"Deposit £100, get £100 free." It sounds like free money. Whether it is depends almost entirely on one line in the small print: the wagering requirement.
What a wagering requirement is
A wagering requirement says how much you have to bet before you can withdraw a bonus, or any winnings made with it. A £100 bonus with a 35x requirement means you have to place £3,500 of bets first. Some offers apply the multiple to your deposit plus the bonus, which doubles it: £7,000 of bets for the same £100.
Why that matters: every bet costs the house edge
You don't lose the whole £3,500, of course. But every bet carries the house edge, so the more you have to bet, the more you're expected to lose along the way. On a slot with 96% RTP, the casino keeps about 4% of everything you bet on average:
- £100 bonus, 35x wagering: £3,500 of bets × 4% = an expected loss of £140. The bonus is worth about −£40: on average you finish worse off than if you'd never taken it.
- £100 bonus, 10x wagering: £1,000 of bets × 4% = an expected loss of £40. On average the bonus is worth about £60.
The quick formula: bonus − (amount you must bet × house edge). If the answer is below zero, the bonus costs more than it gives on average.
What the average hides
Averages hide how this usually plays out. Many players lose the bonus long before they finish the wagering and never see a penny of it. A few hit a big win and cash out more. And the requirement itself does something the maths doesn't show: it keeps you playing. £3,500 of slot spins at £1 each is around nine hours of play at a typical online pace.
The UK now caps it at 10x
From 19 January 2026, the UK Gambling Commission banned wagering requirements above 10 times the bonus for gambling businesses licensed in Great Britain. The Commission's reasoning was that high requirements can intensify gambling and make offers confusing. Outside Great Britain, much higher requirements are still allowed in many places, so it's worth doing the calculation yourself.
Before you take any bonus, check
- The multiple, and whether it applies to the bonus alone or to your deposit plus the bonus.
- Which games count. Many offers count only slots, or count table games at a fraction.
- The deadline and the maximum bet allowed while the bonus is active.
- Any cap on winnings you can withdraw from the bonus.
To see what the betting you'd need to do costs at a given RTP, put the numbers into the calculator, or read what RTP really means.
Sources
- UK Gambling Commission: Socially responsible incentives: maximum of 10 times wagering requirements from 19 January 2026
- Wizard of Odds: House edge of casino games compared