Expanding wild meaning: an expanding wild is a wild symbol that grows to cover every position on its reel when it lands, turning one wild square into a full wild column. Because every payline through that reel now passes a wild, it can complete several wins at once. Starburst, where expansion also triggers a respin, is the best-known example.
An expanding wild grows to fill its whole reel, so every line through that reel gets a wild.
Some expand every time they land; others expand only if that completes a win.
Starburst’s wilds land on reels 2–4, expand, stay and trigger a respin, up to three times.
Expanding wilds are different from Book of Dead’s expanding symbol and from reels that add rows.
Definition
Wild that grows to cover its reel
Effect
Every line through that reel gets a wild
Common add-on
Respin with the wild reel held
Best-known example
Starburst (NetEnt)
Related
Sticky wild, walking wild
Expanding wild meaning: one symbol, one whole reel
On a standard 5 × 3 slot a reel shows three positions. When an expanding wild lands on any of them, an animation stretches it to cover all three, and the game treats the whole reel as wild before paying. On a payline slot, every line that crosses that reel now has a wild on it. On a ways to win slot, the reel contributes a wild to every possible way.
Studios set two separate rules, and both appear in the help screen. The first is when it expands: always, or only when expanding would complete a win. The second is what happens next: nothing, a respin with the wild reel held, or the wild staying for later spins, which overlaps with the sticky wild idea.
The Starburst example, step by step
NetEnt lists expanding wilds among its signature mechanics, and Starburst is the reason. Its rules are a clean model of the feature:
Wilds can only land on reels 2, 3 and 4.
When a wild lands, it expands to fill its reel.
The expanded reel stays in place and the other reels respin once, at no extra stake.
If another wild lands on a free reel during the respin, it expands too and grants another respin.
The most that can happen is three wild reels and three respins, after which the feature ends.
Starburst has 10 paylines that pay both ways and a published RTP of 96.09%, with a max win of 500× stake. That low ceiling reflects how frequent its feature is: wilds land often, but each expansion pays modestly. It is a useful contrast with games where an expanding wild is rare and carries a multiplier.
Expanding wild meaning in pounds: line maths
Take an illustrative 10-line slot at £1 total stake, so 10p a line. Three of the ten lines pass through the top, middle and bottom of reel 3, and the other seven zigzag through it too, because every line must cross every reel. When reel 3 turns wild, all ten lines get a wild in the middle position.
One expanding wild on reel 3, illustrative 10-line slot at £1
Line result after expansion
Lines
Pays per line
Total
Three low symbols (incl. wild)
4
5× line bet = 50p
£2.00
Three high symbols (incl. wild)
1
10× line bet = £1
£1.00
No match beyond the wild
5
Nothing
£0.00
Spin total
10
£3.00
Without expansion, the single wild would have helped only one or two lines. The comparison explains why the feature matters to the game’s design, and why studios balance it with lower symbol payouts elsewhere: the house edge stays the same, and the RTP includes every expansion.
Expanding wild vs expanding symbol vs expanding reels
Expanding symbol. In Book of Dead’s feature, one regular symbol is chosen to expand across its reels when enough of it lands. It does not substitute for anything; it only grows. Many book-style slots copy this.
Expanding reels or rows. Some games add rows during a feature so the grid itself gets bigger. Book of Shadows, for example, can expand from 5 × 3 to 5 × 4 or 5 × 5. That changes the number of lines or ways, not what any symbol does.
Colossal or stacked wilds. These land already covering several positions. The result can look like an expansion, but there is no growth step.
When a help screen says ‘expanding’, check which of these it means. The slot features explained guide sets them side by side.
UK rules that affect expanding wild features
A respin triggered by an expanding wild is part of the same game cycle as the spin that caused it, so it does not take a new stake and sits within the stake limit of that spin: £5 for players aged 25 and over since 9 April 2025, and £2 for players aged 18 to 24 since 21 May 2025. The £2 slot stake limit page explains how casinos apply the age band.
The animation of a wild growing cannot be skipped. Since 31 October 2021, UK slots have had no turbo, no slam-stop and no autoplay, and they must not celebrate a return equal to or smaller than the stake, as the Commission set out in its summary of changes to the technical standards (opens in a new tab). So an expansion that returns 80p on a £1 spin should not be presented with winning fanfare. The slam stop and turbo spin entries explain those banned features.
Glossary terms near expanding wild
Wild: the parent term, with all wild types listed.
No partner offer is built around an expanding-wild game. At Coral, new players aged 18+ who deposit and stake £10 or more on slots receive 100 spins worth 10p each on selected games, to be accepted within 48 hours and played within 7 days; winnings from them carry no wagering, and deposits made by PayPal, Neteller, Skrill, Paysafe, prepaid card or certain debit cards are excluded. PlayOJO gives new UK customers aged 18+ (not Northern Ireland) 80 spins at 10p on Big Bass Bonanza after a first deposit of at least £10, with no wagering. Terms apply. If play stops feeling like entertainment, the NHS gambling support page (opens in a new tab) explains how to get free help.
Neither offer is tied to an expanding-wild slot: Coral gives 100 spins at 10p on selected slots after a £10 slots bet, and PlayOJO gives 80 spins at 10p on Big Bass Bonanza after a £10 first deposit. 18+, terms apply; 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 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.
18+. Gambling should be entertainment that costs money, not a way to make it. Set a deposit limit before you play: how to set deposit limits. Free, confidential help: National Gambling Helpline 0808 8020 133.
Frequently asked questions
What does expanding wild mean?
An expanding wild is a wild symbol that grows to cover its entire reel after it lands. Once the reel is fully wild, every payline or way that passes through it can use the wild to complete a win. Some games expand the wild every time, while others expand it only if that creates a win. The wild entry covers substitution rules, and how to read a slot paytable shows where expansion rules are written.
How do Starburst wilds work?
Starburst’s wilds can land only on reels 2, 3 and 4. When one lands it expands to fill the reel, stays in place, and the other reels respin once at no extra cost. A new wild during the respin expands too and gives another respin, up to a maximum of three wild reels. The game has 10 lines that pay both ways and a published RTP of 96.09%. The Starburst spins offers page covers current offers on the game.
Is an expanding wild the same as an expanding symbol?
No. An expanding wild substitutes for other symbols and grows to fill its reel. An expanding symbol, as in Book of Dead’s feature, is a regular symbol that grows across its reels to create more wins but does not substitute for anything. Both can look similar on screen, so the help screen wording matters. Slot features explained compares the two alongside expanding grids.
Do expanding wilds trigger a respin?
Some do and some do not. In Starburst every expansion triggers a respin with the wild reel held, but in many other slots the wild simply expands for that spin’s result and the next spin is a normal paid spin. A respin from an expanding wild costs nothing extra and counts as part of the same game cycle for UK stake-limit purposes. The spin speed limit page explains how game cycles are timed.
Are expanding wild slots low volatility?
Not necessarily, though the best-known example is. Starburst pairs frequent expanding wilds with a 500× stake max win, which places it at the lower-volatility end. Other games make expanding wilds rare and add multipliers, which pushes volatility up. The feature itself does not decide the rating; the frequency and size of its payouts do. The volatility glossary entry explains what the label measures and why it matters for your budget.
Can expanding wilds land in the bonus round?
Yes, and many games make them more common there. A slot might expand wilds only during its feature, or add a multiplier to expanded reels in the feature. Feature spins are played at the stake of the spin that triggered them, so the UK stake limits still apply. Because bonus buys are not offered to British players, you reach the feature by triggering it in play. The bonus round entry covers how features are triggered.
Gambling can be addictive. Free, confidential help is available 24 hours a day from the National Gambling Helpline on 0808 8020 133. Get free support from GamCare or NHS gambling support, or block yourself from all UK-licensed gambling sites with GAMSTOP.
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