The figure everybody quotes and nobody sources

A "progressive" jackpot is not a sum the house has set aside for a lucky customer. It is a running total of small deductions taken from the stakes of everyone who played before, and it sits in a "pool" until one spin empties it. That pool is shared by every casino carrying the game, and the games which feed it are its "network".

That makes the size of the deduction (the "contribution", in the trade's own word) the only honest place to begin, and it is the one number the pages describing these games almost never print. What they print instead is a phrase, "around one or two per cent", handed from one comparison site to the next with no source attached to it, and we have now read enough of those pages to say that the phrase measures nothing whatever.

Set against that phrase there are three things which can actually be read. The first two are the suppliers' own game rules and the figures that licensed operators are obliged to state correctly inside their own markets.

The third is the published "return to player" (the share of stakes a game gives back over time). That third one helps only on the rare title issued in two versions, one with a jackpot bolted on and one without, and such titles are vanishingly few.

Together they give a range which opens at 0.99 per cent and closes at 7.60 (Age of the Gods at one end of it, Mega Fortune at the other), a factor of nearly eight between the thriftiest network and the dearest, so in our view the familiar phrase is not merely vague but wrong for most of the networks you are likely to open.

What each network takes out of a stake

The number that survived arithmetic, and the ones that cannot be checked

The most useful figure in that table is one nobody published. Games Global has never stated what Mega Moolah takes, and the 5.30 per cent reaches us through an affiliate page (read on 18 October 2026); what makes the number usable anyway is that it survives a check. On every one of the twenty-nine titles in that network, the "base return" (what the slot pays before the pot is counted) plus 5.30 lands exactly on the total the supplier does publish.

The Playtech end of the table has no such confirmation. The 0.99 per cent credited to Age of the Gods rests on a single secondary source (a game database rather than Playtech), and we print it because the alternative is to leave the cheapest network in this trade with no number beside its name, which would be the more misleading of the two choices.

Two of the entries are not shares of a stake in any sense, and lining them up with the others would be a category error rather than a rounding. Red Tiger holds back 3 per cent of "aggregated funds" (the pooled takings of the whole network, and not the individual bet), a quantity nobody has shown how to convert into a per-spin figure.

The Caribbean Stud line, at 65 to 71 per cent, is the share of a "side bet" (a separate and optional wager placed beside the main hand) in "land-based" rooms, and the deduction there is colossal precisely because nothing obliges anybody to make that wager. Both figures are real, and neither belongs in a ranking with the slot networks.

The fifth of the contribution that never reaches the counter

The most instructive sentence in the whole of this subject sits in the game rules of Divine Fortune Gold (a NetEnt title, and not the better known Divine Fortune), and we have found it quoted almost nowhere! Of the 3.70 per cent that the game sends towards its "Mega Jackpot", a fifth is held back (the proportion is stated in the rules themselves): it never appears on the "counter" (the climbing figure on the screen), and is reserved instead to "reseed" the following jackpot once this one has been collected.

Two consequences follow, and both of them are usually told the wrong way round. The first is arithmetical, and it is the smaller of the two: the counter climbs more slowly than the stated "contribution" implies, so a reader who multiplies the percentage by the turnover of a network will always overestimate the speed at which the pot is filling.

The second consequence changes how the whole product looks, and it is the reason we gave the subject a page. The "seed" (the figure a level restarts at once somebody has collected it) is neither a gift from the supplier nor a subsidy from the casino: it is money already taken from the players who lost in the previous cycle, parked for a round that has not begun.

The general case is put plainly enough in the reference literature, which notes that the house may provide "no real seed money" at all and has to fund the minimum of each jackpot out of the margin of the main game.

That single observation is worth more than the entire promotional vocabulary built on top of it, because it explains why a large opening figure is a selling point and not a generosity, and why the word "guaranteed", which appears on so many of these counters, describes a schedule rather than a gift.

What the published returns can be made to admit

Where a supplier says nothing at all, one method still works, and you can run it without the cooperation of anybody: find a game issued in two versions and subtract the one from the other.

Money Train Origins is the clean case (one game, two published returns, one supplier), and the cleanest instance we found anywhere in this trade. The ordinary version is published at a return of 96.11 per cent, and the Dream Drop version of the identical game at 94.00, so the jackpot costs 2.11 points of return; that figure is not an estimate but the gap between two numbers the supplier prints itself.

Mega Fortune permits the same operation from the inside, because NetEnt publishes a total of 96.60 per cent together with a "breakdown" in which 7.60 points are assigned to the progressives (62.8 go to the base game, 16.8 to the free spins and 9.3 to the bonus round), and the two readings corroborate one another.

That breakdown, however, reaches us from a secondary source rather than from NetEnt, so we mark it as such, while the total stands on the supplier's own page. What a reader then does with the subtraction belongs to a page of its own, on how the return of a jackpot slot splits in two, because what matters in the end is not what the pot takes but what is left for everybody who fails to win it.

The networks that publish nothing at all

Five of the networks you are most likely to meet publish no contribution figure whatever, so that the entry against each of them in our table reads "not published", and three of them are among the largest launches of the past decade: Jackpot King (2017), WowPot!, Dream Drop (May 2022), Jackpot Play and Jackpot Madness (August 2026).

That silence is not an oversight on our part, and it is not a secret kept from any regulator either, because nothing in a licence obliges a supplier to publish the split; it simply means that on those five networks nobody outside the company can say what a stake is buying.

Jackpot Madness goes one step further, and the step is written into the launch announcement rather than deduced by us: contributions, margins and payout levels are "configurable by the operator", and the network can be run ring-fenced inside a single brand (which makes the comparison harder still); the phrase is the supplier's own and not a gloss of ours, and it means that the same game on the same network can be a different proposition at two casinos which both carry it.

A reader who wants the contribution of a network that keeps it private has, so far as we can see, exactly one lever, and it is the published return of the game in front of him, read against a "plain" title of the same generation with no pot attached (96 per cent is the ordinary figure for one). It is a poor lever. It is also the only one anybody has!

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