The oxidation number of an element in a compound tells you how many electrons it has gained, lost, or shared — a key concept in chemistry for balancing redox reactions and understanding bonding. Enter a chemical formula (like H₂SO₄ or KMnO₄) into the Oxidation Number Calculator to see the oxidation states assigned to each element in the compound, along with the total charge.
Chemical Formula
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Oxidation States
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Total Charge
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An oxidation state (also called oxidation number) is the hypothetical charge of an atom if all of its bonds to other atoms were fully ionic. It helps determine how electrons are distributed in chemical compounds.
Oxidation states are calculated using specific rules: free elements have oxidation state 0, the sum of oxidation states in a neutral compound equals 0, hydrogen is usually +1, oxygen is usually -2, and alkali metals are +1.
Key rules include: free elements = 0, monatomic ions = their charge, hydrogen = +1 (except in hydrides where it's -1), oxygen = -2 (except in peroxides), and the sum must equal the compound's total charge.
Capitalize the first letter of each element symbol and use lowercase for remaining letters (Ca, Fe, Mg). Use parentheses for groups like Ca(OH)2 and numbers as subscripts like H2SO4.
Yes, the calculator can process organic compounds using standard chemical formulas. For complex molecules, enter the molecular formula with proper element symbols and subscripts.
A negative oxidation state indicates the atom has gained electrons compared to its neutral state. Non-metals like oxygen and chlorine often have negative oxidation states in compounds.
If the total charge doesn't equal zero, you may have entered an ionic compound or made an error in the formula. Neutral compounds should always sum to zero, while ions will have a net charge.