Free · Organic chemistry calculators 🛢️

Organic Formula Degree of Unsaturation

Calculate double-bond equivalents from carbon, hydrogen, nitrogen and halogen counts under the standard neutral-molecule valence model.

Calculator inputs

Loading calculator…

Enter the known values in the units shown. Results update as you type.
Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
Use the worked example to check the method. Reset restores the starting fields.

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

For C₆H₆ with no nitrogen or halogens, DBE = 6 + 1 − 6/2 = 4. The formula alone does not determine which rings and multiple bonds are present.

DBE = C + 1 − (H + halogens) / 2 + N / 2

Enter these known values and leave the other values blank.

Enter nonnegative whole atom counts and explicit zeroes for absent elements. The model uses the usual valences C = 4, H/halogen = 1 and N = 3.
Oxygen with its usual valence of two does not change this formula. Oxygen is therefore omitted from the entry fields.
The supported interpretation is a neutral, closed-shell organic molecule with standard valences. Negative or fractional DBE results are rejected; radicals, ions and unusual valence states need a different analysis.
Each ring or double bond contributes one DBE; each triple bond contributes two. DBE does not identify a unique structure or prove that an entered molecular formula is chemically feasible.

No. It could also represent one triple bond, two rings, or a ring plus a double bond under the stated model.

Bookify requires a nonnegative whole degree of unsaturation for the stated neutral, closed-shell standard-valence model.