Class II vs. Class III Slot Machines: What's the Difference?

Play enough in Oklahoma and you’ll eventually notice a tiny bingo card in the corner of a slot screen. That isn’t decoration. On a lot of machines, the bingo game is the game, and the spinning reels are just a way of showing you how it turned out. That’s a Class II machine, and it works differently from the Class III slots you’d find in Vegas or at Coushatta.

The short version

A Class III machine decides your spin with its own random number generator, like a traditional slot. A Class II machine decides it with an electronic bingo game played against other players on a network, then shows the result as spinning reels. They look almost identical from the chair. Both are random, and neither one is a trick.

Where the classes come from

The names come from the Indian Gaming Regulatory Act, a federal law passed in 1988 that sorts tribal gaming into three classes:

Class I is traditional tribal games and social games played for small prizes. You won’t run into these on a casino floor.
Class II is bingo and games like it, such as pull-tabs, including electronic versions. Tribes regulate these themselves, with oversight from the National Indian Gaming Commission. They don’t need an agreement with the state.
Class III is everything else, which is what most people picture as a casino: traditional slot machines, blackjack, roulette, craps. A tribe can only offer Class III games under a compact (a formal agreement) with the state.

That last point is the whole reason Class II machines exist. A bingo-based machine gives a tribe slot-style games under federal rules, whatever its state agreement covers.

How a Class III slot decides your spin

This is the classic slot machine. When you press spin, the machine’s own random number generator picks a number, and that number maps to an outcome. The machine doesn’t need anybody else. Your spin is between you and that one cabinet.

How a Class II machine decides your spin

On a Class II machine, pressing spin enters you into a bingo game:

Your machine gives you a bingo card (that little grid on screen).
A computer draws the numbers for that game, which can include other players’ machines on the same network.
Your card is checked against the winning patterns. The pattern you hit, if any, decides what you win.
The reels spin and stop on a result that matches the prize the bingo game already decided.

It all happens in about the same time as a regular spin, so most people never notice. Because it’s bingo, you’re playing against other people’s cards and not only the machine, which is why these games are linked together on a network.

How to tell which one you’re playing

From the outside they look the same: same cabinets, same game themes, same bonus rounds. A few tells:

The bingo card. Most Class II games show a small bingo card somewhere on the screen, often in a corner.
The help screens. Tap the “i” or help button. Class II games usually mention bingo in the rules.
Ask. A slot attendant can tell you which machines on the floor are which.

Does one pay better than the other?

You can’t tell by looking. Both kinds are built by game makers with a set math model (we cover how that works in Do Slot Machines Really Just Run on Math?), and both have a long-run payback that you won’t see posted on the machine. Most tribal casinos don’t publish game-by-game payback numbers either way.

What we can say is that the bingo isn’t a trick. It’s the legal mechanism that decides the outcome, the draw is random, and the result you see on the reels is the result you got.

Where you’ll run into them

Oklahoma has one of the biggest Class II markets in the country, so if you play there you’ve almost certainly played bingo-based machines without knowing it. You’ll also see games allowed under Oklahoma’s compacts with the tribes, often on the same floor.

Louisiana’s tribal casinos, including Coushatta, operate under gaming compacts with the state.

So does it matter at the casino?

For your night out, not much. Class II or Class III, every spin is random, nothing you do changes the odds, and the same rules apply: set your budget before you sit down and play the games you enjoy. But next time you spot that little bingo card in the corner, you’ll know what it’s doing there.