Measuring ROI of a Software Rewrite

Rewrites are controversial. Joel Spolsky once said: “Never rewrite from scratch.” But let’s be real—sometimes legacy codebases are beyond saving.

The key question: How do you measure ROI so your rewrite isn’t just a tech vanity project?

Dev-Centric ROI Metrics:

1. Cycle time – How long does it take to ship a new feature?
2. Bug density – Are you fighting the same fires every sprint?
3. Infra costs – Are outdated systems forcing expensive workarounds?
4. Team velocity & morale – Are devs frustrated or motivated?

Legacy app: 3 weeks for new feature
Rewritten app: 5 days for new feature
=> 4x improvement in cycle time = direct business ROI

Watch Out:
Rewrites can balloon scope—define an MVP for your rewrite.

Don’t just copy old architecture in a new language—modernize.

Use metrics dashboards to prove impact post-launch.

👉 Bottom line: A rewrite should be treated like any other investment—quantify ROI with measurable business and dev metrics, not just gut feeling.
What’s your take—rewrite or refactor?