How to Read a Civil Scale Ruler

As engineers are designing roads, topographical structures and water mains, they use scales (size reduction) to transfer the design concept to a manageable size set of drawings that provide two- or three-dimensional representation of the project. Civil or engineer rulers (scales) refer to the tools that engineers and plan reviewers use to measure these projects as they are designing and building them. Accurately reading and interpreting civil scales, an important engineering skill, is vital for the success of any construction project.

Engineers use civil scales to measure objects they are designing and building.
  1. Align the zero on your civil scale ruler with one end of the object you are measuring. This end represents the starting point.
  2. Identify the object's end point and read the ruler's corresponding number that aligns with this end point.
  3. Multiply the value you identify on the civil scale by 10 to get the actual length of the object you are measuring. If the corresponding number that aligns with your object's end point is 5, for example, you interpret the length of the object as 50 feet.
  4. Know that the small lines between the whole numbers on your civil ruler represent individual feet. If the corresponding number on the scale falls two marks to the right of the whole number 4, for example, you read the length as 42 feet.


  • Each civil scale has a dimensional relationship that is displayed as a whole number to the left of the number line on the ruler. This number represents the scale the engineer uses when transferring the object measurement into reduced-size drawing. A civil ruler with the number 10, for example, indicates that the ruler uses a 1:10 dimensional relationship. This means that an object that measures 10 feet using this civil scale will measure one inch in the engineer drawings.


  • You should never use your civil scale to draw lines. Civil rulers should only be used for measuring.

About the Author

Candi Lemon has a passion for reading and writing. She combines her love for traveling, food and the outdoors in her personal blog and for Demand Studios. Her articles appear on eHow and Trails. Lemon holds a Bachelor of Science in medical technology from the University of Michigan.

Photo Credits

  • blue print building plans with ruler image by Stephen Orsillo from Fotolia.com