House edge meaning, simply: it is the average percentage of every stake that a casino game keeps for the operator over the long run. A slot with a 4% house edge keeps about 4p of every £1 wagered on average, which is the same as saying its RTP is 96%. It is the built-in cost of playing, and no bonus removes it.
House edge = 100% minus RTP, so a 96% RTP slot has a 4% edge.
Expected cost of play ≈ total amount staked × house edge.
£1,000 of wagering at a 4% edge costs about £40 on average.
Faster play means more stakes per hour, so a bigger total cost.
Bonuses don't change the edge; they only add value to set against it.
Formula
100% − RTP
Cost of play
Amount staked × edge
Example
£500 wagered at 4% ≈ £20
Single-zero roulette
2.70% (1 in 37)
Changed by a bonus?
No
House edge meaning and how it is calculated
Every casino game pays out slightly less than the true odds of winning. The difference is the house edge. On a slot, it comes from the gap between what the pay table pays and how often each combination lands. On a table game, it usually comes from a single extra outcome, such as the green zero in roulette. Either way, the result is the same: for every pound staked, the game is designed to keep a small slice on average.
House edge and RTP are two ways of describing one number. A game with 96.21% RTP, like Book of Dead, has a 3.79% edge. A game with 98.00% RTP, like Blood Suckers, has a 2% edge. The edge is the clearer number to think about when you want to know what play costs, and it appears again and again in our casino bonus glossary.
Where the house edge comes from: a roulette example
Single-zero roulette has 37 pockets: 1 to 36 plus zero. A straight bet on one number pays 35 to 1. If the true odds were respected it would pay 36 to 1, because there are 36 losing pockets for every winning one. Bet £1 on each of the 37 numbers and you stake £37, but the winner returns only £36 (your £1 plus £35). That £1 shortfall out of £37 is a 2.70% edge, and it applies to almost every bet on the table.
Wizard of Odds publishes edges for every roulette and blackjack (opens in a new tab) variant; blackjack's edge depends heavily on the table rules and the player's decisions. Its roulette guide (opens in a new tab) shows how double-zero wheels nearly double the edge. Table games often count for little or nothing towards bonus wagering, as our table games bonus page explains.
House edge and the real cost of wagering requirements
When a bonus has wagering requirements, you have to stake a set amount before bonus winnings can be withdrawn. The house edge tells you what that staking costs on average. The table uses our partner deposit-match offers at three edges.
Average cost of clearing wagering at different house edges
Bonus and wagering
Total to wager
Cost at 2%
Cost at 4%
Cost at 6%
Casumo £10 bonus (£20 deposit), 10x
£100
£2
£4
£6
10bet £25 bonus, 10x
£250
£5
£10
£15
Casumo £100 bonus (£200 deposit), 10x
£1,000
£20
£40
£60
Pre-2026 style £100 bonus at 35x
£3,500
£70
£140
£210
The last row shows why the 10x wagering cap matters. Since 19 January 2026, LCCP social responsibility code 5.1.1 (opens in a new tab) has limited wagering to 10 times the bonus: at 35x and a 4% edge, the average cost of wagering a £100 bonus was larger than the bonus itself. At 10x it is well under half. These are averages; any one attempt can end with the balance gone long before the wagering is complete, or with much more than expected. Our wagering calculator runs the same sums for any offer.
House edge per hour: why speed and stake matter
The edge is a percentage of what you stake, so the more you stake in a session, the more it costs on average. Two things drive that: stake size and the number of rounds. UK online slots must take at least 2.5 seconds per spin, and other online casino games at least 5 seconds per round since 17 January 2025, which limits the pace but still allows hundreds of rounds an hour.
Worked example: 300 spins in an hour at 20p is £60 staked. At a 4% edge the average cost is £2.40 for that hour. Raise the stake to £1 and it becomes £12. Lowering your stake or taking breaks reduces the expected cost; a different game choice changes it only a little. The session entry covers the time tools that help.
How the house edge shows up in bonus terms
You won't find the phrase in most offer terms, but several clauses exist because of it:
Game weighting. Low-edge games like blackjack often count at a reduced rate or not at all; see game weighting.
Excluded games. Some slots with very high RTP are left off bonus play lists. The offer's selected games list is the only one that counts.
Max bet rules. Casumo caps bets at £5 while a bonus is active, which limits how fast both the edge and the wagering work through.
Max win caps. 10bet limits bonus winnings to £1,000, which trims the upside the edge has to be set against.
None of these is a reason to try to dodge the rules; breaking play restrictions can void winnings. They are simply the casino managing its edge.
House edge myths and facts
Myth: a betting system can beat the edge. Doubling up or changing stake sizes doesn't change the percentage on each bet.
Myth: bonus money has no edge. Every stake, whoever funds it, carries the same edge.
Fact: the edge works on turnover, not deposits. Re-staking the same £10 many times means the edge applies each time; see turnover.
Fact: short sessions vary wildly. You can be ahead after a night; the edge shows itself over many rounds.
Our expected value entry shows how the edge and a bonus combine into one average figure.
House edge and our partners' no-wagering spins
No-wagering free spins sidestep the wagering cost in the table above, because winnings are paid as cash. Coral gives 100 free spins (10p each) once you deposit and bet £10 on slots; Ladbrokes gives up to 500 (50 a day for 10 days, 10p each) after a £10 slots spend; PlayOJO gives 80 spins on Big Bass Bonanza (10p each) on a first deposit of £10 or more. The qualifying £10 bet still carries the slot's edge, about 40p at 96% RTP, and payment exclusions apply at Coral and Ladbrokes. All are 18+, new customers only, with full terms on each free spins no wagering offer page.
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: set a budget. Free, confidential help: National Gambling Helpline 0808 8020 133.
Frequently asked questions
What does house edge mean in a casino?
House edge is the average share of each stake a casino game keeps for the operator over a long run of play. If a game has a 4% house edge, it keeps about 4p of every £1 wagered on average and pays back the other 96p, its RTP. The edge is built into the pay table, so it applies to every bet. Your own results will vary a lot in the short term. See RTP for the same number seen from the player's side.
How do you calculate house edge from RTP?
Subtract the RTP from 100%. A slot with 96.71% RTP, such as Big Bass Bonanza, has a 3.29% edge; Starburst at 96.09% has a 3.91% edge. To turn that into pounds, multiply by what you stake: £200 of spins at a 3.91% edge costs about £7.82 on average. Use the RTP shown in the game's help screen, since some slots come in several versions. Our high RTP slots for bonuses guide lists published figures.
How much does it cost to clear a casino bonus?
Roughly the total wagering multiplied by the house edge. A £50 bonus at 10x needs £500 of wagering, which at a 4% edge costs about £20 on average. Casumo's full £100 bonus at 10x means £1,000 of play, so about £40 at 4%. Your real result could be much better or worse, and many attempts end before the wagering is finished. Our guide on how to calculate wagering requirements shows each step.
Does a casino bonus remove the house edge?
No. A bonus adds value to your account, but every stake you place, whether from cash or bonus funds, still carries the game's edge. Over enough play the edge wins out, which is why gambling should be treated as entertainment that costs money. A bonus can offset part of that cost, but it doesn't make gambling cheaper or safer overall. Read is gambling with a bonus safer? for the full answer.
Which casino games have the lowest house edge?
Some table games, such as blackjack under favourable rules, have lower edges than most slots, and single-zero roulette sits at 2.70%. Among slots, a few publish RTPs near 98%, a 2% edge. But low-edge games are often weighted down or excluded from bonus wagering, so they may not help with an offer at all. Check the terms before you play. Our page on which games are excluded from bonuses explains the usual rules.
Can you beat the house edge?
Not over the long run with standard casino games. The edge is part of every bet, and no staking pattern, timing or system changes it. You can have winning sessions, sometimes large ones, but the average result across many rounds is a loss equal to the edge times what you staked. Treat any claim of a system with suspicion. Our bonus myths guide covers the most common ones, and support is on our safer gambling page if play feels hard to control.
Is the house edge the same as the casino's profit?
Not exactly. The house edge is the theoretical margin on each stake; the casino's actual takings, called gross gambling yield, are stakes minus winnings paid out, before costs, taxes and the cost of bonuses. In any given month an operator's real margin on a game can be above or below the edge. Since 1 April 2026 online operators pay remote gaming duty at 40% of their gaming profits. See remote gaming duty for the detail.
Why do free spins still carry a house edge?
Because each free spin is played on a normal slot with its normal maths. 100 spins at 10p have a face value of £10, and at 96% RTP they return about £9.60 on average: the missing 40p is the edge. You aren't paying for the spins with your own money, but the qualifying bet usually is your money and has the same edge. Read are free spins really free? for how the conditions work.
Gambling can be addictive. Free, confidential help is available 24 hours a day from the National Gambling Helpline on 0808 8020 133. Visit GamCare.org.uk and GamCare, or block yourself from all UK-licensed gambling sites with GAMSTOP.
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