Progressive jackpot (definition and maths)
A progressive jackpot is a prize pool that grows with every play until someone wins it. How the pool grows and how fixed jackpots like Sun Temple's differ.
On this page
A progressive jackpot is a prize that grows each time the game is played. A small slice of every stake is added to a pool; when someone wins the jackpot, the pool resets to a starting amount and begins growing again. Because the prize keeps rising, it can reach far more than any fixed top prize.
How the pool grows
Suppose a progressive game adds 1 percent of every bet to the jackpot. A 100-coin spin adds 1 coin, and a 1,000-coin spin adds 10. If players make a million 100-coin spins between wins, the pool grows by 1,000,000 coins on top of its starting amount. The pool can be shared across many machines or players, which is how it grows quickly, or it can belong to a single game.
The contribution comes out of the game's return. A slot that returns 97 percent with a 1 percent jackpot contribution pays the other 96 percent through ordinary prizes, so the base game is a little tighter. Over a very long run, the jackpot's expected share of the return is the same as the contribution, since on average the pool paid out equals the pool paid in.
Fixed jackpots versus progressive ones
Not every "jackpot" is progressive. Cashout Arcade's Sun Temple awards jackpots inside its Temple Link bonus as fixed multiples of your bet, drawn from a table, not from a pool:
| Scarab | Prize (times your bet) | Chance per spin |
|---|---|---|
| Mini | 20.4747x | 1 in 465 |
| Major | 102.3738x | 1 in 1,200 |
| Grand | 1023.7388x | 1 in 5,784 |
These prizes do not grow with other players' spins, and nothing is saved up for the next winner. The size is known in advance, and the odds page shows exactly how likely each is.
Why the difference matters
A progressive jackpot's value changes over time, so the same game can be a slightly better or worse deal depending on how high the pool has grown. A fixed jackpot always has the same expected value. Neither can change the fact that the chance of hitting the top prize on any one spin is very small.
Common misconceptions
- "A big pool means the jackpot is due." The chance per spin does not rise with the pool. See Gambler's fallacy (definition and example).
- "Betting more makes me more likely to win it." On some games it only unlocks eligibility. Chance stays proportional to the stake.
- "Jackpots are cash." Coins in Cashout Arcade are virtual and have no cash value.
For the other terms in a slot's bonus, see Casino Game Terms: Slots, Tables and Arcade Games Defined, and for chances see the Odds page.