Created By : Rina Nayak

Reviewed By : Rajashekhar Valipishetty

Last Updated : Apr 29, 2023

The Oxidation Number Calculator is a free online tool that displays a chemical compound's oxidation number. The online oxidation number calculator tool speeds up the calculation and shows the oxidation number in a matter of seconds.

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What does Oxidation Number mean?

The oxidation number is used in chemistry to keep track of the electrons in an atom. It is a number that is assigned to the atoms of a chemical substance in general. The oxidation number can be positive, negative, or zero. It denotes the loss or gain of electrons in the atom. The change in oxidation number will let us follow the transfer of electrons in a chemical reaction. The oxidation number does not necessarily match the molecule's actual charge.

How to Use the Oxidation Number Calculator?

The following steps denote how to use the oxidation number calculator

  • Fill in the appropriate input form with the chemical substance.
  • To acquire the result, click the "Calculate Oxidation Number" button.
  • Finally, in the new window, the oxidation number of the chemical compound will be presented.

How to find Oxidation Number of an Element in Chemical Compound?

Go through the simple steps listed below to find the Oxidation Number of an Element in Chemical Compound. They are as follows

  • Consider any chemical compound
  • After that refer to the rules of finding oxidation numbers.
  • As per the rules mention the oxidation number of the element above the symbol and total number of atoms below the symbol.
  • Evaluate the oxidation number and decide the result.

Rules to Compute Oxidation Number of an Element

  • Oxidation number of a free element is zero.
  • Oxidation number of a monatomic ion is equal to charge of that ion.
  • The oxidation number of Hydrogen H is +1, but it is -1 when combined with less electronegative elements.
  • Oxidation number of Oxygen O in compounds is -2, but it is -1 in peroxides.
  • Oxidation number of Group 1 element in compound is +1.
  • Oxidation number of Group 2 element in compound is +2.
  • Oxidation number of Group 17 element in a binary compound is -1.
  • The sum of oxidation numbers of all the atoms in a neutral compound is 0.
  • The sum of oxidation numbers in a poly atomic ion is equal to the charge of ion.

Points to Remember while using Oxidation Number Calculator

You only need to follow a few simple steps to use the oxidation number calculator and they are outlined for your reference. They are as such

  • Correctly write the compound's chemical formula. Pay great attention to capital and small letters when creating the chemical formula. The calculator will not recognise the chemical if you use CAOH2 instead of CaOH.
  • Fill in the blanks with the correct number of atoms for each element in the compound. Remember that if you add more atoms of an element by accident or on purpose, the fundamental nature of your substance will alter. The oxidation number of each reactive element will eventually change. You can use our equation balancer to double-check the number of atoms in a compound.
  • When writing chemical formulas, avoid using extra brackets [] or parentheses ().
  • After adding the formula, wait a few seconds before clicking the balance or compute button.

Oxidation Number Examples

Example 1: Find the Oxidation Number of Metal in the Complex Compound Ni(CO)4.


The complex's overall charge is zero. CO is a non-radioactive chemical.

State of oxidation → x + (4*0) = 0: x = 0

The species' atoms → Ni 4 CO

Nickel is similarly in a condition of zero oxidation.

Example 2: Find the Oxidation Number of Metal in the Complex Compound[CoCl2(NH3)4]Cl


The ionic forms of the complex are as follows CoCl2(NH3)4]+Cl-

With a unitary positive charge, metal is in a cationic compound. Chlorine has a unit negative charge, while ammonia is a neutral ligand.

Number of oxidations of CoCl2(NH3)4]+ = Oxidation number of (Co + 2Cl + 4×0) = +1.

State of oxidation → x + (2*-1) + 4*0 = +1: x = +3

The species' atoms → Co 2Cl 4 NH3

Cobalt oxidation number in the complex = +3

FAQ’s on Oxidation Number Calculator

1. What does it mean to be in an oxidation state?

The charge of an atom following the ionic approximation of its bonds is known as its oxidation state.

2. In H3AsO3, what is the oxidation number of As?

Arsenic has an oxidation number of +5 in H3AsO3 (arsenious acid).

Moles = mass of the substance in grams/molecular weight.

3. What is the oxidation number of every element in Group 18?

Group 18 elements have no oxidation state. They have a full octet, which means they don't lose or gain electrons.