Standard : Technical Debt Ratio
Description
Technical Debt Ratio measures the proportion of engineering capacity spent addressing known technical debt compared to new feature delivery. It reflects the long-term sustainability of the product.
How to Use
What to Measure
- Time or story points spent on debt remediation in a period.
- Total engineering time or points delivered.
Technical Debt Ratio (%) = (Effort on Debt ÷ Total Effort) × 100
Example: 200 total story points, 50 on debt → 25% ratio.
Instrumentation Tips
- Tag backlog items as debt in the tracking tool.
- Track trends across releases to see whether debt is being addressed.
- Include both planned and unplanned debt work.
Why It Matters
- Maintainability: High unmanaged debt slows future delivery.
- Risk control: Prevents fragility and defects caused by outdated code.
- Engineering health: Improves developer experience and velocity.
Best Practices
- Maintain a visible, prioritised debt register.
- Allocate consistent capacity (e.g. 20%) to debt paydown.
- Celebrate debt reduction alongside feature delivery.
Common Pitfalls
- Not distinguishing between refactoring for feature delivery and debt remediation.
- Allowing urgent feature work to crowd out debt reduction.
- Tracking debt inconsistently across teams.
Signals of Success
- Technical debt ratio declines or stabilises over time.
- Fewer production issues caused by fragile areas.
- Increased delivery speed as debt backlog reduces.
- [[Investment Allocation Ratio]]
- [[Cycle Time]]
- [[System Reliability Metrics]]