Progressive jackpots: who funds them & what the odds really are

How a progressive jackpot grows from players’ stakes, how linked networks work, what the odds & return to player look like, & what Britain’s rules require.

What a progressive jackpot is

A progressive jackpot is a top prize that, in the words of Wikipedia’s entry on the subject, “increases each time the game is played” but is not won. Once someone wins it, “the jackpot for the next play is reset to a predetermined value” & starts growing again under the same rule.

That reset amount is often called the seed. In an analysis of Megabucks, a linked slot game in Nevada, that draws on figures up to 2010, the site Wizard of Odds says that according to a source it describes as defunct, “starting in September 2005, Megabucks was reset to a jackpot of $10 million”, & that before then the reset value was $7 million. PlaySmart gives a different figure, saying the minimum jackpot for MegaBucks starts at $1 million.

Wikipedia says progressive jackpots were first introduced in large casinos in 1986, & that the first progressive slot machine was Megabucks, developed by International Game Technology (IGT). It records that a player won the first progressive jackpot, $4,988,842.17, on 1 February 1987.

How every stake feeds the jackpot

According to PlaySmart, “a percentage of each coin or credit played is added back into the jackpot”, so the prize is fuelled by the bets themselves. Wikipedia adds that the jackpot rises by a small predetermined amount on each play, & that the size of that increment is set by the casino.

The money comes out of the house edge, the share of stakes an operator expects to keep over time. Wikipedia gives an example: “on a machine whose house edge is 5%, a generous jackpot contribution might be 1%”, which it describes as one fifth of the expected profit.

Wikipedia says operators accept this cost because a progressive draws players through its novelty, its constantly changing meter & the sheer size of the prize. Writing about Megabucks, Casino.org says “a small portion of the bet gets placed into a jackpot” & that IGT, not the casinos, pays out the jackpots.

In Britain, the Gambling Commission’s remote gambling technical standard RTS 9, made under the Gambling Act 2005 & last updated on 23 November 2023, says “An explanation of the jackpot rules must be clearly available to the customer before they commit to gamble.”

Its guidance says those rules “shall describe how it is funded, what the start-up seed and any ceiling values are”. Where a jackpot is capped at a ceiling, the rules should explain what happens to later contributions, for example any overflow or reserve pools.

Standalone, linked & wide-area progressives

Pennsylvania’s gaming regulations, 58 Pa. Code § 461a.12, state that “A progressive slot machine may stand alone or be linked with other progressive slot machines.” Under that code, linked machines must have the same chance of hitting the jackpot combination & each must increment the shared meter “by the same rate of progression”.

The same code lets linked machines use different denominations or required wagers, provided the chance of winning is directly proportional to the wager needed & a notice of that proportional chance is displayed on each machine.

PlaySmart describes networks linking the machines “in a casino, or even a whole city”, all feeding the same jackpot. It adds that a game like OLG’s POWERBUCKS can link casino games on mobile phones, tablets & desktop computers to grow one prize.

Wikipedia notes that pooled machines form a jackpot that “grows more quickly” because more losing plays count towards it. The Pennsylvania code refers to “a wide area progressive system offered at multiple licensed facilities”, & Casino.org says Megabucks jackpots can be won at any of Nevada’s approximately 750 Megabucks machines.

Large networks can stack several prizes. Wikipedia describes a scheme with “one main jackpot, several intermediate jackpots paid at the regional level, smaller jackpots paid at the site level” & the smallest tied to individual machines.

The odds: a bigger jackpot is not more likely

Wizard of Odds, citing John Robison & a Las Vegas Sun article of 24 December 1999, gives the probability of hitting the Megabucks jackpot as 1 in 49,836,032. Its calculations assume each player bets “the $3 required to win the jackpot”.

Pennsylvania requires the calculated probability of winning each progressive jackpot to be submitted for approval, & says “The probability may not exceed 50 million to 1.” Once an amount appears on a meter, the code says the probability of hitting the jackpot combination may not be decreased unless the jackpot has been won, transferred or removed under set conditions.

A growing meter does not change the chance on each play. PlaySmart says “your odds of winning any given prize stay the same, even as the jackpot grows”, & calls the idea that a big jackpot is due “really just wishful thinking”.

A must-hit-by jackpot works differently. Wikipedia says its value “is determined immediately after the preceding jackpot is won” by a random number generator (software that produces unpredictable outcomes), within a publicly disclosed range such as $1,000 to $3,000, & it pays on the wager that pushes the jackpot to that hidden threshold.

Wikipedia adds that these “mystery jackpots” do not depend on any result in the main game, & that the chance of winning on a given spin is usually in proportion to the amount bet.

The RTP trade-off

Return to player (RTP) is the share of all money staked that a game pays back over the long run. Using Nevada Gaming Control Board figures for 1994 to 2009, Wizard of Odds puts Megabucks’ overall return at 88.61%, of which 10.18% came back as jackpots & “88.61% – 10.18% = 78.44%” as ordinary wins.

It estimates the return at any moment as “78.44% + 0.6689%×m, where m is the number in millions of the current jackpot”. At a $15 million jackpot, it calculates a return of 88.47%.

The same analysis puts the average point at which the jackpot hits at $15,215,248, & the point at which the game returns 100% at $32,238,319. It estimates the chance of any given jackpot growing that big at 1.41%, & stresses that all its figures are ballpark estimates.

Megabucks jackpots are paid as a 25-year annuity, according to Wizard of Odds. Under the interest rate it assumed, it values that annuity at 61.07% of face value.

Eligibility & UK jackpot rules

Wikipedia says “Usually the progressive jackpot is only offered to players who wager the maximum number of credits per play”, yet “All wagers, whether or not they are maximum-credit bets, contribute to the jackpot.”

RTS 9 takes a different approach for remote gambling in Britain. Its guidance says a customer who contributes to a jackpot pool “should be eligible to win the jackpot whilst they are playing that game”, & that “The chances of winning a jackpot should increase in correlation with the amount contributed.”

If a player is not eligible for a game’s progressive prize, RTS 9 says this should be made clear, along with their theoretical RTP. It also says “All eligible players should be able to see the current jackpot values”, updated as often as practicable, particularly after a reset.

The standard requires the rules to explain what happens when two or more players trigger the same jackpot at once. If a jackpot holding player money is decommissioned, contributions must be returned fairly, “with priority given to the players who made the contributions”.

Record wins

Casino.org reports that “The top seven slot jackpots in Las Vegas history were all hit on Megabucks progressive machines.” The largest, $39.7 million, was won at the Excalibur on 21 March 2003 by an anonymous 25-year-old software engineer from Los Angeles.

Casino.org describes that win as the largest jackpot ever, “in Vegas or anywhere else”. Second on its list is $34.9 million at the Desert Inn on 26 January 2000, & the most recent entry is $17.3 million at the M Resort on 14 December 2012.

Jackpot pressure, limits & help

PlaySmart says that when a progressive goes unwon, the larger prize “creates a lot of pressure to play”. Its guidance is not to feel pressured into a bet because of the prize, & to “set a personal limit and play within it”.

The Gambling Commission’s self-exclusion page describes self-exclusion as “a tool used by those who have recognised that their gambling is harmful to them”. It says “GAMSTOP ONLINE allows you to self-exclude from online operators with one request”.

The Commission adds that multi-operator schemes let people self-exclude from the same type of land-based gambling in their area, & that GamCare’s website has information on software that blocks gambling sites. Once an agreement is made, it says the business must close the account & return any money in it.

Questions

Does a bigger progressive jackpot mean I am more likely to win it?

No. PlaySmart says the odds of winning any given prize “stay the same, even as the jackpot grows”, & calls the idea of a jackpot being due “wishful thinking”.

What are the odds of winning Megabucks?

Wizard of Odds, citing John Robison, gives the probability of hitting the Megabucks jackpot as 1 in 49,836,032, on the $3 bet required to win it.

Who pays for a progressive jackpot?

Players do, through a slice of each stake. PlaySmart says a percentage of each coin or credit played is added to the jackpot, & Casino.org says IGT, not the casinos, pays out Megabucks jackpots.

What is a must-hit-by jackpot?

According to Wikipedia, its trigger value is set by a random number generator immediately after the previous jackpot is won, within a publicly disclosed range, & it pays on the wager that takes the jackpot to that value.

What must an online jackpot’s rules show in Britain?

Under the Gambling Commission’s RTS 9, the rules must be clearly available before a customer commits to gamble & must describe how the jackpot is funded, its start-up seed & any ceiling values.

Sources

• gamblingcommission.gov.uk
• law.cornell.edu
• en.wikipedia.org
• playsmart.ca
• wizardofodds.com
• casino.org
• gamblingcommission.gov.uk

Sources checked 30 October 2026. Information only. 18+.