Chemistry
Degree of Unsaturation Calculator
Count the rings and pi bonds hidden in a molecular formula before you draw the structure.
Your inputs
Change any value to update the result instantly.
Degrees of unsaturation
4
Meaning
Any mix of 4 rings and pi bonds
Benzene ring?
Four or more units is the classic sign of an aromatic ring
Hydrogens in the saturated version
14
Hydrogen deficiency
8
Oxygen and sulfur do not appear in the formula because they form two bonds and do not change the hydrogen count. A half value means the formula as typed cannot be a neutral molecule.
What this calculator does
Counts the rings plus pi bonds implied by a molecular formula.
What your result means
Each unit is one ring or one double bond; four or more often signals an aromatic ring.
Formula and working
DoU = (2C + 2 + N − H − X) / 2
- 1
Collect the inputs
Carbon atoms (C) = 6; Hydrogen atoms (H) = 6; Nitrogen atoms (N) = 0; Halogen atoms (F, Cl, Br, I) = 0
- 2
Apply the formula
DoU = (2C + 2 + N − H − X) / 2
- 3
Result
Degrees of unsaturation = 4
Frequently asked questions
Symbols and assumptions
- C, H, N, X
- Atom counts, X being halogens
- DoU
- Degrees of unsaturation
- • The formula is for a neutral molecule.
- • Oxygen and sulfur are divalent and do not enter the formula.
Sources and review
Reviewed 2026-09-22 · Next review 2027-09-22
- • A half value means the formula as typed cannot be a neutral molecule.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Report a mistake or request an improvement
Tell us if a formula, unit, explanation, or result needs attention. Your message will include this calculator’s name and page.
Related calculators
Combustion Analysis Calculator
Turn the carbon dioxide and water collected from burning a sample into its empirical and molecular formula.
Combustion Reaction Calculator
Write the balanced combustion equation for any CxHyOz fuel and see how much oxygen it needs.
Crude Protein Calculator
Convert a Kjeldahl nitrogen titration into the nitrogen and crude protein content of a sample.
Double Bond Equivalent Calculator
Work out the DBE of a formula from mass spectrometry and split it into likely rings and double bonds.
Liquid Ethylene Density Calculator
Convert a measured mass and volume of liquid ethylene into density, with the reference saturated-liquid values alongside.
Activity Coefficient Calculator
Estimate the activity coefficient of an ion in a dilute solution using the Debye-Hückel limiting law.