Double-up Feature in Online Slots

Double-up (Gamble) Feature Explained + Best Paying Slots

Double-up (sometimes it is called “gamble”, "risk" or the other names with a similar meaning) feature does not affect RTP (Return to Player %) or House edge of online casino slot. Hence, it is pretty much neutral in terms of increasing or decreasing your winning chances.

Best Paying (RTP) Online Slots with Double-Up feature

(Players from United States are welcome)

Casanova's Ladies Online Slot Logo
RTP: 97.1 %
Double-Up: Yes
Big Red Online Slot Logo
RTP: 97.04 %
Double-Up: Yes
Classic 243 Online Slot Logo
RTP: 97.0 %
Double-Up: Yes
Pearl Lagoon Online Slot Logo
RTP: 96.88 %
Double-Up: Yes
Millionaire Mystery Box Online Slot Logo
RTP: 96.64 %
Double-Up: Yes
Rise of Merlin Online Slot Logo
RTP: 96.58 %
Double-Up: Yes
Arabian Spins Online Slot Logo
RTP: 96.55 %
Double-Up: Yes
Da Vinchis Treasure Online Slot Logo
RTP: 96.53 %
Double-Up: Yes
Fairytale Fortune Online Slot Logo
RTP: 96.52 %
Double-Up: Yes
Xmas Magic Online Slot Logo
RTP: 96.5 %
Double-Up: Yes
The Great Chicken Escape Online Slot Logo
RTP: 96.5 %
Double-Up: Yes
Relic Hunters and the Book of Faith Online Slot Logo
RTP: 96.37 %
Double-Up: Yes
Dragons Lucky 8 Online Slot Logo
RTP: 96.34 %
Double-Up: Yes
Telly Reels Online Slot Logo
RTP: 96.29 %
Double-Up: Yes
Beauty Fruity Online Slot Logo
RTP: 96.27 %
Double-Up: Yes
Gem Splitter Multiways Online Slot Logo
RTP: 96.27 %
Double-Up: Yes
Butterfly Lovers Online Slot Logo
RTP: 96.25 %
Double-Up: Yes
Fisherman's Bounty Online Slot Logo
RTP: 96.25 %
Double-Up: Yes
Neon City Online Slot Logo
RTP: 96.25 %
Double-Up: Yes
Torro's Gold Online Slot Logo
RTP: 96.24 %
Double-Up: Yes

Full list of slots with gamble feature

However, the double-up could significantly increase the volatility level of such an online slot.

Further, I will try to elaborate on both statements alongside with other specifics of this feature. By the way, I've interviewed the webmaster of, who was wearing his best bjj gi for the occasion.

In this article:

1) What is the Double-up feature in online slots?

2) How exactly the double-up get implemented in online casino slots

3) Why it does not affect your chances of winning in online slot?

4) When the Double-up feature could be harmful for online casino players?

What is the Double-up feature in online slot?

The double-up feature could be called differently depending on a particular online slot producer. You could come across other names such as “gamble”, “risk” and others.

It does not matter how they call it; everything comes down to these characteristics which distinguish the double-up feature:

  • it can be used only after you have hit some winning in online slot

  • the limited number of possible outcomes. You either double-up (quadruple-up in some cases) or lose

Let’s dive deeper into each of them.

Whenever you hit any winning at online slot with the double-up feature, it makes you decide whether you want to collect the winning and continue to play in casual mode or to risk in order to double (or quadruple) the winning.

If you are lucky enough and manage to double the winning then the online slot gives you the same choice again. At this point, you can collect doubled winning or risk again, and so on.

I would like to mention that some online slots allow to double-up only winnings derived from pay-lines, but some of them let you do so with Bonus game and Free spins winnings as well.

The double-up feature is designed only in addition to main features. So, I guess, it would be unfair to expect it to be super fascinating at any extent. So to speak, options of the player are limited to these:

  • the initial winning is doubled

  • the initial winning is quadrupled

  • the player loses the initial winning

  • the player collects the initial winning and continues to play in usual mode

How exactly the double-up get implemented in online casino slots

When the winning happens, you are going to be provided with option to double-up or collect the winning. Press the button that matches your choice.


The image of Rise of Merlin slot (PlayNgo)

Then, if you decided to try your luck, almost certainly, you are going to interact with a deck of cards in one form or another.


In general, you have to “guess” correctly some asked parameters of face-down cards:

  • Guess correctly the color of suit (red or black) of the next card in a deck. In case you were lucky your winning will get doubled because there are only 2 possible outcomes and your chances are a little bit less than 50 %, hence the winning only gets doubled.

  • Guess correctly the suit (hearts, diamonds, spades and clubs) of the next card in a cards deck. In this case, since there are 4 suits and chances to pick the right one are twice less than in case with guessing the suit’s color, your winning will be quadrupled. Fair enough, because chances of success are a little bit less than 25 % in this case.

  • The one card will be shown to you (face up, so you know its value at the beginning, for example, “J” ). Then you are going to be provided with 4-5 faced down cards to pick only one. If your card value is higher than slot’s card, then you win and vice versa. In the case if both cards end up to be the same value then it is counted as a draw; nobody wins or loses in this scenario.

Why it does not affect your chances of winning in online slot?

All casino games are designed in order to have an advantage for the “house” in the long run, and online casino slots are no exception.

Therefore, whether you only spin the reels or enjoy other online slot features as well, it does not make any difference in terms of payouts (RTP or House edge). The game causes losses for casino player in the long run anyway.

When you are trying to guess color of the suit, mathematically, chances to guess it right is 50%, but not in case with the double-up feature. If the odds were 50%, then this feature would not make any sense for software producer to integrate, because in the long race casino would not make any money and would only take risks that player hit a win big.

Considering online slot as a programming algorithm, it is in full control of all faced-down card’s values. It can show you whatever it would like to show, and it decreases your probability to win to around 47% (certain numbers depend on the particular online slot).

The same rule applies to “guessing the suit” feature. In this case, our probability to guess right becomes approx. 23,5%, instead of 25%.

Certain numbers are not getting disclosed by software providers. And be sure that they are lower than they would be in “real” life (50% and 25%). It is not a scam since nobody claims that online slots are profitable in the long run. The real-life probabilities are adjusted in online slots with a double-up feature to better meet the business goals of gambling operators.

The last think I would like to stress out, outcomes of Double-up round are based on RNG so that they are random and unpredictable.

When the Double-up feature could be harmful to online casino players?

Well, as we have already figured out, whether you use or not the double-up feature, the RTP of online slot stays the same.

Volatility level is another main parameter of video slot and under certain circumstances it could get affected by double-up feature in a huge way.

Let’s go through these two examples for a better understanding:

1) You are betting 1 euro per spin and hit the winning of the same amount (your whole balance, let’s say, is around 30 euro). In this situation, you are risking only this 1 euro if you choose to “double-up”. Nothing changes for you in terms of volatility. Whether you were lucky or not, it doesn’t impact your balance too much.

2) The situation is the same as the previous one, but now you were lucky and hit 200 euro winning instead of 1 euro. Here, if you prefer to double-up, you are risking this 200 euro. I would say, it is the same if you were betting 200 euro per spin. You are risking 200 euro per one click and if you do so, especially on a regular basis, then the volatility of online slot increases dramatically.

In conclusion

As for me personally, I use the double-up feature from time to time (rather rarely, because of the limited quantity of online slots with this feature on the market). If I do so, mainly because I want to make the gaming process more diverse and not because I think I can gain something (though, fair to notice, I will not lose extra money as well).

Watch out for some shady individuals claiming they found the Holy Grail how to profit from playing at online casino slots. And fiddling with online slots features doesn’t change the fact that the game was designed to be profitable only for online casino in the long run.