Understanding Technical Debt Ratio
How we calculate. TDR % = remediation cost ÷ development cost × 100 (SQALE-style). The form uses the same arithmetic as the worked examples on this page. See our methodology and accuracy policy.
Real-world scenario: A typical Technical Debt Ratio case uses remediation cost 40000 and development cost 500000. Enter the same figures below to reproduce the worked path.
What is Technical Debt Ratio?
Sonar/SQALE-inspired ratio. Lower is better; thresholds vary by org risk appetite.
- Remediation = estimated fix cost for debt items
- Development cost = build cost or replacement value
- Use consistent costing
The Formula
Worked Example
Common Use Cases
- Architecture reviews: debt posture
- Investor/board packs: quality risk
- Sprint allocation: debt budget
Pro Tips
- Don’t inflate remediation
- Separate intentional debt
- Trend monthly
Limitations: Technical Debt Ratio results are educational software estimation aids—not bids, contracts, or performance scores. Calibrate models to your organization’s history.
FAQ
Is this the same as interest on debt?
No—this is a stock ratio of remediation vs build cost, not ongoing interest rate.
What if development cost is 0?
Ratio is undefined—enter a positive development cost basis.
Authoritative References
For estimation and quality models, consult:
- COCOMO — Constructive Cost Model overview
- IFPUG — function point standards
- SEI / Carnegie Mellon — software engineering practice