The Question Every CTO Asks First
You have a legacy system. Maybe it's a 15-year-old .NET monolith running on Windows Server 2012. Maybe it's a PHP application held together with jQuery patches and a prayer. Whatever it is, leadership is finally ready to talk about modernization -- and before any budget can be approved, someone asks the obvious question:
"What's this going to cost us?"
But before you can answer that question, you need to answer a smaller one first: What does it cost just to figure out what we have?
That first step -- the assessment -- is what we're breaking down today. We've done hundreds of these. We've seen companies spend $150,000 on reports that gathered dust, and others get everything they needed in an afternoon. Here's what actually drives the cost, and what options you really have.
What a Codebase Assessment Actually Includes
Before comparing prices, it's worth being precise about what you're buying. A proper legacy codebase assessment should deliver answers to these questions:
- How big is the codebase? Total lines of code, number of files, languages used, and how that breaks down by module or service.
- How healthy is it? Cyclomatic complexity, code duplication, test coverage, dependency freshness, and security vulnerability counts.
- What does it actually do? Business logic mapping -- understanding what the code does beyond what documentation says.
- What's the risk? Identifying the landmines: deprecated libraries, hardcoded credentials, outdated frameworks with known CVEs.
- What will modernization take? A realistic estimate of effort in hours, team size, and timeline to migrate, refactor, or rebuild.
- What's the priority order? Which problems need fixing now, which can wait, and which are actually fine.
Some assessments stop at the first two. The valuable ones deliver all six. Keep that distinction in mind as we walk through your options.
Option 1: The DIY Assessment
What it involves
You assign your own engineers to audit the codebase. They run static analysis tools (SonarQube, ESLint, ReSharper), document what they find, and produce a report. Maybe you bring in a senior architect for a week to review the findings.
Real cost breakdown
| Item | Estimate |
|---|---|
| 2 senior engineers, 2-3 weeks | $20,000-$35,000 (opportunity cost) |
| Static analysis tooling (SonarQube, etc.) | $0-$15,000/year |
| 1 architect review week | $5,000-$12,000 |
| Total | $25,000-$62,000 |
What you get
A report written by people who may be too close to the codebase to see it objectively. Internal teams often underestimate problems they created, overestimate effort for areas they're unfamiliar with, and miss security issues entirely because nobody on the team has a security background.
The hidden problem
Your best engineers spend 3 weeks not building anything. In a company where engineering velocity is already a pain point, that's a significant sacrifice -- and the output quality is highly variable depending on who you assign.
Best for
Teams with a strong internal architecture practice, low time pressure, and codebases under 50K lines.
Option 2: A Big Consulting Firm
What it involves
You engage a Tier 1 or Tier 2 consulting firm (Accenture, Deloitte, Cognizant, IBM, etc.) for a formal "Application Modernization Assessment." They send a team, run their proprietary methodology, interview stakeholders, and deliver a polished deck and a detailed roadmap.
Real cost breakdown
| Firm Tier | Typical Engagement | Cost Range |
|---|---|---|
| Tier 1 (Accenture, Deloitte, IBM) | 6-12 weeks | $150,000-$500,000+ |
| Tier 2 (regional SI firms) | 4-8 weeks | $50,000-$150,000 |
| Boutique specialists | 2-4 weeks | $15,000-$60,000 |
What you get
A very thorough report with executive presentation materials. Stakeholder alignment. A vendor-neutral (in theory) roadmap. These engagements can be genuinely excellent -- especially when the team assigned has deep relevant experience.
The hidden problem
Two things consistently frustrate companies after these engagements:
- The "sell-up" risk: Large consulting firms have a financial incentive to recommend the most expensive path forward -- typically a multi-year engagement with them. The assessment is sometimes a loss-leader designed to justify a $2M engagement.
- The analyst gap: The senior consultants who pitch you may not be the analysts who actually audit your code. Junior analysts doing the hands-on technical work is common, and it shows in the output.
Best for
Enterprise organizations with complex regulatory requirements, large stakeholder groups who need executive-level buy-in, and budgets to match.
Option 3: A Boutique Technical Consultancy
What it involves
A specialist firm (like Studio X Consulting) assigns senior engineers to directly analyze your codebase. Less overhead, more technical depth. The people reviewing your code are typically the same people who'd be modernizing it.
Real cost breakdown
| Codebase Size | Typical Timeline | Cost Range |
|---|---|---|
| Small (<50K LOC) | 3-5 days | $5,000-$15,000 |
| Medium (50K-250K LOC) | 1-2 weeks | $15,000-$40,000 |
| Large (250K-1M+ LOC) | 2-4 weeks | $40,000-$100,000 |
What you get
Typically the best technical depth-per-dollar ratio. Boutique firms live and die by referrals, so there's a strong incentive to deliver real value rather than fluff. You also tend to get honest answers -- including "this part of your codebase is actually fine, don't touch it."
The hidden problem
Quality varies enormously between firms. Some boutiques are excellent. Others are two developers with a Notion template and a lot of confidence. Do your due diligence: ask for sample deliverables, references, and specific experience with your tech stack.
Best for
Mid-market companies ($10M-$500M revenue) with 100K-500K LOC codebases who need a real answer, not a slideshow.
Option 4: AI-Powered Automated Assessment
What it involves
Tools like our own free technical debt assessment -- and others like CodeClimate, Codacy, and SonarCloud -- analyze your codebase automatically using static analysis and, increasingly, AI reasoning to provide context beyond raw metrics.
Real cost breakdown
| Tool Type | Cost |
|---|---|
| SonarCloud (open source projects) | Free |
| CodeClimate / Codacy | $50-$300/month |
| Studio X Free Assessment | Free (upload your code, get a report) |
| AI-enhanced paid reports | $500-$5,000 per report |
What you get
Speed. A tool can analyze a 500K LOC codebase in minutes, not weeks. You get consistent, reproducible metrics -- no analyst variance. AI-powered tools go further than traditional static analysis by identifying architectural patterns, estimating refactoring effort, and generating actionable recommendations prioritized by business impact.
Our free assessment, for example, analyzes uploaded code for:
- Overall health score (graded A through F)
- Code quality, dependency health, security vulnerabilities, test coverage
- Top 10 quick wins you can act on immediately
- A prioritized modernization roadmap
- Estimated lines of code and complexity score
The limitation
Automated tools can't interview your team, understand business context, or tell you that the "messy" module that looks terrible is actually the most business-critical piece of the system that nobody should touch. They're excellent at finding what the problems are -- less useful for the why and the so what.
Best for
Getting a fast, honest baseline before committing to anything. Also excellent as a sanity check on what a consultant tells you -- run a free assessment first, then see if the consultant's findings align.
The Costs Everyone Forgets
Whatever option you choose, these indirect costs almost never appear in a proposal:
1. Internal team time
Every assessment requires cooperation from your engineers -- answering questions, providing access, reviewing findings. Budget 20-40 hours of senior engineer time regardless of which option you choose.
2. Decision latency
The longer the assessment takes, the longer your team is in limbo. Every week engineers spend waiting for "the results" is a week of slower velocity and lower morale. A 12-week assessment that produces a 6-month delay before any work starts has a real cost that doesn't appear on any invoice.
3. The cost of a wrong answer
If the assessment misses a major problem -- a critical security vulnerability, an architectural constraint that invalidates the proposed migration path -- you'll discover it mid-project. The cost of discovering a $200K problem during a migration is multiples higher than finding it during an assessment.
4. Opportunity cost of staying put
This one gets overlooked most often. Every month you spend assessing, deciding, and planning is another month your legacy system is accumulating more technical debt, slowing your team, and preventing new features from reaching customers. Companies with legacy systems report losing 30-40% of engineering capacity to maintenance, bug fixes, and workarounds. The real cost of delay is often $50,000-$200,000 per month in lost engineering productivity -- and that number doesn't appear on any consultant's invoice.
What Does a Good Assessment Actually Save You?
Here's how to frame the ROI conversation with your leadership team:
Without a proper assessment
- You discover major architectural problems 3 months into a migration -- restart cost: $200,000+
- You underestimate effort by 2x and blow your budget mid-project
- You start modernizing the wrong thing first and defer the highest-value work
- Your engineers fight fires in the legacy system throughout the project because nobody mapped the dependencies correctly
With a proper assessment
- Accurate effort estimates mean realistic budgets and timelines
- Prioritized roadmap means the first release delivers maximum business value
- Known risks mean contingency plans, not emergency pivots
- Clear scope means fewer scope creep battles with stakeholders
A $25,000 assessment that prevents a $300,000 project overrun has a 12x ROI. That math is usually compelling to any CFO -- you just have to present it.
What to Look for in Any Assessment
Regardless of which option you pursue, here's what separates a useful assessment from an expensive document:
Red flags
- The deliverable is a slide deck, not a technical document
- No one on the assessment team has hands-on experience with your specific tech stack
- The findings are all high-level observations with no specific code references
- The recommended path forward conveniently requires hiring the same firm
- There are no quantified estimates -- just "significant effort" and "moderate complexity"
Green flags
- Specific line-of-code references for identified problems
- Effort estimates in hours or story points, not vague ranges
- Honest assessment of what's working well, not just what's broken
- A prioritized list that distinguishes between urgent and important
- A migration strategy section that considers your team's current capabilities
- Clear documentation of assumptions and what was out of scope
Our Recommendation by Situation
| Your Situation | Recommended Path | Expected Cost |
|---|---|---|
| Need a quick baseline before leadership meeting | Free automated assessment | $0 |
| Small codebase, tight budget, need technical depth | Boutique technical consultancy | $5,000-$20,000 |
| Mid-market, 100K-500K LOC, serious modernization planned | Boutique consultancy with AI tooling | $20,000-$60,000 |
| Enterprise, regulatory requirements, large stakeholder group | Tier 2 consulting firm or large boutique | $60,000-$200,000 |
| Very large enterprise with budget to match | Tier 1 consulting firm | $150,000-$500,000+ |
The Bottom Line
A legacy codebase assessment is not optional -- it's the difference between a modernization project that finishes on time and one that quietly becomes a multi-year nightmare.
What you should spend depends on what you're protecting. A $500M annual revenue business running on a legacy system that could fail at any point? Spend $100,000 on the assessment and do it right. A $5M SaaS company that needs to decide whether to refactor or rebuild? Start with a free automated assessment, then engage a boutique firm for depth where you need it.
The worst choice is paralysis. Every month you delay the assessment is another month the problem gets more expensive to solve.
See What Your Codebase Is Really Worth
Our free technical debt assessment analyzes your codebase in minutes. Upload your source code, accept the NDA, and get back a full report with a health score, risk breakdown, and a prioritized list of quick wins -- completely free.
It's a good starting point for any of the paths above. At minimum, you'll walk into any consulting engagement knowing what questions to ask.
Get your free assessment -- no credit card, no commitment.
Learn more at www.studioxconsulting.com. Contact Studio X Consulting to discuss legacy modernization, AI-assisted development, and delivery.