princess 1000 | 204,720 | 28.3% | 55.1% | 12.7 |
Providers never publish this figure. We can count it because we record every spin, including the balance before and after.
Where does the money come back from: base game or free spins?
Most games pay back in two ways: wins in the base game, and free spins that are rare but big. How the payback splits between them decides what playing feels like.
Of every 100 staked: how much comes back through the base game and through free spins
ordinary spinsfree spins
See the numbers behind this chart
| Game | Return | From base game | From free spins | Free-spin share |
|---|---|---|---|---|
| Big Bass Bonanza | 95.8% | 40.7% | 55.1% | 58% |
| The Dog House Megaways | 97.9% | 72.6% | 25.3% | 26% |
| Wild West Gold | 96.9% | 46.0% | 50.9% | 53% |
| Gates of Olympus 1000 | 93.0% | 75.9% | 17.2% | 18% |
| Gates of Olympus | 98.9% | 77.6% | 21.3% | 22% |
| Gates of Olympus Super Scatter | 101.4% | 76.0% | 25.4% | 25% |
| Starlight Princess Super Scatter | 100.8% | 70.0% | 30.8% | 31% |
| Starlight Princess 1000 | 95.8% | 73.3% | 22.6% | 24% |
Take Gates of Olympus: ordinary spins return only about 78 of every 100 staked. The rest, 22% of all payback, waits in the free spins. So between free spins your balance almost certainly drifts down. Games with a big free-spin share feel "harsher": long quiet stretches, then one big hit.
How often do free spins come?
Free spins are the feature everyone is after, and so also the most exaggerated. Here is how often they come by our measurement, turned into ordinary playing time.
Free spins come on average once every how many spins
See the numbers behind this chart
| Game | Free spins | Minutes (3 s/spin) | Average free-spin round |
|---|---|---|---|
| Big Bass Bonanza | 1 : 112 | 6 | ×61.7 |
| Wild West Gold | 1 : 181 | 9 | ×92.2 |
| The Dog House Megaways | 1 : 379 | 19 | ×96.0 |
| Starlight Princess Super Scatter | 1 : 392 | 20 | ×120.9 |
| Starlight Princess 1000 | 1 : 429 | 21 | ×96.9 |
| Gates of Olympus | 1 : 457 | 23 | ×97.5 |
| Gates of Olympus Super Scatter | 1 : 483 | 24 | ×122.7 |
| Gates of Olympus 1000 | 1 : 494 | 25 | ×84.8 |
Free-spin frequency for every game we measure, with its margin of error, is in the Free spin ranking →
RTP and volatility: the two numbers to know
RTP is the share of stakes returned over the very long run, usually around 96%. So on average you lose about 4 of every 100 staked. RTP does not apply to one session.
Volatility is how wild a game is: frequent small wins, or long quiet stretches with the occasional big one. The "where the money comes back from" chart above is a simple way to see it. Two of our guides cover both in depth.
Should you play the demo first?
A demo is useful to learn the features and feel the volatility without money. But do not pick a real-money game from how it went in demo: in our lab, PG Soft and FA CHAI demos pay far more loosely than their official figures, which is why those games are left out of the charts on this page.
Playing with limits
- Set limits before you start. Money and time. Limits made mid-session are almost always broken.
- Treat the money you stake as the cost of entertainment. At 96% RTP, on average 4% of every stake is lost. That is the price of playing.
- Do not chase losses. We tested the "the game will pay back your losses" pattern: after 200 heavily losing spins, the next spins pay as usual. Nothing is paid back.
- Stop when you reach the limit, win or lose. There is no better hour and no spin that is "due".
- If playing starts to feel hard to stop, get help. Talk to someone you trust, or a gambling support service in your country.
How can I check this myself?
- Every game we measure has a page with the figures above, updated hourly. All games →
- Download the raw record of every spin and count for yourself how many profit and how much comes from free spins. Verify the data →
- Read how we record and reconcile the balance on every spin. Full methodology →
Frequently asked questions
How do online slot machines work?
Each spin is decided by a random number generator on the server when you press the button. The reels on screen are only animation. Every spin stands alone.
Why do I win often but my balance goes down?
Because many wins are smaller than the stake. On Gates of Olympus about 29 in 100 spins pay, but only about 13 actually profit.
How often do free spins come?
It depends on the game. On Gates of Olympus about once every 457 spins by our measurement. In some other games far more often, but for smaller prizes.
Is there a way to win at slots?
Not over the long run. An RTP below 100% means you lose part of every stake on average. Patterns and hot hours did not hold up in our data.
Do bigger stakes win more often?
No. Wins are counted as multiples of the stake; the odds are the same, only the amounts are bigger, including the losses.
Should I play the demo first?
It helps to learn the features. But some providers' demos are far looser than the real-money version, so winning in demo is no guide.
How do I play safely?
Set money and time limits before you start, do not chase losses, and stop when you reach the limit.
The data behind this guide
18+ only. OddsLab is a measurement site: we take no bets, have no casino partners and link to no casino. There is no way to beat a slot machine over the long run.