Most Potassium or Sodium Hydroxide is not 100% pure so you will need to adjust the base amount to take into account for this.

Base Amount  @ 100% = 7gr (5gr for NaOH)
Assuming purity of 90%:

90/100 = 0.9
7 / 0.9 = 7.78

Adjusted Base amount  @ 90% = 7.78gr

Note: Substitute the 7gr base amount for Potassium Hydroxide (KOH) for 5gr base amount for Sodium Hydroxide (NaOH) then apply the same formula.