Bond Length Calculator

Enter the covalent radii of two atoms and the electronegativity of each atom into the calculator to determine the bond length.

Bond Length Formula

The following formula is used to calculate a bond length.

dA-B = rA + rB – .09 * (xA – xB)

  • Where dA-B is the distance between the nuclei of atoms A and B
  • rA is the covalent radius of atom A
  • rA is the covalent radius of atom B
  • xA is the electronegativity of atom A
  • xB is the electronegativity of atom B

Bond Length Definition

What is a bond length? A bond length is a measure of the distance between the centers of two bonded nuclei. The distance is typically measured in picometer.


How to calculate bond length?

  1. First, determine the lengths of the covalent radii.

    For this example, the radius of atom A is 24 picometers and the radius of atom B is 32 picometers.

  2. Next, determine the electronegativity of atom A.

    For this problem, atom A has an electronegativity of 3.2.

  3. Next, determine the electronegativity of atom B.

    The electronegativity of atom B is found to be 2.1.

  4. Finally, calculate the bond length.

    Using the formula above, the bong length is found to be dA-B= 24+32-.09*(3.2-2.1) = 55.901.

About Bond Length

Is bond length an average? In general, when calculating a bond length, the resulting answer is an average length between nuclei.

How does bond length change with bond order? As bond order increases, the bond length will decrease. For example, a third bond order will have a smaller bond length than a second bond order.

bond length calculator
bond length formula