When a casino gives you a welcome bonus, you usually can't withdraw it right away: first you have to wager it (or wager the bonus plus your deposit, depending on the operator) a set number of times. That multiplier is the wagering requirement, usually shown as ×20, ×30, ×40, and so on. It's the most important condition of the bonus — more than the amount itself.
The bonus is calculated as B = min(deposit × percentage, max bonus). From there, the amount you need to wager is B × wagering requirement (if the rollover applies to the bonus only) or (B + deposit) × wagering requirement (if it applies to the bonus plus deposit). One variable that's easy to miss is game contribution: not every game counts the same — slots usually count 100%, while roulette and other table games usually count only a fraction (for example 10-20%), which can double or triple the real volume you need to bet.
| Deposit | K300 |
|---|---|
| Bonus amount (100%) | K300 |
| You need to wager (×40) | K12,000 |
| Expected loss (RTP 96%) | K480 |
| Bonus expected value | -K180 |
Compare the amount you need to wager with the statistically expected loss based on the RTP of the game you pick. If that expected loss is higher than the bonus itself, the bonus has a negative expected value: statistically it's not worth chasing for the bonus alone, even though it can still be a way to play longer with the same deposit.
Some operators calculate the rollover on the bonus amount alone; others calculate it on the bonus plus your original deposit. The difference is large: with a 100 deposit and a 100 bonus at ×40, wagering “bonus only” means a total volume of 4,000, while “bonus + deposit” pushes that up to 8,000. This condition is usually buried in the fine print of the bonus terms, not the promotional banner.
Beyond the wagering requirement and its calculation base, it's worth checking: the time limit to complete the rollover (some operators give only 7-14 days), which games are excluded or count at a reduced contribution, and whether there's a maximum withdrawal cap on winnings made with the bonus (some operators cap that withdrawal at a fixed multiple of the bonus, even if you won more).