+10% Projectile damage doesn't boost my DPS as expected

I'm a bow user, and this morning I grabbed a +10% node of projectile damage in my tree. Since I was at +55% previously (at least that's what POE builder says), and since proj. damage is supposed to scale up everything the same way (phys, elem converted from phys, and flat elemental), I was expecting a DPS multiplier of 165/155, i.e. +6% approximately.

Instead of what I got:

default attack: +3%
Frenzy (+Wed/PhysToLight/Culling): +1,4%
Tornado Shot (+Wed/LPM/PhysToLight/PPAD): +2,5%



I'm probably missing something. Can someone explain? I have no special unique, btw.

Increased projectile damage stacks additively with all your other increased damage, not just other sources of projectile damage. This means your physical damage, bow damage, etc. The number you're adding 10% to will thus be a lot bigger, and your damage increase smaller.

Your damages are calculated like this :

(Increased physical + increased projectile + any increased that benefits your attack)

*

(More multiplier n°1)

*

(More multiplier n°2)

*

(More multiplier n°x)

Which means that if you already have 100% increased (adding all your increased damage bonuses), getting an additional 10% will bump you from 1+(100/100)=2 to 1+(110/100) =2.1, and 2.1/2 = 1.05, so from a 10% increase you actually get a 5% more damage.

Ok thanks, understood. You are perfectly right.
I thought that it may be an independant boost, but likely I've confused with the PPAD gem.