The minimum bet is the size of the biggest blind. The amount of a blind depends on the limit of a game.
The blind is simply the first bet so keep in mind the rules for the blind bet when it comes to calculating a minimum bet size are the same as any other bet that might be made.
A second bet, called a raise follows the same rule, the minimum size of the raise is always the size of a bet made.
The maximum size of a bet or raise, is whatever amount the player making the bet or raise has in their stacks to bet with.
In poker vernacular a bet and a raise are two different things, but they are the same thing, in the sense that what the minimum raise is, is predicated on what happened before. If nothing happened, there was no bet, the minimum of the bet is the amount of the blind. If their was a bet, the minimum raise is the size of that last bet.
The minimum size raise is not a aggregate of the sum of the previous action. If a player bets 1, player B then raises to two, the minimum raise is still one. I will give you some examples a little further down in the post.
In any poker game their may be two or more rounds of betting. A round is when the action goes around the table, and each player acts on their hand, Than more cards or seen and another round goes around. What happens on a round does not affect the minimum bet size. The minimum bet size resets to the size of the big blind at the beginning of each round.
In Hold em, The first round is when your given two cards. Next round is when a flop of three cards is put out, than next round is when the fourth card (the turn) is put out, and last round is when the fifth card (the River) is put out. The minimum bet size is the same at the start of each of these rounds, starts at whatever the blind is.
Some examples of the pattern:
Bet is one minimum raise is one.
If the bet is one, a player raises to 3, The raise is two, 1 is a call and two is a bet. When someone raises they are technically calling and making a bet. When a player makes it three he is betting two and calling a one dollar bet. At this point the minimum raise is two.
If someone bets 50, and then some one makes it 200, the raise is 150. The raising player is calling 50 and raising 150. The minimum raise then becomes 150.
When determining what the size of a raise is, you first subtract the amount of the call. Just to be clear, a call is when someone matches a bet. if a bet is one, you match the bet with one, that is a call.
Whenever a raise is made, the player making the raise is calling and betting. You need to consider that when your figuring out what the actual raise is.
Think and terms of call and bet, instead of raise. A raise is a call with another bet on top of it. This bet on top of a call, is at a minimum the last bet, and if the bet is more then the call, it becomes the new minimum for the bet on top of a call.
If the action goes, Player A makes it 10, Player B makes it 50, Player C makes it 100, Then player A Makes it 250 When it gets back to her, the following is what has happened with the minimum raise bet size at each step of this action.
Player A has called the blind and bet an amount over the blind. If the blind was 1 his call was one and his bet was 9. If the blind was 5, his call was five and his bet was five. We will use the later, say the blind was five his raise was five, the minimum bet did not change.
Player B has a minimum raise amount of 5. If he was not to make another bet, his call would be ten. Since he made it 50, the call minus his bet, is 40, which is the new minimum bet at this point. 40 being the amount he bet over the call.
Next Player C puts in 100, The minimum raise is now 50. His call was 50, and he bet another 50 on top of that, the amount over the call he bet is the new minimum, of 50. The amount the next player must call before raising, the over bet is now 100.
Back to player A and he makes it 250, He has called 100, and made another bet of 150 more to come up with 250. The new Minimum raise is now 150.
Test question for OP:
Player A with a call and minimum raise could of made it as little as ____, when the action got back to him?
On bad TV shows they sometimes say "I will call you and raise you" in the fictional poker game. And this is an absolutely correct way to describe the mechanics of a raise. In a real world poker game, if you intend to call and say call you cannot proceed with a raise. When someone makes a raise they don't call it a bet they call it a raise.
If you want to put it down to code, A raise is a bet, over the amount of a call, two separate pieces of data that need to be calculated against each other to come up with the amount of the minimum raise at any particular point in the game. What a normal bet has in common with a raise bet, they are the bets that hold the value of the minimum raise. If I was naming the variable I would call it LastBetAmount, since the last bet amount is the minimum raise.