Your rollover contribution is determined once your bets are settled and is based on how those wagers performed. 

The formula is simple:
Rollover = (Deposit + Bonus) x Rollover Multiplier 

This total will be clearly shown when you make a deposit and claim a bonus. 

Example:
If you deposit $100 and receive a $25 bonus with a 6x rollover, your required wagering amount will be:
($100 + $25) x 6 = $750
You must place $750 in total bets before you’re eligible to make a withdrawal.