Rule 62 - Raise Requirements

62.1

The minimum raise required must always be equal to or larger than the amount of the previous bet or raise on that betting round, unless a player has moved 'all-in' for less.

62.2

If a player puts in a raise of fifty percent (50%) or more of the previous bet, but less than the minimum raise required, he or she will be required to make a full raise. The full raise amount required to complete the action will be the amount of the minimum raise required.

In NO-LIMIT, the first minimum raise requirement, after the flop, must be at least double the big blind amount. Additional raises may be in increments equal to or more than the previous raised amount.
In NO-LIMIT and POT-LIMIT, an 'all-in' bet of less than a full raise does not reopen the betting to a player who has already acted. There is NO cap on the number of raises in no-limit and pot-limit games.
In LIMIT betting structured games, the maximum number of raises will be 1 bet and 3 raises, until 'heads up' play; in certain situations, a venue’s house limit will apply. If the player raises 'all-in' for LESS, a raise must be at least half of the limit to constitute a raise.