A slot lobby usually shows two kinds of top prize. One is a fixed multiple of your stake, printed in the paytable and the same for everyone. The other is a running total that climbs while you watch it, sometimes into seven figures. The second is a progressive jackpot, and it is funded in a way that changes the economics of the game underneath it.

This guide explains how each type is funded, what a progressive costs you in the base game, the eligibility rules that catch people out, and how to decide which suits the way you play. Our guides to slot RTP and volatility cover the two numbers behind all of this.

How a fixed jackpot works

A fixed jackpot is simply the top line of the paytable. It pays a set multiple of your stake, it is included in the game’s published RTP, and it does not change no matter how many people play or how long it has been since it last landed.

Because it is part of the ordinary paytable, everything you already know about the game applies to it. The stated RTP accounts for it, and the volatility of the game reflects how rarely it lands. There is no separate pool and no separate rules.

How a progressive is funded

A progressive works differently. A small percentage of every qualifying stake is diverted into a shared pool, which grows until somebody wins it and then resets to a seed amount funded by the operator or the provider.

The consequence that matters is that the money in that pool came out of the same pot that would otherwise have paid ordinary wins. The game’s total return can still be 96%, but a portion of that 96% is locked inside a prize that almost nobody will ever receive.

What the jackpot contribution costs you

Providers often split the figure into two parts: the return you get from normal play, and the return attributable to the jackpot.

That last row is the honest summary. If you play a progressive and do not win the jackpot, which is overwhelmingly the likely outcome, you are playing a game with a lower effective return than its headline RTP implies. You are paying a small premium on every spin for a lottery ticket attached to the game.

This is not hidden or improper; it is how the product is built. It is simply worth knowing that two 96% games in the same lobby are not equivalent for a player who is not going to win the jackpot.

Standalone, local and networked

• Standalone. The pool builds from a single game at a single operator. Smallest totals, and the best chance relative to the size of the prize.
• Local. Shared across several games at the same operator. Middling on both counts.
• Networked. Shared across every operator running the game, often across many countries. These are the totals that reach the headlines, and the longest odds by a wide margin.

The size of the prize and the chance of winning it move in opposite directions, which is worth remembering when a very large number is the thing that drew you to the game.

Eligibility rules that catch people out

Progressives carry conditions that fixed jackpots do not, and each one has produced a familiar complaint:

• Minimum qualifying stake. Many progressives only qualify at or above a set bet size, or scale eligibility with the stake. Playing below it can mean the jackpot cannot be won at all.
• Maximum bet while a bonus is active. If a bonus is running, the maximum bet rule may sit below the qualifying stake, which quietly makes the jackpot unreachable during wagering.
• Bonus play exclusion. Some operators exclude jackpot wins made with bonus funds, or cap what can be converted.
• Payment in instalments. Very large wins are sometimes paid over months under a separate clause in the withdrawal terms.

All four live in the terms rather than in the game. Our guide to reading casino terms covers where those clauses sit, and the wagering requirements guide explains the maximum bet rule.

The odds, and why they are rarely published

Providers publish RTP, and most publish volatility. Very few publish the probability of hitting a networked jackpot, and where a figure does appear it is usually expressed as odds per spin at the qualifying stake, on a scale most people find hard to hold in mind.

A reasonable way to think about it: the prize is large precisely because the chance is small, and the two are locked together by the arithmetic. A pool that reaches seven figures got there by collecting small slices from an enormous number of losing spins. There is no version of the product where the prize is large and the chance is meaningful.

Which one suits you

If what you want is a long session on a modest budget, a fixed jackpot game with low volatility is the better fit, and the return you experience will sit closer to the return that is advertised.

If what you want is the chance, however remote, at a life changing number, a progressive is the only product that offers it, and the right way to buy it is knowingly: at the minimum qualifying stake, with a session budget you have already decided to spend, and with no expectation that the base game will carry you. Treat the difference between the two as the price of the ticket rather than as bad luck.