Expanding reels slots start with a small grid and add rows, or whole reels, during play, so the number of ways to win jumps from a few hundred to tens of thousands or more. The stake stays the same while the grid grows, which is why the feature usually sits inside free spins or a feature round.
Expanding reels add rows or reels during a feature, so each spin covers far more ways to win.
Ways grow by multiplication: five reels of three rows give 243 ways, five reels of six rows give 7,776.
Your stake doesn’t rise as the grid grows, but the game’s RTP already prices the bigger grid in.
Slots in our facts that use it include Misery Mining, Cygnus, Phoenix Sun and Fire in the Hole xBomb.
Big ways counts don’t mean frequent big wins; most of the extra ways pay low symbols.
Feature type
Grid or reel-height growth
Usually found
Free spins and respins
Ways maths
Rows on each reel multiplied together
Biggest jump in our facts
Misery Mining: 27 to 823,543 ways
Stake effect
None: cost per spin stays fixed
Volatility
Usually high
What expanding reels slots are
In an expanding reels slot, the playing grid is not fixed. A trigger, such as a scatter, a special symbol or simply entering free spins, raises the height of some or all reels, or adds an extra reel to the side. Because most of these games pay on ways to win rather than fixed lines, every extra row multiplies the number of winning paths.
Developers market the feature under many names: reel expansion, grid growth, WaysBoost, “cells” that open up. They all share the same principle. The grid you see at the start of the round is the smallest it will be, and it can only get bigger until the feature ends. Our slot features hub groups it with the other mechanics that change the shape of the reels, such as Megaways and infinity reels.
The maths behind expanding reels: how ways multiply
On a ways slot, the number of ways equals the number of rows on reel 1 × rows on reel 2 × rows on reel 3, and so on. Add one row to every reel and the total doesn’t just creep up, it multiplies. This table shows a five-reel game growing a row at a time, the same range Phoenix Sun and Dancing Drums cover (243 to 7,776 ways).
Five reels: ways to win as rows are added
Rows per reel
Calculation
Ways to win
Times the 3-row grid
3
3 × 3 × 3 × 3 × 3
243
1×
4
4 × 4 × 4 × 4 × 4
1,024
4.2×
5
5 × 5 × 5 × 5 × 5
3,125
12.9×
6
6 × 6 × 6 × 6 × 6
7,776
32×
Grids that add reels as well as rows grow even faster. Misery Mining starts on a 3 × 3 grid (27 ways) and can reach 7 × 7, which is 7 multiplied by itself seven times: 823,543 ways. Cygnus goes from 4,096 ways on six reels of four to 262,144 ways on six reels of eight.
More ways is not the same as more value. Each way still needs matching symbols from the leftmost reel, and the extra rows are filled mostly with low-paying symbols. The game’s RTP already accounts for the expansion.
How an expanding reels feature plays out
Most games follow a version of this sequence. Every step is part of a result already chosen by the random number generator.
A trigger lands: typically scatters for free spins, or a special symbol that opens new rows.
The grid grows. Reels may rise by one row per trigger symbol, jump to full height, or gain an extra reel.
The new size often stays for the rest of the feature, so later spins run on the larger grid.
Wins are counted across every way on the current grid, at the same stake you started with.
When the feature ends, the grid snaps back to its base size for the next paid spin.
Some games, such as Book of Shadows, let the base game expand: its 5 × 3 grid can grow to 5 × 4 or 5 × 5, moving from 10 to 15 or 20 paylines. Others keep the base game small and save all the growth for the bonus.
Expanding reels slots in our checked data
These slots all use some form of reel expansion. Figures come from our verified slot facts; where a figure is missing, check the game’s help screen.
Row-by-row growth: each trigger symbol raises its reel by one row. Phoenix Sun works this way, climbing from 243 towards 7,776 ways.
Full-height jump: the grid goes straight to its maximum when the feature starts.
Extra reel: a whole new reel is added. Punk Rocker’s sixth reel opens during features, taking it from 243 to as many as 46,656 ways.
Blocked cells that open: positions start covered and open as you collect symbols. Folsom Prison and Misery Mining use this approach.
Grid growth in cluster games: grid slots such as Cubes (5 × 5 up to 11 × 11) expand the play area rather than reel height.
How expanding reels affect volatility and cost
Because the largest grids only appear inside features, a big share of an expanding reels slot’s return is stored in rare rounds. That makes most of these games high volatility: Nolimit City rates Misery Mining High and Folsom Prison Insane. Expect long base-game stretches that return little.
The cost of a spin doesn’t change with the grid. At Misery Mining’s 96.09% RTP, the average long-run cost is 3.91% of what you stake. Over 100 spins at 20p (£20 staked) that is about 78p; at £1 a spin (£100) it is £3.91. The max win of 70,000× is £14,000 at 20p, £140,000 at the £2 limit for players aged 18 to 24, and £350,000 at the £5 limit for those 25 and over. Hitting it is extremely unlikely, and studios cap wins at that figure.
Expanding reels myths
Advantages
True: more rows multiply the number of ways to win.
True: the stake per spin stays fixed while the grid grows.
True: the bigger grid is already priced into the published RTP.
Drawbacks
Myth: 117,649 or 823,543 ways means you win on most spins.
Myth: a grid that nearly reached full size last bonus will reach it next time.
Myth: playing more spins in a row makes expansion more likely.
The number of ways is a measure of possible combinations, not likely ones. A dead spin on a huge grid is still a dead spin, and every spin is independent of the last.
Expanding reels and UK venue machines
There is no direct equivalent on a traditional pub fruit machine, which has fixed physical or screen reels. The nearest relatives are extra reels such as number reels and feature boards that add prize steps. Video-screen machines in betting shops, adult gaming centres and casinos can run modern game content, but they stay within their category limits, for example a £2 stake and £500 top prize for Category B3. Our guide to UK slot machine categories sets out each one.
UK rules and expanding reels slots
Online expanding reels slots supplied to Great Britain run without autoplay, at a minimum of 2.5 seconds per spin and without turbo or slam-stop, under rules in force since 31 October 2021. The Commission’s standard on game rules and the likelihood of winning (RTS 3) (opens in a new tab) requires the rules, including how winners are decided, to be available before you play, which is where the grid sizes and ways counts are explained.
Game libraries change, so search each partner casino’s lobby for the title you want rather than relying on a list. None of our partner offers is tied to an expanding reels slot.
Coral gives 100 free spins when new customers bet £10 on slots (10p spins on selected games, 48 hours to accept, valid 7 days, no wagering on winnings). Ladbrokes gives up to 500 free spins, 50 a day for 10 days, after a £10 deposit and spend on slots, with no wagering. PlayOJO’s 80 free spins are on Big Bass Bonanza, a fixed 5 × 3 game, after a first deposit of at least £10, with winnings paid in cash. All 18+, new customers, full terms apply, and certain payment methods don’t qualify. Coral and Ladbrokes share an operator, so check eligibility before signing up to both.
High-volatility grids can drain a balance quickly. Set a deposit limit first, and use the free National Gambling Helpline on 0808 8020 133 if play stops feeling like entertainment.
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.
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. Decide a budget before you play: plan a slot budget. Free, confidential help: National Gambling Helpline 0808 8020 133.
Frequently asked questions
What does expanding reels mean in a slot?
It means the grid can grow during play. Reels gain extra rows, or the game adds a whole reel, usually during free spins or a respin feature. On a ways-to-win slot each new row multiplies the number of winning paths, so a five-reel game can go from 243 ways to 7,776. The stake stays the same throughout. The ways to win guide explains how ways are counted.
How do you calculate ways on an expanding grid?
Multiply the number of rows on each reel together. Five reels of three rows give 3 × 3 × 3 × 3 × 3 = 243 ways. Make every reel six rows high and you get 6 to the power of 5, which is 7,776. A grid that also adds reels grows faster: seven reels of seven rows is 823,543 ways, the top figure for Misery Mining. See what 243 ways means for a step-by-step explanation.
Do expanding reels cost more to play?
No. Your stake per spin is fixed before the spin and doesn’t change as the grid grows, which is part of the appeal. The value of the bigger grid is already built into the game’s RTP, so it isn’t a free extra: the base game usually pays less to fund it. At a 96% RTP, the long-run average cost is about 4p per £1 staked. Use the slot cost calculator guide to work out your own figures.
Which slots have expanding reels?
In our verified data, examples include Misery Mining, Folsom Prison and Fire in the Hole xBomb from Nolimit City, Cygnus from ELK Studios, Phoenix Sun from Quickspin, Vikings from NetEnt, White Rabbit Megaways from Big Time Gaming and Buffalo Blitz II from Playtech. Each uses a different style of expansion. Check the help screen to see how the grid grows in the version you play. The Misery Mining guide shows one of the largest expansions.
Is a slot with more ways more likely to pay?
Not in the way most people assume. More ways means more possible combinations, and you may see small wins more often, but the game’s overall return is fixed by its RTP. Extra rows are filled mostly with low-paying symbols, and big wins still need high-paying symbols across several reels. A game with 117,649 ways can be more volatile than one with 20 lines. The hit frequency explainer covers how often games pay.
What is the difference between expanding reels and Megaways?
Megaways changes the number of symbols on each reel randomly on every spin, so the ways count rises and falls. Expanding reels only grow, usually during a feature, and stay large until it ends. Some games combine both: White Rabbit Megaways expands its reels in free spins on top of the Megaways engine. The Megaways slot machines page explains the random reel modifier behind Megaways.
Can I make the reels expand more often?
No. Expansion triggers are decided by the random number generator, and nothing about timing, stake pattern or how long you play changes the odds. UK slots have no slam-stop or autoplay, and bonus buy, which in other markets lets players pay to start an expanded feature, isn’t offered at UK-licensed casinos. If someone sells a system to trigger expansions, it doesn’t work. Read can you trick a slot machine for the reasons.
What is the max win on expanding reels slots at UK stakes?
It depends on the game. Misery Mining lists 70,000×, which is £140,000 at the £2 limit for players aged 18 to 24 and £350,000 at the £5 limit for those aged 25 and over. Cygnus lists 5,000×, or £10,000 at £2. These caps are reached extremely rarely, and most sessions lose money over time. The max win caps explainer shows how caps work.
Are expanding reels slots high volatility?
Most are. Because the large grids appear only in features, much of the game’s return is concentrated in rare rounds, which means longer quiet spells in the base game. Nolimit City rates Misery Mining High and Folsom Prison Insane, while Phoenix Sun is listed as medium volatility, so it isn’t universal. Always check the volatility rating in the help screen. Our high volatility slots page explains what to expect.
Do pub fruit machines have expanding reels?
Not in the online sense. Classic pub machines have a fixed set of reels, though many add extras such as number reels and feature boards that change what a spin can pay. Pub machines are usually Category C, limited to a £1 stake and a £100 top prize, so their maths is very different from an online ways slot. The fruit machines guide explains how pub machines work.
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