History of slot machines

History of slot machines begins with 1890s poker drums

Before reels and fruit, there were playing cards. The earliest machine usually named in slot histories is a poker game built by Sittman and Pitt of Brooklyn, New York, which Wikipedia's slot machine history article (opens in a new tab) dates to an 1893 design. The player put in a nickel and pulled a lever to spin five drums carrying 50 card faces between them, hoping to land a strong poker hand.

The machine paid nothing itself. A good hand was rewarded by the bar or shop that owned it, with prizes such as a free beer or a cigar, so the 'payout' depended entirely on the owner. That is the first lesson in the history of slot machines: the house set the prize, not the player.

The first built-in house edge

Owners improved their odds by removing two cards, the ten of spades and the jack of hearts, from the drums. Taking out those two cards halved the number of ways to make a royal flush, which doubled the odds against the best hand. No strategy could get round that: it was a change to the maths of the machine, just as a modern slot's paytable sets its return to player before anyone spins.

Charles Fey and the Liberty Bell slot machine

The design that shaped every later slot came from Charles Fey, born August Fey in Bavaria in 1862, who settled in San Francisco and started work there in 1885. In 1895 he built a modified Horseshoe machine that paid out coins, after Schultze's 1893 Horseshoe machine had become the first to pay automatically.

Fey's Liberty Bell had three reels and five symbols: horseshoes, diamonds, spades, hearts and a Liberty Bell, which gave the machine its name. Three bells paid the top prize of ten nickels, or 50 cents. Sources disagree on the date. One account places it somewhere between 1887 and 1895, another gives 1898, and an 1899 example survives in the Nevada State Museum's Fey Collection, so 'by 1899' is the safe way to put it.

Gambling was illegal in California, so Fey could not patent the Liberty Bell, and copies spread quickly. His own machine was banned in California after a few years, but demand elsewhere stayed high. The basic shape he settled on, three reels, a handful of symbols and a fixed payout for a winning line, is still what people picture when they think of classic 3-reel slots.

The table is arithmetic for illustration, not the reel strips of any real machine. It shows why the number of stops matters more than the look of the reels.

Why slot machines have fruit symbols and the bar

Chicago's Mills Novelty Company brought the Liberty Bell to a mass market. Herbert Mills produced a Liberty Bell in 1907; one source calls it a copy of Fey's machine and another says Mills worked with Fey. Mills had already made the Owl in 1897, described as the first mechanical upright cabinet slot.

The Mills Operator Bell could carry a gum-vending attachment. Because the gum was fruit-flavoured, the reels gained lemons, cherries, oranges and plums, and a stick of Bell-Fruit Gum pictured on the machine became the bar symbol. Other makers, including Caille, Watling, Jennings and Pace, took up the same symbol set, which is why fruit slots still use it today.

Vending was also a legal disguise. Some operators gave food prizes to keep clear of gambling laws, but courts did not always accept it: Iowa judges treated vending machines as gambling devices in State v. Ellis (1925) and State v. Striggles (1926).

Bans, Nevada and the spread of the slot

Slots grew up under constant legal pressure in the United States. Nevada outlawed gambling in 1909 as part of a nationwide anti-gambling drive, then legalised it again on 19 March 1931. By 1908 Bell machines were already installed in cigar stores, barber shops and brothels, according to histories of the trade.

Most US states still restrict private ownership of slot machines, often allowing antiques above a certain age, though the details vary by state. For British readers, the more important story is what happened when the machines crossed the Atlantic and met UK law, covered below.

From levers to motors: electromechanical slots

Bally's 1940 High Hand, a draw-poker machine, showed early electromechanical construction. The big step was Bally's Money Honey, dated 1963 by some sources and 1964 by others, which is described as the first fully electromechanical slot. It had a hopper that could pay up to 500 coins automatically, so wins no longer depended on an attendant.

Money Honey still had a cranked lever and was played standing up, but the motorised hopper made bigger prizes practical. Larger, faster payouts made slots more attractive to casinos, and the lever became decoration rather than mechanism.

Video slots, virtual reels and random number generators

Fortune Coin Co. built the first video slot in 1976, using a modified 19-inch Sony Trinitron screen. Production units were tried at the Las Vegas Hilton before Nevada approved them, and in 1978 the company and its technology were bought by Sircoma, the business that became IGT in 1981. Today IGT slots are still a large part of the land and online market.

The quiet revolution came in 1984, when the Norwegian mathematician Inge Telnaes received US patent 4,448,419 for using a random number generator to pick reel stops. A machine could now map each reel to, say, 256 virtual stops, giving 256 × 256 × 256 = 16,777,216 combinations, even though the physical reel showed only a couple of dozen symbols. That is why a jackpot symbol can appear often on the reels yet line up very rarely. Modern random number generators work on the same principle.

Bonus screens and progressive jackpots

Second-screen bonus rounds arrived in the 1990s: Three Bags Full in Australia in 1994, then WMS's Reel 'Em In in the US in 1996. Wide-area progressive jackpots arrived around 1986 with IGT's Megabucks, whose first jackpot, $4,988,842.17, was won on 1 February 1987. Both ideas live on in today's bonus rounds and progressive jackpot slots.

UK fruit machines: holds, nudges and the Gaming Act 1968

Britain wrote its own chapter in the history of slot machines. In UK law the pub machine became the Category C gaming machine, often called a fruit machine, one-armed bandit or AWP (amusement with prizes). British machines added features rarely seen elsewhere: the hold, which keeps one or more reels for the next spin, and the fruit machine nudge, which turns a chosen reel one step. Many use a compensated model, where results may be influenced by previous play rather than drawn purely at random.

The Gaming Act 1968 gave machines their own part of the law, Part III, which you can read in the Gaming Act 1968 on legislation.gov.uk (opens in a new tab). It separated jackpot machines in casinos, bingo halls and members' clubs from AWPs in pubs and arcades. By a 2001 review, jackpot machines took up to 50p a play, with top prizes of £1,000 in casinos, while AWPs took 30p with a £5 cash or £8 token prize. An order from 27 October 2006 raised the AWP stake to 50p and the all-cash prize from £25 to £35.

The machines were everywhere. Electrocoin's Bar-X, created in 1981, had sold more than 20,000 units by early 1993, and in 2005 Great Britain had about 235,000 gaming machines, 192,000 of them AWPs. Under the Gambling Act 2005, machines moved into categories A to D, which still set stake and prize caps today.

The difference between slots and fruit machines is therefore partly legal: online slots have no statutory prize cap, while every land-based machine sits in a category with fixed limits. See our page on land-based casino rules for where each category may be sited.

The online slot era: from Thunderstruck to Megaways

The most recent chapter in the history of slot machines is online. Online casinos appeared in the mid-1990s, and slots soon became their biggest product; our history of online casinos covers that story. Some early titles are still offered: Thunderstruck, originally from Microgaming and now with Games Global, dates from 2004, and the Mega Moolah progressive from November 2006.

The biggest design shift of the last decade was Big Time Gaming's Megaways mechanic, a random reel modifier that changes the number of symbols on each reel every spin. It debuted in Dragon Born around 2015–16, and Bonanza Megaways followed in December 2016 with up to 117,649 ways. BTG then licensed the mechanic to other studios, starting with Blueprint Gaming in May 2018. Read more on the Megaways mechanic and the Big Time Gaming studio.

How UK rules reshaped online slots after 2020

Britain now has some of the tightest online slot rules anywhere. Since 31 October 2021, UK online slots have had no autoplay, a minimum of 2.5 seconds per spin, no turbo or slam-stop, and no celebrating a return that is lower than the stake. From 17 January 2025 the autoplay ban was extended to all online casino games, and other casino games must allow at least 5 seconds per game cycle. See our page on UK game design rules for the full list.

Stake limits followed: £5 a spin for players aged 25 and over from 9 April 2025, and £2 for 18–24s from 21 May 2025, set out in the Gambling Commission's online slots stake limit guidance (opens in a new tab). Since a Gambling Commission warning in January 2020, feature buy-ins are not offered to British players; our bonus buy page explains what that means. Gamble features are a separate thing and are not banned.

History of slot machines: a dated timeline

What the history of slot machines means for the cost of a spin

The machines changed beyond recognition, but the business model did not. Every slot, from the poker drums with two cards missing to a Megaways game, pays back less than it takes over time. The modern measure is RTP, and the house edge is simply 100% minus RTP. Here is what that means for £20 staked as 200 spins at 10p on three slots with published figures.

These are long-run averages. In any one session the result can be far better or worse, and how far it swings depends on volatility. Rainbow Riches comes from Barcrest, a name long linked with British fruit machines, which shows how directly the pub tradition fed into online play. The classic-style Mega Joker advertises up to 99% RTP, but only at the top stake with its Supermeter, so always read the help screen.

1. Open the game's help or information screen before you spin.
2. Find the RTP and check whether it changes with stake or feature.
3. Work out the average cost: stake per spin × number of spins × house edge.
4. Set a budget you are happy to spend on entertainment, and stop when it is gone.
5. Use the casino's deposit limits and reality checks to keep to it.

Playing slots at UK-licensed casinos

Slot history is our topic here, but if you want to try modern slots, choose a casino licensed by the Gambling Commission so the stake limits, speed rules and game testing above all apply. Browse our slot reviews first, and see the history hub for more background.

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18+. Every casino game has a built-in house edge, so over time you should expect to lose what you stake. Set a budget before you play and stop when it’s gone: safer gambling tools and support. Free, confidential help: National Gambling Helpline 0808 8020 133.