A 200% welcome bonus sounds incredible - until you read the 40× wagering requirement buried in the terms. Here's how to calculate real bonus value in under 2 minutes.
Casino bonuses are the most misunderstood part of online gambling. The headline number - "500% up to £5,000!" - is designed to impress, not inform. The actual value of any bonus is determined almost entirely by the wagering requirement attached to it.
What Is a Wagering Requirement?
A wagering requirement tells you how many times you must bet the bonus amount (or sometimes the bonus plus deposit) before you can withdraw any winnings derived from it. A 40× wagering requirement on a £100 bonus means you must place £4,000 in total bets before the bonus converts to withdrawable cash.
The Real-Value Formula
Here's how to compare bonuses accurately:
Real value = Bonus amount × (1 − House edge × Wagering requirement)
For a typical slot machine with a 4% house edge and a 40× wagering requirement on a £100 bonus:
£100 × (1 − 0.04 × 40) = £100 × (1 − 1.6) = negative expected value
This means statistically, you'll lose more than you gain from the bonus itself. This doesn't mean you should never take bonuses - but it does mean you should be realistic about what they actually offer.
What Makes a Good Bonus?
- Wagering requirement under 30× - anything above 40× is very hard to beat mathematically
- Slots contribute 100%, table games contribute more than 0% - many bonuses exclude table games entirely
- No maximum cashout limit - a £50 max cashout on a £200 bonus kills the upside
- Reasonable time limit - 30+ days to complete wagering is fair; 7 days is very tight
- Low minimum deposit - you shouldn't need to deposit £100 to claim a £20 bonus
No-Deposit Bonuses: The Exception
No-deposit bonuses are typically small (£5–£20 in free credits or spins), with high wagering requirements (50×+). But because you're risking no money of your own, even a small expected value is positive. Claim them if they're available - just don't count on winning.
The Bottom Line
Before claiming any bonus, ask: what is the wagering requirement, which games count towards clearing it, is there a maximum cashout, and how long do I have? If the casino makes these terms hard to find, that's itself a red flag worth noting.
