I played a 250/500 no-limit Hold'em cash game at Pokerstars and noticed the following:
If no one has raised yet, the preflop pot size is P = 750 (BB + SB). There is a
pot button, clicking
raise buttons adds (1000 + P) into the pot. If there were 750 chips in the pot, I would add 1750 more. The pot would now be of size 2500 and others would need to add up to 1750 to call.
However, if I click the
raise buttons, I am only adding 1500 into the pot.
Question: What is this extra 1000 for?