How to calculate PLO raise from straddle

[MisterD]

Let’s assume a 6-player 5/5 table with a Mississippi straddle from the button up to $20. To make the math easy, let’s also assume that everyone limps back to the Button. He then announces a pot-sized raise.

He has no call to make, so the pot is currently 120. Does he make his total bet 140?

Do we count the straddle bet as part of the pot in order to calculate the raise?

[Dave Miller]

...
Do we count the straddle bet as part of the pot in order to calculate the raise?

YES.

You’re over-thinking it.

It’s part of the pot if anyone else wanted to do a pot size raise, right? Nothing changes if the raiser is the straddler. 

[Boris]

Hello MisterD,
Initial bet is never took under consideration when it comes to calculate the max raise in Pot Limit.
So, in your case, the max raise amount allowed is 140.
3 times last highest bet added to everything else
So 3x20 (last highest bet) + 4x20 (other bets)