Enter the disk utilization (%) and the interval length (sec) into the Calculator. The calculator will evaluate the Disk Service Time. 

Disk Service Time Formula

DAT = U/100 * IL


  • DAT is the Disk Service Time (sec)
  • U is the disk utilization (%)
  • UL is the interval length (sec)

To calculate Disk Service Time, divide the disk utilization by 100, then multiply by the interval length.

How to Calculate Disk Service Time?

The following steps outline how to calculate the Disk Service Time.

  1. First, determine the disk utilization (%). 
  2. Next, determine the interval length (sec). 
  3. Next, gather the formula from above = DAT = U/100 * IL.
  4. Finally, calculate the Disk Service Time.
  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.

disk utilization (%) = 78

interval length (sec) = 234


What is disk utilization and why is it important?
Disk utilization refers to the percentage of time the disk is actively serving requests compared to the total available time. High disk utilization can indicate that a disk is heavily used and may become a bottleneck in the system, affecting overall performance.

How can improving disk service time benefit a system’s performance?
Improving disk service time can significantly enhance a system’s performance by reducing the wait time for data to be read from or written to the disk. This can lead to faster application response times and improved throughput for data-intensive operations.

What factors can affect disk service time?
Several factors can affect disk service time, including disk type (SSD vs. HDD), the size and type of files being accessed, the level of disk fragmentation, and the disk’s interface with the computer (e.g., SATA, NVMe).

Can disk service time vary for different operations on the same disk?
Yes, disk service time can vary for different operations on the same disk. For example, sequential read/write operations typically have faster service times compared to random read/write operations due to the way data is accessed and stored on the disk.