Oxidation state calculator

One unknown element with default rules (O, H, F, group 1/2…).

Calculator

Model / formula

Assign one unknown element; ionic charge on the whole formula

Formula

Overall charge

Element to solve

Peroxide / superoxide-style: use O = −1 instead of −2

Result

Oxidation state of Fe = +3

Optional peroxide checkbox sets O = −1.

Educational use only. Double-check values for labs, homework, and exams.