How to calculate the defect density in software products

Defect density could be defined as the value of the total defects which are known to the size of the software product calculated. i.e. Defect Density= Total defects/Size

For better understanding, consider the following example.

Suppose you have a software product which has been integrated with the 4 modules and you found the following bugs in each of the modules.

• Module 1 = 20 bugs
• Module 2 = 30 bugs
• Module 3 = 50 bugs
• Module 4 = 60 bugs

And the total line of code for each module is

• Module 1 = 1200 LOC
• Module 2 = 3023 LOC
• Module 3 = 5034 LOC
• Module 4 = 6032 LOC

Then, we calculate defect density as

Total bugs = 20+30+50+60 = 160

Size= 15289 LOC

Defect Density =  160/15289 = 0.01046504 defects/loc = 10.465 defects/Kloc

We can use defect density to calculate the following:

1. We can predict the remaining defect in the software product by using the defect density.
2. We can determine whether our testing is sufficient before the release.
3. We can ensure a database of standard defect densities.

Hope this gives you a good understanding of Defect Density.