Purpose

Code Maintainability Rating aims at defining project rating related to the value of Technical Debt Ratio.

How metric helps

Code Maintainability Rating helps to identify the ratio of "Technical-Debt vs. Cost-to-Rewrite". In case the ratio grows significantly, a decision may be made whether it's a good time to rewrite the application instead of spending too much invaluable time reimbursing your debt.

How metric works

Chart overview

Chart shows code maintainability grade for each project child unit - Axis Y on a day by day timeline - Axis X.

Every project child unit is clickable in the legend so that its grade can be shown/hidden on the chart.

Calculation

Maintainability Rating = Technical Debt / Development Cost,

where

• technical debt of the project (= sum of the debt of all issues)
• divided to an estimation of the cost to rewrite the application from scratch

Depending on the ratio of these two indicators, this is then the extent of the Maintainability Rating:

• <=5% of the time that has already gone into the application, the rating is A (best)
• between 6 to 10% the rating is a B
• between 11 to 20% the rating is a C
• between 21 to 50% the rating is a D
• anything over 50% is an E (worst)

RAG thresholds: Red is for E, D; Amber is for C; Green is for B, A.

Data Source

Data for the metric can be collected from Sonar.