How Large is the Minimum Raise?
For this example, lets assume the blinds are 50/100 in a no limit game.
Player 1 who is first to act after the big blinds (pre flop) raises to 300 Players 2 and 3 fold to player 4, who then places a chip in worth 500
Player 1 (whom we will call Jason) argued that you cant reraise someone less than double his original bet, in other words player 4 (whom we will refer to as Wood) could only raise a minimum now of 300, so therefore the minimum chips he could place in the pot in the form of a raise is 600.
Is this correct, I assumed that a re-raise was only limited to the minimum of the big blind, so that if someone bet 300, someone could make it 350, or, does the minimum raise then need to be double the previous bet? And does this change at all during betting rounds (pre flop - flop).
It is correct that you have to at least double the previous bet in no-limit Texas Holdem when you make a raise. The least you can bet is the same amount as the big blind.
Let's take a closer look at your example. Player 1 (Jason) raises to 300. With 100 blinds this means that the actual raise is 200. The minimum that player 4 (Wood) could raise to is therefore 500 (300+200).
The rules are the same for all betting rounds. But in each new betting round the minimum bet is always goes back to the same size as the big blind.
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