What a casino bonus is really worth

A 100 percent match sounds like doubling your money. Once you put the wagering requirement and the house edge into the same sentence, the real number is a lot smaller — and still sometimes worth taking.

Bonus marketing is built on a single trick of framing: the headline is the amount you receive, and the conditions are the amount you have to do. Both are printed, but only one is in large type. Putting them side by side takes about a minute and changes which offers look attractive.

The three numbers that matter

Ignore the percentage for a moment. An offer is defined by the wagering multiple, the maximum bet permitted while wagering, and the expiry window. Everything else is decoration.

• Wagering multiple. A bonus of 100 at 30x needs 3,000 in total stakes before anything converts. That is turnover, not losses — but it is turnover you have committed to.
• Maximum bet while wagering. Often a small fixed figure. Breach it once, even by accident on a single spin, and the bonus and everything won from it can be removed.
• Expiry. Seven to thirty days is typical. Wagering not finished in time is wagering done for nothing.

Putting a number on it

Take a 100 bonus at 30x on slots with an average return of 96 percent. You have to stake 3,000. The house keeps roughly four percent of that on average, which is 120. So the expected cost of clearing the bonus is slightly more than the bonus itself.

That sounds damning, and it is the reason bonuses exist. But it is an average across a huge number of spins, and you will play a few hundred. The distribution is wide enough that plenty of people finish ahead. What the arithmetic tells you is not that bonuses are traps — it is that they are close to neutral, so the conditions decide everything.

Game weighting, the quiet clause

Slots usually contribute 100 percent towards wagering. Roulette often contributes 10 percent or less, and live blackjack sometimes nothing at all. If you claim a bonus and then play the games you actually enjoy, you can stake thousands and clear almost none of the requirement.

When a bonus is genuinely worth taking

1. The multiple is low, in the region of 20x to 30x rather than 40x and above.
2. You mainly play the games that contribute fully.
3. The maximum bet limit is one you would stake anyway.
4. The expiry gives you enough sessions to finish without rushing.
5. You would have deposited that amount regardless of the offer.

If the last point is not true, the offer has changed your behaviour rather than rewarded it, which is precisely what it was designed to do.

Declining a bonus is always allowed, and for anyone who plans to withdraw at short notice it is usually the better choice.