Slot Machine Bonus Rounds

Last update: May 5, 2024

You came to the right place

Most articles about slot machines on the Internet are written by people who have no clue what they're talking about, either repeating popular myths or just pulling "facts" out of their asses.  Me, I've done the computer programming for actual slot machines (see here), and for machines I haven't worked on, I cite my sources.  (Other sources you can trust include Michael Shackleford, John Robison, John Grochowski, and Frank Legato.)  So with that out of the way...

Bonus rounds

Early slots had physical reels, usually three of them.  Video slots appeared in the 1980s but didn't get traction until the mid-90s when they introduced the concept of the bonus round, a "game within a game".  Getting certain symbols on your spin would trigger that bonus round, where you'd get to play a second game at no additional cost.  You'd usually win something in the bonus round, and you could never lose.  The game that popularized bonus rounds was Reel 'em In by WMS Gaming, where the bonus round has the player trying to catch a fish (through free spins), with the bigger the fish caught, the bigger the payout.  The game was popular, and the concept stuck:  nearly every modern video slot has some sort of bonus round. (source

Bonus rounds are usually triggered by getting 3 or more "scatter" symbols somewhere on the screen.  They're called "scatter" symbols because they don't have to be on an active payline; if they appear anywhere on the screen, they count.

Bonus rounds come in various flavors, depending on the machine:

  1. A certain number of free spins.  And in most games, getting more scatter symbols during free spins, wins more free spins.  Often, wins on free spins are increased by a bonus multiplier.
  2. A screen giving you various choices (such as picking one or two treasure chests out of many).  A common question about this type of game is, does the player really have free will?  Meaning, if the player picks two chests and wins prizes of 10 and 25, was it going to be 10 and 25 no matter which chests she picked?  The answer is that if the game shows you the values of all the unpicked items after you picked, then you really did have free will, and would have won the amounts shown on the unpicked items, had you picked them.  If the game doesn't show you the value of the unpicked items after you pick, then the result was predetermined.
  3. Some animation where you watch some short story play out, and it tells you what you won at the end.

How much of the RTP is from the base game and how much is from the bonus round?

If you've wondered about this or thought to ask this question, then congratulations: you're way ahead of others on understanding the workings of slot machines.

Most video slots pay out about 2/3 of their RTP is the base game (the normal game), and about 1/3 in the bonus.  Here's a list of the split on various actual slots.  And by the way, this aggregated list is the kind of thing you get here at Easy Vegas, and exactly nowhere else.

RTP split between base game/bonus game
Slot % of RTP
from base game
% of RTP
from bonus round
Total game RTP*
Lucky Larry's Lobstermania 65% 35% 92.5%
Lucky Larry's Lobstermania 68% 32% 85%
Jackpot Party
Money Storm
Triple Double Diamond with Hot Roll
Source for data.
• Many slots pay a prize (a "scatter pay") just for landing the symbols to enter the bonus round.
    I'm counting these scatter pays as part of thebonus round winnings.
• Figures are rounded.
* Slots with the same name are usually offered in various RTP flavors by the manufacturer.
    So, it's not that "Money Storm" is a 92.5%, machine, it's that this particular flavor of Money Storm is 92.5%.

Play slots online

I suggest you play something other than slots because slot odds are so bad.  You could also play online with fake money, because then it doesn't matter if you lose.  A good casino for free-play is Bovada, since it requires no download and no registration.  (If you see a registration box, you can close it and continue without registering.)  You can play with real money too, though I hope you won't (or at least won't bet more than you can comfortably afford to lose). (advertisement)

All my slot machine articles

Practice gambling with play money

Before you throw down your hard-earned cash in a casino, PRACTICE FIRST!  Learn the games with play money where it doesn't cost you anything if you lose.  Seriously.

You can play Bovada's games (below) right away without registering for an account.  Most every other online casino makes you give up your email address just to play the fake-money games — ugh.  That's the main reason Bovada is the only online casino that gets advertising space on my site.  (When you see the registration box, you can cancel it and proceed to the game without registering.)

Play blackjack


Play roulette


Play craps


Play baccarat


Approved by Casinomeister

Proud not only to be an approved Webmeister by Casinomeister,
but also to be one of the very first approved. (#7, May 2020)

Site Contents ©2001-2024 Michael Bluejay Incorporated.
I believe everything herein to be accurate, but I'm not responsible for errors or omissions.  I'm pretty irresponsible, actually.

Home |  About Us   Contact  |  Updates  |  Privacy          Gambling Problem? Call the 800-522-4700 hotline, see horror stories, and know that aripiprazole and Parkinson's drugs encourage gambling.

Play:  Slots  •  Blackjack  •  Craps  •  Roulette