Jackpot: meaning and how it works

What a jackpot means in a casino

In everyday use, any big win gets called a jackpot. In game rules the word is narrower: it names the top prize on a slot or machine, the best-paying hand in video poker or the highest tier of a side bet. Our casino glossary lists it beside multiplier and payout, which often describe how the top prize is calculated.

Jackpots are the part of a game most likely to be misunderstood. A large advertised figure tells you what one player may receive, not what a typical session returns. The game’s RTP remains the better guide to cost.

Fixed, progressive and must-win jackpots

Our feature page on progressive jackpots goes deeper into networks, and the royal flush entry covers the video poker version.

How a progressive jackpot grows and resets

A progressive pot rises by a fixed share of each qualifying stake. If 1% of every stake is added, £100,000 of play across the network adds £1,000 to the pot. When someone wins, the jackpot drops back to its seed value and starts climbing again. The Gambling Commission’s RTS 9 standard for progressive jackpots (opens in a new tab) requires the rules to explain how the pot is funded and what the seed and any ceiling are.

1. Open the game’s help screen and find the jackpot section.
2. Check whether every stake size is eligible or only some.
3. Note the seed value, any cap and whether the RTP figure includes the jackpot contribution.
4. Compare that RTP with a non-jackpot slot before choosing.

RTS 9 also says the chance of winning a jackpot should rise in line with the amount contributed, so on many games a 10p spin has a smaller jackpot chance than a £1 spin. The progressive jackpot maths page shows why the effective return is lower when a pot sits near its seed.

What jackpot slots cost: a worked example

The jackpot is funded by players, so part of the RTP is paid out rarely, as one huge prize. The developer figures below show how much that can shift the everyday return.

Take 100 spins at 50p, £50 staked. At 90.3% the average cost is £50 × 9.7% = £4.85, and 5.3 points of that return (about £2.65 of the £50) sits in the jackpot rather than in everyday wins, leaving 85% for the base game. At Starburst’s 96.09%, the same £50 costs £1.96 on average. Neither figure predicts one session, but the gap shows what the chance at a big pot costs.

Record jackpots and what they really tell you

On 20 December 2023 Wheel of Wishes paid a WowPot! jackpot of €38,461,200.95, which iGaming Business reported (opens in a new tab) as the largest online slot jackpot win. Before that, a Belgian player won more than €19.4 million on Absolootly Mad Mega Moolah in April 2021 from a €15 stake.

These wins are real, but they are one result among millions of spins that funded them. A record pot is evidence that the network was large, not that a jackpot is close. Spins have no memory, so a pot that has not paid for months is not ‘due’; our gambler’s fallacy page explains why.

UK rules that apply to jackpots

• Jackpot rules must be available before you commit to gamble, and current values shown to eligible players (RTS 9).
• If you are not eligible for a game’s progressive at your stake, that must be made clear.
• Online slot stakes are capped at £5 a spin, or £2 for 18 to 24-year-olds, jackpot games included; see slot stake limits.
• Winnings are not taxed for UK players; our answer on tax on casino winnings explains why.

For how big wins are paid and checked, read how jackpots are paid out and whether you can win a jackpot with free spins.

Jackpot games and our partner offers

Two of our partner offers are slot-based, but none promises access to a particular jackpot game, so check each casino’s game lobby and the eligible-games list in the terms. 18+ and terms apply.

• Casumo gives new customers who opt in a 50% bonus up to £100 on a first deposit of £20 or more; wager it 10x within 7 days, stay at or under £5 a bet while it runs, and expect game, play and payment restrictions.
• 10bet matches a first deposit 100% up to £25 for new UK customers who choose the casino welcome bonus at sign-up and deposit within 7 days; wagering is 10x on slots within 3 days, bonus winnings stop at £1,000, and Skrill and Neteller deposits don’t count.
• Coral: deposit and bet £10 or more on slots as a new player to get 100 free spins at 10p on selected games, accepted within 48 hours and valid for 7 days, with spin winnings paid without wagering; Neteller, PayPal, Paysafe, Skrill, prepaid cards and certain debit cards are excluded, and the offer runs until 1 February 2027.

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.