The size of your bets is all relevant to the slot game that you want to play and, usually, the rule of thumb is that the larger the number of paylines, the larger the bet size will potentially be. It all comes down to the casino though and how willing they are to extend the range of the lower and upper limits of each slot game. The maximum bet button is a quick way to find out the biggest bet limit and more often than not, your minimum bet will be anywhere between $0.01 to $0.20 per spin.