Double Bond Equivalent (DBE) Calculator

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Number of carbon atoms in the molecular formula.
Number of hydrogen atoms. Includes deuterium (D) if present.
Oxygen does not change the DBE value (it is divalent like the implicit chain). Enter it for completeness.
Trivalent nitrogen adds 1/2 to DBE per atom.
Total count of all halogen atoms. Each halogen subtracts 1/2 from DBE, the same as hydrogen.
Trivalent phosphorus is treated like nitrogen: adds 1/2 per atom.
Tetravalent silicon is treated like carbon: adds 1 per atom.
Double Bond Equivalent (DBE)Four degrees - possible benzene ring
4

Total rings + pi bonds (double bonds count 1, triple bonds count 2)

Saturated formula H count14
H deficiency8
Result validityValid - closed-shell neutral molecule
4
Saturated<1Low unsaturation1-4Aromatic4-5Highly unsaturated5+

DBE = 4 for C6H6O1

  • A DBE of 4 is characteristic of a benzene ring (three double bonds + one ring = 4).
  • If C is at least 6 and H matches, an aromatic ring is very likely.

Next stepA DBE of 4 or more strongly suggests an aromatic ring. Combine with NMR chemical shift data (aromatic protons at 7-9 ppm) to confirm.

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