Both of them say they increase the carrying capacity of the character: 300% for the Heavyload Belt and Burdenless by 50%.
I have a feeling they won't stack due to both using percentages, but there is no info on the Internet I can find.
Role-playing Games Stack Exchange is a question and answer site for gamemasters and players of tabletop, paper-and-pencil role-playing games. It only takes a minute to sign up.
Sign up to join this communityBoth of them say they increase the carrying capacity of the character: 300% for the Heavyload Belt and Burdenless by 50%.
I have a feeling they won't stack due to both using percentages, but there is no info on the Internet I can find.
They do stack. Absent any rule that says otherwise (and Pathfinder is absent of rules that say otherwise), the math works exactly like normal math: Ant Hauls' 3× carrying capacity and Burdenless armor's 50% increase (which is the same as 1.5×) just straight multiply together to give 4.5× carrying capacity.
The only alteration of multiplication rules in Pathfinder is for modifiers to rolls, which use special rules (PFRPG Core Rulebook, p. 12) to keep roll modifiers from being multiplied into the stratosphere. Carrying capacity isn't a roll bonus or penalty, so multipliers to it behave as-written, in normal mathy ways.