Hello,
I use a "Bet/Raise % of Pot" hotkey on PokerStars.
I don't know how soft calculates raise amount when I want to raise with this hotkey.
I made some tests, but I am not able to fit values to the formula.

My tests, legend first

pot before bet / opponent bet / my raise / % of pot raised hotkey

60 chips(3bb) / 40 chips(2bb) / 110 chips(5.5bb) / 50 %

120 chips(6bb) / 120 chips(6bb) / 242 chips(12.1bb) / 34%

Do you have any ideas how I can predict amount of raise with this hotkey?

Regards,

Pot-sized raises confuse a lot of people.

When you make a "pot-sized raise" (which will lay 2:1 odds on a call), you have to include the price of calling to calculate the pot, and then add the raise on top of that to make it a pot-sized raise.
e.g. In the first example, there is 60+40 = 100 in the pot after villain's bet. To make a pot-sized raise, you need to call 40 (to make it 140) and then you raise that 140 on top of the current price (40) which would be a raise to 180. Making it 180 would constitute a pot-sized raise, since it would lay odds of 280:140 = 2:1 on a call.

With this same example, you can see that you need to raise by 140 on top of villain's bet to make it a pot-sized bet, so a half-pot raise would be to half of that or 70. 70 on top of the 40 makes it 110.

In the second example, a pot-sized raise would be to 120+120+120+120 = 480, which is a raise of 360 more than the last bet. So if a pot-sized raise means "add 360 on to the last bet", a 34% pot-raise would be 34% of 360 = 122.4 on top of villain's 120 bet. i.e. 242.4.

Personally if I want to raise to 120, I'll either move the slider/mouse wheel to 120 or type 120. Then again I'm not playing that many tables chasing SNE and have time to do so

You'll get SNE one day pal.

Something relating to this thread I wondered about (I don't play PLO) a pot sized bet is always in relation to the last person to bet?

Example

UTG opens, you call OTB and BB calls.

Let's say the pot is 10bb

BB checks, UTG bets pot (10bb) and you raise by pot (40bb). This means that if UTG wants to call he has to call 30bb into a 60bb pot. But the BB has to call 40bb into a pot of 60bb which is worse than 2:1. So you couldn't ever bet enough to offer the BB 2:1 on a call in this spot?

A pot-sized bet (or raise) will always give direct odds of 2:1 on a call for the previous bettor (or caller of the last bet) if no one else cold-calls before the action comes back to him. Anyone else would have to cold-call with even worse odds. If you wanted to give the BB odds of 2:1 in your example, you'd just minraise to 20 on the flop, as then the pot would be 40bb and he'd need to call 20bb. Unfortunately, this cheap price means that UTG would get stupidly good odds to call whether the BB calls or folds. (e.g. If you minraise to 20 and the BB calls, the pot is 60 and UTG only needs to call 10bb, so has odds of 6:1).
Potting it generally works well multiway, as it means even the guy with the best odds needs about 33.33% realizable equity to continue. Anyone else gets a worse price, so needs even more equity.

One of the "problems" with pot-limit games, is that if another player (e.g. the BB) cold-calls, the initial bettor now has better odds than 2:1. This is one of the problems with playing multiway. Someone (a fish) can make a terrible cold-call when he's not closing the action, that accidentally prices in the player you were trying to fold out! (e.g. UTG bets 10 into 10, you pot-raise to 40, BB cold-calls and now the pot is 100 and UTG only needs to call 30, so he's getting 10:3 on a call, so only needs 23% equity, instead of the 33.3% he'd need if BB had folded).