Incorrect negative item rarity calculation

[byoungtech-stack]

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• I'm running the latest version of Path of Building and I've verified this by checking the changelog

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• I've checked that the calculation is supposed to be supported. If it isn't please open a feature request instead (Red text is a feature request).

What platform are you running Path of Building on?

Windows

What is the value from the calculation in-game?

Slain monster item drop rarity modifier -47%

What is the value from the calculation in Path of Building?

Slain monster item drop rarity modifier -50%

How to reproduce the issue

Tested on Ritualist with 'Mystic Attunement' skill point/passive point.

Step 1.) Equip 2 random 'Ventor's Gamble Gold Ring' that has negative item rarity in the explicit lines(use any implicit # as well.)
Step 2.) Equip any 'Ingenuity Utility' belt with any ring bonuses.
Step 3.) Open any attack skill and check your NR bonuses at the bottom.
Step 4.) Import your character into PoB and compare.

PoB for PoE2 build code

PoB Community Fork v0.15.0
Version: 0.15.0 (2026/01/14)

Screenshots

Ingame tooltip:

PoB cal:

[Blitz54]

Please provide an updated build for testing, those steps to reproduce are useless as equipping random gear would not lead us to the same values you have in game. From the second screenshot I think your Ingenuity is corrupted 32%, but that info was not mentioned in your steps, and is very important for us to know.

The "PoB for PoE2 build code" section is for pasting a PoB2 generated build code.

[MrHB212]

I actually looked into it a bit today.

Basically PoB always rounds down while the game rounds depending on the decimal.

[Nightblade]

@MrHB212 Is it possible for you to test how the game rounds "half way" numbers (like 23.50 or 13.50 for example)?

[byoungtech-stack]

Please provide an updated build for testing, those steps to reproduce are useless as equipping random gear would not lead us to the same values you have in game. From the second screenshot I think your Ingenuity is corrupted 32%, but that info was not mentioned in your steps, and is very important for us to know.

The "PoB for PoE2 build code" section is for pasting a PoB2 generated build code.

1.) This bug appears to be happening for all versions of PoB but I just double checked the 'About' section of PoB and do not see any build # specified besides the version # i listed. Is there somewhere else I should check?(see below screenshot)

2.) You are correct, I am using a corrupted Ingenuity belt for my testing. The reason why I stated I tested on Ritualist with 'Mystic Attunement' (key because it gives 0.25% bonuses), equipped any 2 random ventor rings & equipped any ingenuity belt instead of providing the exact values from my items is so anyone can reproduce the bug. No matter what values anyone has on those items, the equation appears to be getting miscalculated somewhere and the end result being the ingame tooltip being slightly different than PoB.

I assume the miscalculation is from the ascendancy passive points (0.25% ring bonuses + the extra ring slot from prereq passive point) instead of from the items themselves but I will leave the real problem solving of that miscalculation up to you mathematician and smart folks :)

[Nightblade]

@byoungtech-stack I think you're confusing "build code" with "version number".

Please do the following:

Then:

Add a comment here and paste it (ctrl+v)

[byoungtech-stack]

@byoungtech-stack I think you're confusing "build code" with "version number".

Please do the following:

Then:

Add a comment here and paste it (ctrl+v)

ahhh!! thank you!!

here you go:(updated build code, i forgot to equip belt)
https://maxroll.gg/poe2/pob/mnd00oze

[MrHB212]

@Nightblade

Ingame:

PoB:

6 * 1.25 = 7.5 so the game does also round down.

[PurpleW1zard]

seems like the correct formula is:

ring_rarity=trunc((enchant+impl+expl)*(1+ingenuity_bonus+ritualist_bonus))

for each ring separately, and then sum all rarity.

with 30% rarity ventor's gamble (12% enchant, 12% implicit, 6% explicit) and 30% ingenuity bonus,
PoB shows 37% item rarity, while in game it's 39%
if you round each of them seperately, you'd get 40%, if you trunc them seperately, you get 37%, but if you sum them all up first, you get 39% (same as in game)

[eMeeMe-pt]

Hi!
I have the same problem.
Hunter Ritualist, with 3x ventors gamble ring (negative rarity) and ingenuity belt.
While POB round up (-102%), the game round down (-99%).
Or POB sum all first and then round, but in game, it round down first and sum later.