In slots, jackpot contribution means the slice of every stake that goes into a progressive or pooled jackpot rather than paying ordinary wins. It is counted inside the game's RTP, so a jackpot slot quoting 93% might return about 88% through normal play and set aside about 5% for the pot that very few players will ever win.
Every progressive jackpot needs feeding. The feed is the jackpot contribution: a fixed share of each stake, set by the game's designer, that is added to the pot (and often to a hidden reserve that pays the next jackpot seed). If the contribution is 5% and you stake £1, 5p goes towards jackpots and 95p is handled by the rest of the game's maths. You can find this and related terms in our slot glossary.
The contribution does not come from the casino's margin. It comes out of the return to player. Think of a jackpot slot's RTP as two buckets: the base game bucket, paid out through line wins and features, and the jackpot bucket, paid out in rare, large lumps.
Jackpot contribution in real slots
Published figures show how big the jackpot bucket can be. The table uses figures from game specifications and slot reference sites; where sources give a split, the jackpot share is shown.
RTP with and without the jackpot share
Slot
Developer
RTP figures
Jackpot share
Mega Moolah
Games Global
88.12% base game; about 93.42% including jackpots (OLBG)
About 5.3 points
Mega Moolah 4Tune Reels
Games Global
90.3% including jackpots
5.3%
Divine Fortune
NetEnt
96.59% including jackpot; 92.52% excluding (OLBG)
About 4.07 points
King Kong Cash Even Bigger Bananas
Blueprint Gaming
96% standard; 94.99% Jackpot King version
Not published; versions differ by about 1 point
Two lessons stand out. First, Mega Moolah returns 88.12% from its base game, well below a typical video slot, because so much is reserved for its pots. Second, Divine Fortune has a healthy headline RTP but a lower base return once the jackpot share is set aside. Other jackpot games such as Age of the Gods (95.02%) quote an RTP that already includes the contribution.
Worked example: what the contribution means for your session
Take 100 spins at 25p on a game like Mega Moolah: £25 staked. At the 88.12% base return, ordinary wins hand back £22.03 on average, so the average cost of the session from the base game is about £2.97. A further 5.3% of the £25, about £1.33, goes to the jackpots. Unless you win one, that money is not coming back to you in this session.
100 spins at 25p (£25 staked): base game against jackpot share
Bucket
Share of stakes
Average amount
Base game returns
88.12%
£22.03
Jackpot contribution
about 5.3%
about £1.33
House edge
about 6.58%
about £1.64
Total
100%
£25.00
Compare a non-jackpot slot at 96% RTP: the same £25 would cost £1 on average. The difference is the price of a ticket in the jackpot draw. Our slot cost calculator lets you try other stakes and RTPs, and the house edge page explains the last row.
Open the game's help or rules screen before playing.
Look for the RTP figure and whether it says including or excluding jackpots.
If both are given, subtract to find the jackpot share.
Use the base figure to estimate your typical session cost.
Treat the jackpot share as the cost of a very long-shot chance, not as money you are likely to see again.
In land-based casinos, Category B1 machines can link to a progressive jackpot of up to £20,000, but only within one premises, according to the Commission's gaming machine categories page (opens in a new tab). Contributions on those machines come from stakes on the linked machines in that building. Our linked progressives page explains the set-up.
Jackpot contribution myths
Higher stakes do not always buy a bigger share of the jackpot chance. On some games they do; on others the chance is fixed per spin. The help screen says which.
A huge pot does not mean contributions are generous. It usually means the pot has gone a long time without being won.
The contribution is not lost to players as a group. It is paid back when the jackpot lands, just to one person; read how slot jackpots get so big.
Jackpot networks and their games differ between casinos and change often, so search each lobby and confirm the RTP version in the help screen. The Ladbrokes jackpot slots page gives an overview for that brand. The partner offers below are for new customers aged 18 or over; terms apply.
Ladbrokes: play £10 on slots and receive 50 free spins each day for ten days, up to 500, worth 10p each; claim each batch by 23:59, use it within seven days, and keep winnings without wagering. Prepaid cards, PayPal, Paysafe, Neteller, Skrill and Moneybookers deposits do not qualify. Coral: from 1 October 2026 to 1 February 2027, a qualifying deposit and £10 bet on slots brings 100 free spins at 10p on selected games, to be accepted within 48 hours and used within seven days, with no wagering on winnings. Selected games for spins often exclude progressive titles, and both brands sit under LC International Limited, so check whether one person can claim both.
Coral and Ladbrokes are both run by LC International Limited (Entain). If you already hold an account with one Entain brand, you may not be able to open a new account with another; check the terms before signing up.
Significant terms: 18+. New players only. Offer runs 01/10/2026 to 01/02/2027. Deposit (certain types excluded) and bet £10+ on slot games to get 100 free spins (selected games, £0.10 each, 48 hrs to accept, valid 7 days). No wagering on free spin winnings. Deposits by Neteller, PayPal, Paysafe, Skrill, prepaid cards and certain debit cards do not qualify. Restrictions and T&Cs apply. GamCare.org.uk
Read the Coral reviewLicence: LC International Limited, UKGC account 54743. Offer checked 5 October 2026.
Significant terms: 18+. New customers only, from 14/11/25 until further notice. Certain deposit methods excluded. Deposit and spend £10+ on slots for 50 free spins a day during the first 10 days after first deposit and registration (max 500, £0.10 each, selected games, claim before 23:59 each day, valid 7 days). No wagering. Prepaid cards, PayPal, Paysafe, Neteller, Skrill and Moneybookers deposits do not qualify. Restrictions and T&Cs apply. GamCare.org.uk
Read the Ladbrokes reviewLicence: LC International Limited, UKGC account 54743. Offer checked 5 October 2026.
18+. Gambling should be entertainment that costs money, not a way to make it. Decide a budget before you play: plan a slot budget. Free, confidential help: National Gambling Helpline 0808 8020 133.
Frequently asked questions
What is a jackpot contribution in slots?
It is the share of every stake that goes into a progressive or pooled jackpot. If a game contributes 5%, then 5p of each £1 spin funds the pot and the rest goes through the normal maths of the game. The contribution is part of the RTP, so the base game pays back less than the headline figure suggests. Our explainer on how slot jackpots are funded shows where contributions go and how resets are paid for.
Is the jackpot contribution included in RTP?
Yes. The full RTP of a jackpot slot is the base-game return plus the jackpot share. Mega Moolah, for example, returns 88.12% from its base game and about 93.42% including jackpots, according to OLBG. Some sources quote one figure, some the other, so check whether a number says including or excluding jackpots. Our guide to RTP explains why it is a long-run average over millions of spins rather than a forecast for one session.
Why do jackpot slots have lower RTP?
Often they do not have lower total RTP, but they have a lower base-game return, because part of the RTP is set aside for the jackpot. Since only a tiny number of players win the top pot, most players experience something close to the base figure. That makes jackpot slots more expensive on average for a typical session. Our high RTP slot machines page explains how to compare headline figures fairly across very different games.
Do I contribute more to the jackpot if I bet more?
In pounds, yes: a 5% contribution takes 10p from a £2 spin and 5p from a £1 spin. Whether a higher stake also improves your chance of winning the jackpot depends on the game; some scale the chance with stake, others do not. The help screen should say which. UK stake limits of £5 a spin for over-25s and £2 for 18 to 24-year-olds apply either way. Our page on whether you should bet max looks at this in more detail.
How can I find a slot's jackpot contribution?
Open the help, rules or paytable screen and look for the RTP statement. Many jackpot games state the total RTP and either the base-game figure or the jackpot share. If only one figure appears, the rules should still explain whether the game contributes to a jackpot. Slot reference sites sometimes publish both figures too. Our step-by-step guide on how to find a slot's RTP shows where these menus usually sit on desktop and mobile.
Where does the contribution go if nobody wins?
It stays in the pot, which is why progressive jackpots can grow so large. Some of it may also sit in a seed reserve that pays to restart the jackpot after a win. The money is eventually paid out to whoever wins the pot, so across all players it is returned, just very unevenly. If a game is withdrawn, its rules should explain what happens to the pool. Read our jackpot seed entry for how resets are funded.
Gambling can be addictive. Free, confidential help is available 24 hours a day from the National Gambling Helpline on 0808 8020 133. Visit GamCare.org.uk and GamCare, or block yourself from all UK-licensed gambling sites with GAMSTOP.
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