How much does PHP modernization cost?
PHP modernization projects typically cost $30,000 to $250,000 depending on codebase size, test coverage, and the depth of the upgrade. A small codebase (10-30k lines) moving from PHP 7.x to 8.x with reasonable existing tests typically takes 4-8 weeks and lands at $30k-$70k; a large codebase (100k+ lines) with limited tests and major framework upgrades (PHP 5 to 8, or Laravel 5 to 13) commonly runs 4-9 months and $150k-$400k. The honest answer requires a written audit first.
The longer answer
PHP modernization cost is driven by three factors more than any other: (1) the size of the codebase being modernized, (2) the existing test coverage, and (3) the size of the version jump. A 10,000-line codebase moving from PHP 7.4 to PHP 8.3 with 60%+ test coverage is a four-week engagement; a 200,000-line codebase moving from PHP 5.6 to PHP 8.3 with no tests is a year-long engagement.
The audit comes first
Before a fixed-price quote is meaningful, the codebase needs an audit: which framework version, what dependencies have known upper-bound conflicts, what custom code touches deprecated PHP APIs, what test coverage exists, what the deployment shape is, and what the rollback plan is. The audit itself is a $3,000-$10,000 paid deliverable that produces an itemized modernization plan with risk-graded steps.
What modernization actually involves
For a typical PHP 7 → 8 upgrade: upgrading Composer dependencies (often the longest-tail risk because some packages have abandoned upper-bound updates), fixing strict-type violations (PHP 8 is stricter about implicit casts), modernizing deprecated APIs (mysql_* → mysqli_* or PDO, ext-mcrypt → ext-sodium), updating tests to current Pest / PHPUnit, and re-baselining the deployment pipeline. The actual code changes are usually the smallest part of the work; the test re-baseline and dependency conflict resolution dominate.
What modernization does NOT involve
A modernization engagement is not a re-architecture. If the existing codebase has fundamental design problems — a monolith that should be a few well-scoped services, a database schema that fights every query, a domain model that doesn't match how the business actually works — those are separate engagements. Conflating modernization with re-architecture is the most common reason modernization budgets balloon.
Common follow-up questions
How long does PHP modernization take?
Four weeks to twelve months depending on codebase size, existing test coverage, and the size of the version jump. Most engagements land between 8 and 16 weeks.
Should I rewrite or modernize?
Modernize first; rewrite only after the modernization audit explicitly recommends it. Rewrites take 3-5x longer than modernizations and are 5-10x more likely to ship late or never. The audit is the right place to make that call.
Will modernization break my production system?
Only if it's done without a proper test baseline and rollback plan. A senior modernization engineer establishes both before changing any code. The risk profile of a senior modernization is materially lower than the risk of running unsupported PHP indefinitely.
If this answer is useful and you have a real engagement in mind, the contact form routes directly to the principal — James Henderson is the single engineer who scopes, writes, and supports every engagement end-to-end.