Seeking solutions to some scenarios to understand raise and re-raise?

Question

I played four person pokerTH game many times on computer but failed to understand following scenarios.I hope understanding these will help me become a better player. Kindly clear my confusions if possible( The four players are SB , BB , Dealer and Player 1) (The formula for Raise appears to be= Previous Bet +Previous Bet – BB but it doesn’t seem to apply to all scenarios below) All scenarios are for the preflop round.

Scenario 1: I am playing Small Blind. I post small blind $10. Big Blind posts $20. Player 1 calls $20. Dealer calls $20. Next I can Fold , Call($10) , or Raise. My question is what should be my minimum raise and why ? (Computer says $30 )

Scenario 2: I am playing Dealer. SB posts $10. BB posts $20 . Player 1 bets $40. Next I can Fold , Call ($40),Raise. My question is what should be my minimum raise and why ? (Computer says $60)

Scenario 3: I am the Player One. SB posts $10.BB posts $20. Next I can Fold ,Call ($20) or Raise. My question is what should be my minimum raise and why ? (Computer says $40)

Scenario 4: I am playing Big Blind. SB posts $10. I play $20. Player 1 folds. Dealer calls $20. SB bets $30. Next I get the option to Fold , Call ($20) or Raise. My question is what should be my minimum raise and why ?(Computer says $40)

There are other posts explaining raise and re-raise but I could not understand them because examples were missing. Please solve the above examples. I am quite new to the game.

Answer 1

In all betting rounds, the minimum raise is the amount of the previous raise (or opening bet if there have been no previous raises). In the first round only, the big blind is considered the opening bet if it is equal to the game's minimum. If the big blind is smaller than the game minimum, the the opening bet is the first bet of at least the minimum.

So, scenario 1: $20 BB was the opening bet, so the minimum raise is another $20, making $40 total. Since you have $10 in the pot, you must add $30 more to raise.

2: Opening bet was $20, there was a raise of $20 more to $40, you must raise at least another $20, making it $60.

3: Essentially same as #1. You must raise to $40, but since you had no money already in the pot, you'll have to put in all $40.

4: Initial bet was (your) $20, SB made it $40, your re-raise must make it $60 (and since you already have $20 in the pot, you must add $40 more).

Your software was correct in every case.

Answer 2

Thanks for looking into this naive question. I have found the answer. The min raise is always equal to 1 BB. Min Raise amount = Call amount + Big Blind amount