Kelly criterion for stake sizing
We use the Kelly criterion for deciding the optimal stake when betting on value bets.
The Kelly criterion calculates the optimal stake for maximum growth of your bankroll, proportional to the perceived value of the bet.
However, most sports traders will bet a fraction of the suggested Kelly stake size, to handle the uncertainty of constantly changing odds. Using 100% of Kelly leads to higher variance and steeper draw-downs. Lowering the Kelly stake sizing, together with having a set max bet size, is a good way to manage this risk.
30% is the default setting in ValueBetting. You can change this by going to Options / User in ValueBetting. But before you do, that please make sure you have understood how your Kelly stake sizing affects variance.
Also remember to update your bankroll often.