When you eagerly claim a massive casino bonus, the required playthrough or wagering requirement is usually heavily advertised.

Because different games have vastly different house edges, the casino assigns a specific "contribution percentage" to each game category.
Slot Machines: The 100% Contribution Standard
In almost every single online casino, standard video slot machines contribute exactly 100% toward your wagering requirements.

Because the mathematical edge favors the house so heavily, the casino is confident they will slowly drain your balance.
Always read the "restricted games list" before spinning with bonus fundsClassic 3-reel slots sometimes have a lower contribution rate than modern video slotsProgressive jackpot slots are almost universally excluded from bonus play entirely The Mathematical Penalty on Skill Games
Because these games feature an incredibly low house edge (often under 1%), casinos heavily penalize them regarding bonus contributions.

Many modern online casinos take this a step further and simply reduce the table game contribution rate to absolute zero.
Protecting Your Bonus Funds
Before you ever deposit money to claim an offer, you must relentlessly hunt down the casino's specific bonus Terms and Conditions.

If you exclusively play live dealer roulette, accepting a bonus where roulette contributes 0% is a massive, incredibly frustrating mistake.
Game CategoryTypical Contribution %Speed of ClearingVideo Slots100%Very FastBlackjack5% - 10%Agonizingly Slow
Wagering contributions are the casino's mathematical safety net, carefully designed to protect them from skilled table game players.