vCalc Reviewed
Equation / Last modified by KurtHeckman on 2018/11/16 18:01

The Strain calculator computes the ratio of change in length to original length.

INSTRUCTIONS: Choose units and enter the following:

  • (L)  This is the initial length.
  • (ΔL)  This is the change in length.

Strain (S):  The calculator return the strain as a real number.  However, this can be automatically converted to percentage via the pull-down menu.

The Math / Science

This Strain equation computes engineering strain from the simplest definition, where Strain is simply a ration of the change in length to the original length.  The formula for strain is:

        ε = ΔL / L


  • ε is strain
  • ΔL is the change in elongation.
  • L is the original length

Related Calculators

Engineering strain is defined in terms of the change in length of a physical element (ΔL) divided by the original length of the physical element (L).1


  1. ^ Fundamentals of Engineering. 8th edition, 2nd Revision.  National Council of Examiners for Engineering and Surveying (NCEES) - 2001. ISBN 978-1-932613-59-9.  pg 33