How to calculate Crit chance with this bow?

Normal Bow without crit decress from crucible.

Bow with crucible option:

Crucible - crit chance:

POB - Crit chance with this bow


So whats correct to calculate that if pob doesn't know?

That "-3% to crit chance" is a flat -3 to the base crit chance listed on your bow (before any crit modifiers for that bow). Essentially it's MUCH more impactful than it looks.

Here's an example, if you have a Harbinger Bow base (5.00% base crit but it has an implicit that gives 50% increased crit chance, for a total base crit chance of 7.50% while blank), the -3% would mean instead of a 5% base, it now has a 2% base. The 50% increased on it would then take that to 3%. As you can see, that seemingly minor change knocks the blank bow from 7.5% crit chance to 3%. Then any crit chance investment you have is multiplied on top of THAT.