What is Technical Debt Ratio?
The estimated cost to fix code issues relative to the cost to build it.
Definition
Technical debt ratio expresses the estimated effort to remediate maintainability issues in a codebase as a percentage of the effort it would take to build it from scratch. Tools like SonarQube compute it from detected code smells and issues.
How it’s measured
Static-analysis tools estimate remediation effort versus development effort and express it as a ratio. Tracked over time per project, it shows whether a codebase is getting more or less maintainable.
What good looks like
Lower is better; many teams target a debt ratio under 5%. The most useful signal is the trend — debt creeping up across releases even while individual PRs pass their quality gate.
Why it matters
Per-PR gates catch increments; nobody watches the integral. A rising debt ratio is the maintainability cost that quietly slows future delivery — and a key lens for whether AI-assisted code is degrading quality faster.
Related terms
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