By Arjun Mehta
GitHub Copilot costs $100/month per engineer. For a 50-person team, that's $60,000/year.
Is it worth it?
Most teams don't measure ROI. They assume it's positive. But the data is messier than they think.
What to Measure
Metric 1: Code Generation Speed
Baseline (without Copilot): Average engineer writes 100 lines per day. 50 engineers × 100 = 5,000 lines/day.
With Copilot: Average engineer writes 150 lines per day. 50 engineers × 150 = 7,500 lines/day.
Improvement: 50% more lines generated.
Metric 2: Code Review Time
Baseline: PR review takes 2 hours.
With Copilot (AI code needs more review): PR review takes 3 hours.
Impact: +50 hours/week on reviews (negative).
Metric 3: Refactoring Time
Baseline: Engineers spend 20% on refactoring.
With Copilot (more debt to refactor): Engineers spend 30% on refactoring.
Impact: +10% on refactoring (negative).
Metric 4: Test Coverage
Baseline: 85% coverage. With Copilot: 75% coverage (tests aren't generated as fast).
Impact: Lower coverage, higher risk (negative).
Metric 5: Defect Rate
Baseline: 1 bug per 100 lines. With Copilot: 2 bugs per 100 lines (AI code has more issues).
Impact: More bugs, more debugging (negative).
Calculating ROI
Time Saved
50% more code generated. But 50% more time on review. Net time saved: 0.
Quality Impact
10% less coverage. 2x bug rate. 10% more refactoring. Net quality: Negative.
Cost
$60,000/year.
ROI
Benefit: None (or negative). Cost: $60,000. ROI: Negative.
When Copilot Has Positive ROI
Copilot is worth it when:
- You have strong code review. Catch issues before merge.
- You use it for the right tasks. Tests, docs, boilerplate (not core logic).
- You have strong guardrails. Linting, type checking, security scanning.
- Your team is experienced. Juniors can't review AI code effectively.
If these conditions aren't met, Copilot creates more problems than it solves.
The Right Approach
- Measure baseline. What are your current code metrics?
- Pilot Copilot. Use it with 10 engineers for 3 months.
- Measure impact. Did code quality improve or degrade?
- Calculate ROI. Cost vs benefit.
- Make decision. Expand, optimize, or discontinue.
Don't assume Copilot is positive. Measure it.
Reality Check
Most teams find that Copilot:
Accelerates code generation by 20-30% (not 50%). Increases review burden by 30-50%. Decreases code quality slightly. Increases technical debt.
Net ROI: Slightly positive if you have strong guardrails, slightly negative if you don't.
For most teams, Copilot is worth it. But not because it saves time. Because it reduces friction. Engineers enjoy writing with Copilot. Less context switching. Less boilerplate writing.
The value is in experience, not in measurable productivity improvement.
Frequently Asked Questions
Shouldn't Copilot improve velocity? It improves code generation speed, but not overall velocity if code quality suffers and review burden increases. Total time per feature might be similar.
Can junior engineers use Copilot effectively? Not effectively. They can't review AI code properly. Copilot is best for experienced engineers who can tell good generated code from bad.
What's the real ROI of Copilot? Experience and reduced friction. Engineers enjoy writing with Copilot. That matters for morale and retention.