What is a House Edge?

What is a House Edge?

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What advantage does the online casino have over the player?


Online casino games have an advantage to the casino (often referred to as the ‘house’) built into their game design.

With online casino games, the house edge varies greatly with the game.

Bingo and keno for example can have house edges up to 25-30%, online slot machines will typically have less than 5%, european roulette less than 3% and blackjack less than 2%.

In games that have a decision making element such as blackjack, the house edge is calculated using the advantage when optimal play or basic strategy is used.

For a more detailed explanation of how to use blackjack betting strategies to improve your odds of winning when playing see: Blackjack Strategy & Betting Systems

In games like poker and bingo where players are competing against each other rather than the house, the casino will earn money by taking a commission for providing the game.

This commission is more commonly known as a ‘rake’.



Does the house always win?

The house advantage works over long-term gameplay. It is based on the average payout over many millions of individual bets.

This means that in the short term players have the possibility to win and in some cases, these wins can be very large.

For tips and strategies to improve your chances when playing slots online see our guide: How To Win At Online Slots



What is an edge in gambling?

Where a casino game has a skill element and player decisions can influence the win or lose outcome – players with understanding, experience and skill can in some circumstances remove the long-term disadvantage (house edge).

People that play, bet or gamble on sports or casino games with an edge like this are called advantage players.



House edge meaning

Based on the above, we now know that if you play many rounds, bets, hands or spins of online casino games that the mathematical advantage of the games favours the casino, giving them their house edge.

For the casino site, the advantage gives them the comfort that even though some players are winning in the short-term, over the longer term they can be confident that they will profit overall.



How do you find house edge?

Starburst Game Play Screenshot
Starburst Slot Game – Click the ? to open the Help information


Every UKGC licensed casino site must make the payout rate on each game available to players.

It is the same process at all casino sites, whether you play at Sun VegasVideoslotsMansion Casino or anywhere else, for players to find the game payout rate.

  1. Launch the game that you want to check
  2. Click the Help or ? icon
  3. Scroll down through the game information text to find the ‘RTP’

RTP is the ‘Return-to-Player’ percentage.


How to calculate the house edge

Once you have found the RTP number for the game, subtract this from 100 to calculate the house edge.

The lower the number you are left with, the lower the house edge.

Here is an example:

One of the most popular online slot games is Starburst.

We can easily find the RTP using the instructions above.

On BGO we can see that it is 95.05%

Starburst at BGO Online Casino
Starburst at BGO Online Casino


100 minus 95.05 = 4.95

The house advantage to BGO when we play Starburst is 4.95%

Or put another way, for every £100 that is bet on Starburst at BGO, the casino is making around £4.95.



What is the house edge in blackjack?

Blackjack at Sun Bingo
Blackjack at Sun Bingo


First, we need to consider – how does the house have an edge in blackjack?

The advantage for the casino in blackjack is because the player has to decide first and if they bust then the player automatically losses.

This is regardless of whether the dealer hits then busts in the same game round. If there are no other players, the dealer doesnt even need to play their hand.

For those of us that want to understand house edge before playing, blackjack is an attractive game to select.

House edge is relatively low in blackjack compared to other online casino games.

An inexperienced or undisciplined player will experience around 2% house edge. By using a basic blackjack strategy this can be reduced to the advertised in-game RTP, often below 1%.


Is blackjack skill or luck?

The house edge in blackjack is from the dealer having a hidden card.

A player has to make assumptions about what the dealers hidden card could be.

When a player busts, the dealer wins – even if the dealer busts in the same game round.

With these elements of the game in mind, winning at blackjack is about luck as you need to be dealt the best cards.

However, learning and understanding blackjack true odds and strategy can reduce the disadvantages that the player has. The player can reduce the house edge by developing and using skill when they play.

When playing with real money online, you can keep the perfect strategy open and refer to it before making any decisions.

Eventually, you may even become so familiar with the betting strategy that you memorise how to play each scenario.



What is the house edge in roulette?

European Roulette at Fabulous Bingo
European Roulette at Fabulous Bingo


When considering the house edge advantage with roulette we first need to understand the difference between European and American roulette.

The European roulette wheel has 37 numbered slots, from 0 to 36.

In the American roulette version, there is an additional 00 number on the wheel and there are therefore 38 numbered slots.

Both versions however have the same payout amount when the ball lands on the number that you have bet on, which is 35:1.

For every £1 that you bet on you are paid a profit of £35, so £36 is paid to you in total.

The additional 00 number on the wheel in American roulette gives a house edge of just over 5% vs a European roulette house edge of just over 2%.

It is therefore recommended that where the option is available, always select European roulette rather than American.



What is the house edge on slots online?

At UKGC licensed online casinos the slot games are typically around 95% RTP, or 5% house edge advantage.

This varies per game and even per casino.

Each casino can offer a slightly different RTP version of the same game, so always check before playing.

Follow the guide above to check the RTP.

Here are some of the most popular online slot machine games amongst UK players and their typical RTP / house edge. Remember to check each game at each casino you play with as they can offer different versions.


Online Slot GameRTPHouse EdgeAvailable at
Fluffy Favourites95.388%4.612%Sun Bingo
Rainbow Riches95%5%Sun Vegas
Starburst96.09%3.91%Mansion Casino
Cleopatra95.02%4.98%Fabulous Bingo
Book of Dead96.02%3.98%PlayOJO


Selecting and playing only the highest RTP is one of the best ways to pick slots at an online casino.

The RTP of jackpot slot games is lower. This is because a percentage of your bet is taken and added to the pot. Jackpots are one of the highest house edge games for an online casino.

RTP of video slot games online is consistent no matter what time of the day you are playing or who else is winning. So you don’t need to consider what the best time to win on slot machines is or if a game is ‘hot’ or ‘cold’.



At Casino Sites Online we work to provide you with everything you need to know for playing at online casinos.

For lists of where to play see our category pages:

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