Enter the speed (mph) and the reaction time (ms) into the Reaction Distance Calculator. The calculator will evaluate and display the Reaction Distance. 

Reaction Distance Formula

The following formula is used to calculate the Reaction Distance. 

Dreact = S*5280/3600 * T/1000

  • Where Dreact is the Reaction Distance (ft)
  • S is the speed (mph) 
  • T is the reaction time (ms) 

How to Calculate Reaction Distance?

The following example problems outline how to calculate Reaction Distance.

Example Problem #1:

  1. First, determine the speed (mph). 
    • The speed (mph) is given as: 60.
  2. Next, determine the reaction time (ms). 
    • The reaction time (ms) is provided as: 500.
  3. Finally, calculate the Reaction Distance using the equation above: 

Dreact = S*5280/3600 * T/1000

The values given above are inserted into the equation below and the solution is calculated:

Dreact = 60*5280/3600 * 500/1000 = 44 (ft)


Example Problem #2: 

For this problem, the variables needed are provided below:

speed (mph) = 70

reaction time (ms) = 350

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer. 

Dreact = S*5280/3600 * T/1000 = ?