Oxidation State Calculator
Determine an element’s oxidation state within a compound or ion.
About Oxidation State Calculator
Oxidation numbers must sum to the overall charge. Assigning oxygen as −2 and hydrogen as +1 lets the unknown element be solved by difference — sulfate gives sulfur as +6. Oxidation states identify what is oxidised and what reduced, which is the prerequisite for balancing any redox equation.
Formula
Oxidation State
Σ oxidation numbers = overall charge; oxygen is normally −2 and hydrogen +1
- oxidation state
- Formal charge assuming all bonds are fully ionic
Worked example
With the default values below, Oxidation State Calculator returns Oxidation State of the Target Element of 6.0000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Overall charge of the speciesaccepts -6–6
- -2
- Number of oxygen atomsaccepts 0–20
- 4
- Number of hydrogen atomsaccepts 0–20
- 0
- Number of the target atomsaccepts 1–20
- 1
- Combined oxidation number of other elementsaccepts -40–40
- 0
Results
- Oxidation State of the Target Element
- 6.0000
- Contribution From Oxygen
- -8
- Contribution From Hydrogen
- 0
- Sum of All Oxidation Numbers
- -2.00
- Classification
- Positive — the element is oxidised
Step by step
- 1Values used
- 2Oxidation State
- 3Oxidation State of the Target Element= 6.0000
- 4Contribution From Oxygen= -8
- 5Contribution From Hydrogen= 0
- 6Sum of All Oxidation Numbers= -2.00
- 7Classification= Positive — the element is oxidised
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Oxidation State calculated?
Σ oxidation numbers = overall charge; oxygen is normally −2 and hydrogen +1 Oxidation numbers must sum to the overall charge. Assigning oxygen as −2 and hydrogen as +1 lets the unknown element be solved by difference — sulfate gives sulfur as +6.
Why does Oxidation State matter?
Oxidation states identify what is oxidised and what reduced, which is the prerequisite for balancing any redox equation.
What values do I need to enter?
This calculator takes 5 inputs: Overall charge of the species, Number of oxygen atoms, Number of hydrogen atoms, Number of the target atoms, Combined oxidation number of other elements. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.