What is a slot bonus round? It is a special feature, triggered during normal spins, that switches the game into a different mode with its own rules: free spins, a pick-and-click game, a hold-and-win respin or a prize wheel. On most modern slots, the bonus round is where the biggest wins come from, and a large share of the game’s return is paid there.
A bonus round is a separate mode inside a slot, usually triggered by scatter or bonus symbols.
Free spins, pick-me games, hold-and-win respins and wheels are the main types.
Bonus rounds are random: no slot is ever ‘due’ to trigger one.
Buying a bonus round isn’t allowed for players in Great Britain.
Usual trigger
3+ scatter or bonus symbols
Main types
Free spins, pick-me, hold and win, wheel
Cost
Nothing extra once triggered
Bonus buy in Great Britain
Not offered
Where rules are shown
The game’s help screen
Slot bonus round: what it is in plain terms
Most of the time a slot runs its base game: you pay for a spin, the reels stop, and any matching symbols pay. A bonus round interrupts that. When the right symbols land, the game switches into a different mode with different reels, new rules or extra mechanics, plays it out, then returns you to normal play with the total added to your balance.
You don’t pay extra for the bonus round once it triggers. It is part of the spin that set it off, which is why the win from a whole feature counts as one spin’s result. The bonus round glossary entry has the short definition, and base game explains the mode you return to.
The main types of slot bonus round
Studios invent new names constantly, but nearly every bonus round is a version of one of these.
Type
How it plays
Well-known example
Free spins
A set number of spins at no cost, often with an extra twist such as multipliers or special symbols
Many slots combine types: a free spins round that also contains a pick-me to choose your multiplier, for example. Our guide to slot features explains the building blocks, and the pick-me bonus and hold and win glossary entries go into detail on those two.
How a bonus round is triggered
The most common trigger is three or more scatter symbols anywhere on the reels. Some games use a dedicated bonus symbol that must land on specific reels, often reels 1, 3 and 5. Others trigger at random after any spin, or fill a meter over many spins.
Whatever the visible trigger, the outcome is decided by the random number generator at the moment you spin. Near misses, where two scatters land and the third just misses, are not evidence that the bonus is close. Our how slot features trigger guide explains how this works under the bonnet.
Feature frequency: how often bonus rounds arrive
Some developers publish the average number of spins between bonus rounds, called feature frequency. Suppose a game lists one bonus every 200 spins on average. At 20p a spin, that is £40 of stakes between features on average, but averages hide a wide spread: you might trigger it on spin 12 or wait 700 spins. Budget for the long end, not the average.
What a bonus round pays, and why it matters
On most modern video slots, a large slice of the RTP is paid inside bonus rounds rather than the base game. That has a direct effect on how a session feels. If, say, a third or more of a game’s return comes from features, the base game has to pay less, which means more dead spins and more small returns below your stake while you wait.
It also means bonus round results vary enormously. A free spins round can pay less than the stake that triggered it, or hundreds of times it. A useful habit is to judge a feature by its pay as a multiple of stake: a 20x bonus at 50p is £10, while a 200x bonus at 50p is £100. The same game can produce both.
A bonus round that pays less than the total you spent getting to it is common. Over time, the house edge applies to the game as a whole, bonus rounds included.
Worked example: a free spins bonus round in pounds
Take a 10-payline slot with a 5,000x max win, played at 50p a spin. Three scatters land on spin 140, after £70 of stakes, and award 10 free spins with an expanding symbol, the format used by Book of Dead.
Spins 1 to 6 pay a few small line wins totalling £3.
Spin 7 lands three of the expanding symbol, which fill their reels and pay across all 10 lines: £25.
Spins 8 to 10 pay nothing.
Bonus total: £28, or 56x the 50p stake.
The feature felt good, but the session is still £42 down. That is the normal pattern. Occasionally a bonus round pays far more than the stakes that preceded it; more often it recovers only part of them.
Bonus round free spins versus casino free spins
The phrase ‘free spins’ means two different things. In-game free spins are a bonus round triggered by the slot itself. Promotional free spins are spins a casino credits to your account as part of an offer, usually after a deposit or a qualifying bet. Promotional spins are ordinary base-game spins at a fixed value, often 10p, and they can trigger the slot’s own bonus round like any other spin.
No bonus buy: the option to pay a multiple of your stake to jump straight into a bonus round isn’t offered to players in Great Britain. Read more on bonus buy slots.
No autoplay or turbo: you must start each base-game spin yourself, and each must last at least 2.5 seconds. Bonus rounds still play out automatically once triggered.
No celebrating small returns: a bonus round that pays less than your stake mustn’t be presented as a win with celebratory sounds or graphics.
Stake limits still apply: £5 a spin for players aged 25 and over, £2 for those aged 18 to 24.
How to judge a slot’s bonus round before you play
Open the game rules and read exactly how the bonus round triggers and what it contains.
Check the volatility rating: a high volatility slot usually has rarer but stronger bonus rounds.
Look for a published feature frequency or hit rate, if the developer gives one.
Note the max win, which caps the bonus round as well as the base game.
Try the demo after age verification to see how long the gaps between bonus rounds feel at your stake.
PlayOJO’s welcome spins are on Big Bass Bonanza, so they can trigger its free spins round. Coral and Ladbrokes credit spins on selected games after a £10 slots bet. All three pay spin winnings with no wagering. 18+, new customers, terms apply.
PlayOJO’s 80 free spins (10p each, after a £10+ first deposit) are on Big Bass Bonanza, a slot whose free spins round is described on this page; winnings are paid as cash. 18+, T&Cs apply.
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 UK customers (excluding Northern Ireland). First deposit only. Minimum deposit £10. 80 free spins on Big Bass Bonanza, £0.10 each. No wagering requirements; winnings paid in cash. Cannot be used with any other offer. Only available to players who arrive through the designated offer link. Full T&Cs apply. GamCare.org.uk
Read the PlayOJO reviewLicence: Skill On Net Limited, UKGC account 39326. Offer checked 5 October 2026.
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. Set a deposit limit before you play: how to set limits. Free, confidential help: National Gambling Helpline 0808 8020 133.
Frequently asked questions
What is the difference between a bonus round and free spins?
Free spins are one type of bonus round, the most common one. A bonus round is any special mode a slot switches into, including pick-me games, trails, wheels and hold-and-win respins as well as free spins. To add to the confusion, casinos also give promotional free spins, which are ordinary paid spins credited as part of an offer. Our free spins feature glossary entry explains the in-game version, and the slot features guide covers the rest.
How do you trigger a bonus round on a slot?
You trigger a bonus round by landing the required symbols during a normal spin, most often three or more scatter symbols anywhere on the reels. Some slots use a bonus symbol on specific reels, a random trigger or a meter that fills over time. The exact rule is in the game’s help screen. You can’t make a bonus round more likely by changing stake or timing. Our guide to how slot features trigger explains why.
Can you buy a bonus round in the UK?
No, players in Great Britain can’t buy a bonus round. The bonus buy option, where you pay a multiple of your stake to enter a feature directly, isn’t offered on UK versions of slots. If you see a demo with a buy button, it is an international version. In the UK the bonus round has to be triggered naturally through normal spins. Our page on whether you can buy bonuses on UK slots explains the background.
How often should a slot bonus round trigger?
There is no set rule: each slot has its own feature frequency, and some developers publish it as an average such as one bonus every 150 or 200 spins. That average hides big variation, so you may wait several times longer than the figure suggests. High volatility slots tend to have rarer bonus rounds than low volatility ones. Budget for the longer gaps. Our feature frequency entry explains how the figure is calculated and where to find it.
Do bonus rounds pay more than the base game?
On most modern video slots, yes: bonus rounds pay a large share of the total return, and the biggest wins usually happen there. That doesn’t mean every bonus round is profitable; many pay less than the stakes spent waiting for them. The base game on these slots pays less often or in smaller amounts to make room for the feature. Our slot maths models guide explains how studios split the RTP between base game and features.
Is a bonus round more likely after a long time without one?
No, a bonus round isn’t more likely just because it hasn’t triggered for a while. Every spin on a licensed slot is independent, decided by the random number generator, so the chance of a trigger on the next spin is the same whether the last bonus was 10 spins ago or 1,000. Believing otherwise often leads to chasing losses. Our page on why slots are never due a win explains the maths.
Can a bonus round lose money?
A bonus round can’t take money from your balance once it has triggered, because the spins or picks inside it are paid for by the spin that set it off. It can, however, pay less than that spin’s stake, and very often pays less than the total you spent getting to it. That is why it is better to judge a session by your net position rather than by whether you triggered the bonus. See our net position display entry.
Which slots have the best bonus rounds?
There isn’t a single best: it depends on whether you prefer frequent modest features or rare, high-ceiling ones. Classic free spins with an expanding symbol, as in Book of Dead, suit players who like a clear, simple feature. Collect-style rounds such as Big Bass Bonanza’s are popular for their visible build-up. Hold-and-win games like Wolf Gold give a different rhythm. Our guide to the best slots with free spins features compares several.
Gambling can be addictive. Free, confidential help is available 24 hours a day from the National Gambling Helpline on 0808 8020 133. Get support from GamCare or NHS gambling support, or block yourself from all UK-licensed gambling sites with GAMSTOP.
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