Four columns, sixteen squares and grids that keep growing, from Pop's fixed 256 ways to Chocolates' 65,536. Five four-reel games compared on return, ways and features.
Four Columns, Sixteen Squares
A 4-reel slot spins four columns instead of the usual five. Today almost every one of them uses a square 4×4 grid: four reels, four rows, sixteen symbols on screen. Big Time Gaming made the shape its own with Donuts, Chocolates, Pop and Fizzy Pennyslot, and NetEnt joined in with Big Bang Boom.
Four of the five pay in ways, so matching symbols on neighbouring reels from the left count wherever they sit. Four symbols a reel across four reels gives 4 x 4 x 4 x 4, which is 256 ways before anything grows. For the more common wide grid, see our 5 reel slots; for the tiny fruit-machine window, our 3 reel slots.
Five Four-Reel Slots Side by Side
Ordered by top return. Casinos can run lower versions, and the game’s help screen shows the figure in use.
| Game | Studio | Ways or lines | RTP | Max win | Volatility | Hit frequency |
|---|---|---|---|---|---|---|
| Chocolates | Big Time Gaming | 256 to 65,536 ways | 96.60% | – | High | – |
| Pop | Big Time Gaming | 256 ways | 96.54% | – | High | 32.98% |
| Donuts | Big Time Gaming | 256 to 2,401 ways | 96.54% | – | High | 29.07% |
| Fizzy Pennyslot | Big Time Gaming | 4 lines | 96.44% | 10,170x | – | – |
| Big Bang Boom | NetEnt | 256 to 10,000 ways | 96.07% | 4,300x | – | 29% |
The quoted ceilings split for three games, so their max-win cells stay empty: Chocolates appears at 65,536x and at 7,920x, Pop at 66,960x and at 47,050x, and Donuts mostly at 40,000x with lower figures elsewhere. Fizzy Pennyslot is rated anything from medium to high, NetEnt publishes no volatility figure for Big Bang Boom, and Chocolates and Fizzy Pennyslot lack a widely quoted hit rate.
Chocolates
The 2020 follow-up to Donuts swaps pastries for a box of chocolates. Each chocolate box can open to reveal up to four matching symbols, so a reel can stretch to sixteen symbols and the ways climb from 256 to 65,536. Free spins start at ten, chocolate boxes stay sticky through the round, and four boxes stacked on one reel retrigger it, with no limit on retriggers. It returns 96.60%, the highest of the five. Other sugary reels are on our sweets and candy slots page.
Pop
The third game in the series, from 2021, and the one that never changes shape. The premium balloon symbols float up from below while the card symbols spin down, and winning symbols pop to make room for new ones. Wilds can carry multipliers of up to 4x. Three or more gold coin scatters bring twelve free spins, where every position on the grid keeps its own multiplier that rises each time a winning symbol lands there, with no cap. It returns 96.54% and, by one count, lands a win on 32.98% of spins.
Donuts
Big Time Gaming’s 2018 original. Donut boxes open into several matching symbols, stretching a reel to as many as seven and the grid to 2,401 ways, and wild multipliers can come out of the boxes too. Free spins retrigger without limit. The top return is 96.54%, some casinos run 96.52%, and Big Time Gaming’s own game page now lists a 96.19% version. A 29.07% hit rate means a win about once every three and a half spins.
Fizzy Pennyslot
The odd one out. This 2024 game sits inside a red soda vending machine and pays on four fixed lines, one per row, and only for four of a kind. A bonus reel beside the grid can drop a multiplier of up to 500x onto a win in its row, or trigger coins that lead to six free spins. Stakes start at 1p, the default return is 96.44%, and the top win is 10,170x.
Big Bang Boom
NetEnt’s 2023 cosmic game starts on a 4×4 grid of 256 ways. Wins at the edge of the grid and bomb explosions unlock rows above and below until it reaches ten rows and 10,000 ways, and opening all ten triggers six free spins. There the grid widens to as many as eight reels, prizes stay in place until the round ends, and bomb blasts can multiply them up to 2,048x. NetEnt lists a 96.07% return, a 4,300x top win and a win on 29% of spins. More space-age reels are on our space slots page.
How a Four-by-Four Grid Grows
Every extra symbol on a reel multiplies the ways. Seven symbols on each of four reels gives Donuts its 2,401, ten rows gives Big Bang Boom 10,000, and sixteen gives Chocolates 65,536. The same arithmetic gives a five-reel, three-row game its 243, as our 243 ways slots page explains.
Pop is the exception. Its grid stays at 256 ways, and the growth happens in the free spins multipliers instead, which is where its bigger wins come from.
Four Lines or 256 Ways
On the same square grid, the pay rules change everything. The three ways games with published hit rates win on roughly 29% to 33% of spins, about one spin in three. Fizzy Pennyslot needs four matching symbols straight across a row, so ordinary wins are much rarer and its bonus reel does most of the paying.
Big Bang Boom and Fizzy Pennyslot both sell a feature buy outside Britain. GB builds leave that option out, so every free spins round on these five has to come from the reels. Games where multipliers do the heavy lifting are collected on our multiplier slots page.
What a Version Swap Costs
Fizzy Pennyslot shows the biggest gap: casinos can run 96.44% or 94%. Over 600 spins at £1 a spin, that is about £21 an hour on average against £36. At the £5 limit for players aged 25 and over it becomes about £107 against £180, and at the £2 limit for those aged 18 to 24, about £43 against £72.
On Donuts the versions sit closer together: at £1 a spin, 96.54% averages about £21 an hour and 96.19% about £23. These are long-run averages, and with high-volatility games like these a single hour can swing far either way.
