In relation to no deposit bonuses specifically, a limit will be applied on how much you can withdraw after converting the bonus into real money. This is another precautionary measure imposed by the casino so they don’t pay out excessive winnings to multiple players.
As to what limit will be applied depends on the casino itself. As a general guide, you can expect something from between R10 up to R100, although some of the more generous offers listed on NoDepositKings can stretch much higher.
If you feel withdrawal limits are slightly unfair, especially after you fulfil some pretty high wagering requirements, then a perfect solution is to claim a match deposit bonus instead. They’ll either increase the withdrawal limit or remove it altogether, allowing you to keep everything you win!