how much +dex do i need to get + 1 critical strike?

1 dex<crit strike
2dex>crit strike

2 dex will give you the same +to crit as 1 crit strike, but what people never see is if you use crit strike you miss out on the attack speed, defense from crits, and extra damage for crits

hmm, cool, thx 4 the info.

wrong, dex gives diminishing returns to %crit chance, so unless your dex is extremely low 2 dex will not give the same % to crit as 1 crit.

the generally accepted conversion is 2 dex = 1 crit, dependant on the rest of your stats/gear of course.