JMeter – Uniform Random Timer

As the name suggested, the JMeter Uniform Random Timer is used to generate and add the random delay in a uniform manner before the execution of a sampler. This timer is based on a random function and generates a random amount of time (delay), with each time interval having the same probability of occurring. Hence it is called ‘Uniform Random Timer’. The delay (think) time is the sum of the random value and the offset value specified in the timer.

How to add a ‘Uniform Random Timer’?

Follow the below steps to add the Uniform Random Timer in the script:

  1. Select any appropriate element from the below list where you want to add the timer
    1. Test Plan
    2. Thread Group
    3. Controller
    4. Sampler
  2. Right-click on the element
  3. Hover the mouse on ‘Add’
  4. Hover the mouse on ‘Timers’
  5. Click ‘Uniform Random Timer’
JMeter - Uniform Random Timer
Figure 01: JMeter – Uniform Random Timer

What are the input fields ‘Uniform Random Timer’?

‘Uniform Random Timer’ has the following input fields:

  1. Name: To provide the name of the timer
  2. Comments: To provide arbitrary comments (if any)
  3. Random Delay Maximum (in milliseconds): Specify the maximum number for delay. JMeter generates the random number less than or equal to the provided value. 
  4. Constant Delay Offset (in milliseconds): The value shows a constant delay which will be added in a random number.


Consider the value of the Random Delay Maximum is 5000 and the Constant Delay offset is 1000. JMeter generates the random number as 3000 then the final delay will be 4000 milliseconds:

Uniform Random Timer Delay = 3000 + 1000  

Additional Information:

  • The Uniform Random timer is processed before each sampler in the scope in which it is found; if there are several timers in the same scope, all the timers will be processed before each sampler.
  • Timers are only processed in conjunction with a sampler. A timer which is not in the same scope as a sampler will not be processed at all.
  • To apply the timer to a single sampler, add the Uniform Random Timer as a child element of the sampler.
  • To apply the timer after a sampler, either add the Uniform Random Timer as a child element of the next sampler or as a child element of a dummy sampler.

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