Popular slot types
How online slots work
Every online slot is driven by a random number generator (RNG) that picks a result the instant you press spin. The reels are just animation. Each spin is independent: the game has no memory of the last result, and no slot is ever "due" to pay.
What makes slots different from each other is their maths model, summed up in three numbers you'll find in the game's information panel:
| Number | What it tells you | Where to learn more |
|---|---|---|
| RTP | The share of all bets paid back over millions of spins — the long-run cost | What is RTP? |
| Volatility | Whether wins are small and frequent or rare and large | Slot volatility explained |
| Max win | The biggest possible multiplier of your stake | A big max win usually means high volatility |
Two slots with the same RTP can feel completely different. Choose RTP for value and volatility for experience.
Where to play online slots
In the US, real-money online slots are legal only in states that license online casinos. In New Jersey, Pennsylvania, Michigan and West Virginia, BetMGM has one of the largest slot lobbies, with exclusive titles and networked jackpots, and DraftKings Casino mixes major studios with in-house games. bet365 offers a smaller, tidy lobby in New Jersey and Pennsylvania.
Internationally — Canada, New Zealand, Ireland and beyond — Jackpot City has 1,000+ games including the Mega Moolah network, and Spin Casino offers the best app in the same family. See our full best online casinos ranking.
Types of online slots
| Type | How it works | Typical volatility |
|---|---|---|
| Classic (3-reel) | Few paylines, simple symbols, small bonus features | Low to medium |
| Video slots | 5+ reels, 10–50 paylines or 243+ ways, free spins and bonus rounds | Any |
| Megaways | Reel heights change every spin, up to 117,649 ways or more — see Megaways explained | High |
| Cluster pays | Wins form from groups of matching symbols anywhere on the grid | Medium to high |
| Hold-and-win | Collect cash symbols that lock in place for respins | Medium to high |
| Progressive jackpots | Part of each bet feeds a growing prize — see jackpot casinos | High; lower base RTP |
Slot features in plain English
- Wild — substitutes for other symbols to complete a win.
- Scatter — pays anywhere on the reels and usually triggers free spins.
- Free spins — bonus rounds played at no cost, often with multipliers.
- Multiplier — multiplies a win (x2, x5, x100…).
- Cascades / tumbles — winning symbols disappear and new ones fall in for another chance.
- Bonus buy — pay a fixed price (often 100x the stake) to go straight to the feature; banned in some markets, including Great Britain.
Well-known slots and their RTPs
| Slot | Studio | Published RTP (max version) | Volatility |
|---|---|---|---|
| Starburst | NetEnt | 96.09% | Low |
| Gonzo's Quest | NetEnt | 95.97% | Medium |
| Big Bass Bonanza | Pragmatic Play | 96.71% | High |
| Gates of Olympus | Pragmatic Play | 96.50% | High |
| Book of Dead | Play'n GO | 96.21% | High |
| Mega Moolah | Games Global | ~88% (including the jackpot contribution) | High |
Many slots ship in several RTP versions and each casino chooses one, so check the game's information screen. For the highest-RTP picks, see highest RTP slots.
Choosing a slot
- Check the RTP at your casino (the same slot can run at 96% in one casino and 94% in another).
- Pick a volatility that matches your budget and patience.
- Try the demo — most licensed casinos let you play slots for free first.
- Set your stake: on a high-volatility slot, about 1% of your session budget per spin is a sensible ceiling.
Our slot budget calculator shows how much a session costs on average at any stake and RTP.
Slots and bonuses
Slots usually count 100% towards bonus wagering, which makes them the natural choice for clearing a welcome offer. Watch for exceptions: some studios' slots count 50% (NetEnt at the Super Group casinos), re-spin slots can count 10%, and progressive jackpots often count 0%. Read wagering requirements explained, and value spin offers with our free spins calculator.
What we look for at a slot site
- Clear RTP and volatility information for every game.
- Independent game testing by labs such as eCOGRA, GLI or iTech Labs.
- Big studio range — Games Global, Pragmatic Play, IGT, Light & Wonder, NetEnt, Play'n GO and others.
- Demo play so you can try before you stake.
- Fair bonus terms with slots counting 100% and wagering under 40x.
- Fast payouts once you win — see our guide to casino withdrawal times.
Curious about the history? Read a short history of the slot machine or learn how Megaways changed modern slots.
