Enter the volume of traffic and the capacity of the road into the calculator to determine the Congestion Index. This calculator can also evaluate any of the variables given the others are known.

Congestion Index Formula

The following formula is used to calculate the Congestion Index.

CI = (V / C) * 100


  • CI is the Congestion Index (%)
  • V is the volume of traffic (vehicles per hour)
  • C is the capacity of the road (vehicles per hour)

To calculate the Congestion Index, divide the volume of traffic by the capacity of the road. Multiply the result by 100 to convert it to a percentage. This will give you the Congestion Index, which represents the percentage of the road’s capacity that is being used by traffic.

What is a Congestion Index?

A Congestion Index is a measurement tool used to determine the level of traffic congestion in a particular area.

How to Calculate Congestion Index?

The following steps outline how to calculate the Congestion Index.

  1. First, determine the volume of traffic (V) in vehicles per hour.
  2. Next, determine the capacity of the road (C) in vehicles per hour.
  3. Next, use the formula CI = (V / C) * 100 to calculate the Congestion Index.
  4. Finally, calculate the Congestion Index.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

volume of traffic (V) = 120 vehicles per hour

capacity of the road (C) = 100 vehicles per hour