Casino Bonus EV Calculator
Most bonus calculators tell you how much you have to stake. This one tells you what the offer is worth: the expected value of taking it, after the house edge has been paid on every pound of that turnover, and after a maximum withdrawal cap has been applied to whatever is left. A wagering requirement is a price. This works out whether the bonus is worth the price.
The offer
RTP is the return to player of the game you intend to clear the bonus on, so the house edge is 100% minus that figure. Contribution is the share of each pound staked that counts towards the requirement — 100% on most slots, often 10% or 20% on table games, and sometimes 0%, which makes clearing impossible rather than slow.
What the bonus is worth
- Effective requirement (W ÷ contribution)
- 35.0×
- Total turnover required
- £3,500.00
- House edge on that turnover
- £140.00
- Bonus credited
- £100.00
- EV before any cap
- −£40.00
- Break-even requirement
- 25.0×
- Spins at your max bet
- 700
At this game and this contribution, the offer turns negative above 25.0× and you have been quoted 35.0×.
The one identity worth memorising: only W ÷ contribution exists
Every bonus is advertised by its multiplier — 35×, 40×, 20× — as if the number were comparable between offers. It is not, and the reason is arithmetic rather than opinion. To clear a requirement of W times a base of size b on a game contributing a fraction c of each stake, you must stake W × b ÷ c. The house edge h is charged on all of it. So the expected value of the whole exercise is:
EV = B − h × (W ÷ c) × b
B is the bonus credited, h is the house edge (1 − RTP), W is the quoted multiplier, c is the game contribution, and b is whatever the requirement is applied to — the bonus alone, or the deposit plus the bonus.
W and c never appear separately. They appear only as the ratio W ÷ c, which means a 35× requirement on slots contributing 100% and a 7× requirement on a table game contributing 20% are the same requirement, priced identically, however differently they read in the terms. The friendlier-looking number is the one attached to the lower contribution, and it is friendlier by exactly nothing. This is also why a 0% contribution is not a slow route but a closed one: divide by zero and the turnover is infinite.
Set EV to zero and the break-even multiplier falls out. On a bonus-only requirement, where b = B, the bonus cancels entirely and the answer depends on nothing but the game: W* = c ÷ h. At 96% RTP and full contribution that is 25×, and it does not matter whether the bonus is £10 or £1,000. Our deposit-plus-bonus versus bonus-only guide covers what changes when b is the larger base: a 100% match becomes twice as demanding, and the break-even multiplier halves to 12.5× on the same game.
Break-even requirement by game and contribution
The quoted multiplier at which a bonus-only offer is worth exactly nothing. Above the figure in the table the offer costs you money in expectation; below it, it pays. Read down the column that matches the contribution in the terms, not the one that matches the game you had in mind.
| Game RTP | House edge | 100% contribution | 20% contribution | 10% contribution |
|---|---|---|---|---|
| 92% | 8.0% | 12.5× | 2.5× | 1.3× |
| 94% | 6.0% | 16.7× | 3.3× | 1.7× |
| 95% | 5.0% | 20.0× | 4.0× | 2.0× |
| 96% | 4.0% | 25.0× | 5.0× | 2.5× |
| 97% | 3.0% | 33.3× | 6.7× | 3.3× |
| 98% | 2.0% | 50.0× | 10.0× | 5.0× |
The column that surprises people is the one on the right. A 3× requirement on a game contributing 10% sounds generous and is worse than 25× on slots, because the turnover it demands is thirty times the base rather than three. Contribution is covered in full in our game contribution guide.
What a withdrawal cap really does to the number
A maximum withdrawal cap of M does not reduce the expected value by some proportion. It puts a hard lid on the outcome, and the consequence for the expected value follows from a standard inequality: the average of a capped quantity can never exceed the cap, and can never exceed the uncapped average either. In this setting that gives an exact ceiling, and the calculator applies it above:
EV ≤ min( B − h × (W ÷ c) × b , M − D )
M is the maximum you may withdraw and D is your own deposit, which you had before the offer existed.
Two things follow immediately, and neither is usually stated. First, if M is less than or equal to your deposit, the offer cannot make you money at all: the best outcome permitted by the terms is to withdraw less than you put in. That is a complete answer, obtained without knowing the game, the multiplier or the contribution. Second, a cap only bites from above, so a capped bonus can be negative-EV while an identical uncapped one is positive — and no amount of choosing a better game will rescue it, because the ceiling is not a function of the game.
Worked example. Deposit £20, bonus £20, 10× on the bonus only, 97% RTP at full contribution: turnover £200, expected cost £6, so the uncapped EV is £14. Attach a £25 withdrawal cap and the ceiling becomes £25 − £20 = £5. The offer is still worth taking, but it is worth a third of what the wagering arithmetic alone suggested. The cap and its variants are set out in our maximum withdrawal cap guide.
A worked example end to end
Take the offer the calculator opens with, because it is the most common shape on the UK market: deposit £100, get £100, 35× wagering on the bonus, slots at 96% RTP contributing 100%, £5 maximum bet while the bonus is active.
- Turnover: 35 ÷ 1.00 × £100 = £3,500
- House edge paid: 4% × £3,500 = £140
- Expected value: £100 − £140 = −£40
- Break-even requirement: 1.00 ÷ 0.04 = 25×
- Spins to clear at £5: £3,500 ÷ £5 = 700
The offer is priced at ten multiples above its own break-even, and it costs £40 in expectation to accept. Move the same requirement to the deposit plus the bonus and the turnover doubles to £7,000, the cost doubles to £280, and the expected value falls to −£180 while the headline number in the advertisement does not change at all.
None of this says a bonus with negative expected value is irrational to take. It says what it costs, which is the thing the terms do not tell you. Seven hundred spins of entertainment for £40 is a purchase, and a defensible one; the same £40 spent believing the bonus was free is not. If you want the turnover and the cash cost without the expected-value layer, the wagering requirements calculator does that job, and casino bonus wagering explained covers the terms themselves.
Frequently asked questions
Does a positive expected value mean I will win?
No. Expected value is an average over many repetitions of the same offer, and a single bonus is one draw from a distribution that is heavily right-skewed on slots: the common outcome is losing the lot well before the wagering is cleared, offset by rare large wins. A positive figure says the offer is priced in your favour, not that this attempt will end well.
Why does the calculator ignore my chance of going bust?
Because busting is already inside the expected value. If the balance reaches zero the wagering stops and so does the house edge, and the arithmetic above charges the edge on the full turnover as though you always completed it. That makes this a conservative reading of a bad offer and a slightly pessimistic one of a good offer. What it does not capture is the variance — how far the outcome is likely to stray from its average — which is a property of the game rather than of the terms.
Where do I find the RTP and the contribution?
RTP is published in each game's own information panel, usually under rules or paytable, and is often different from the same game's RTP at another operator. Contribution is in the bonus terms rather than the game, normally as a table by game category, and it is the figure worth reading first because it multiplies the turnover.
Does the maximum bet rule change the expected value?
Not in itself — the edge is charged per pound staked, not per spin, so a smaller maximum bet changes how long clearing takes rather than what it costs. It matters for a different reason: breaching it is the most common way a bonus and its winnings are voided, at which point the expected value of the offer is not what this page calculated but the whole of your bonus balance. Our max bet rule guide sets out how the limit is applied.
18+ — Gambling should be entertainment and never a way to make money. A bonus with positive expected value is still a gamble on a single outcome. If it stops being fun, take a break: responsible gambling.