How Much Does It Cost to Modernize Legacy Software?
Legacy modernization typically costs $30,000 to $150,000+, driven by system size, how much logic must be preserved, data migration, and whether you re-platform incrementally or rebuild. Incremental modernization usually beats a risky big-bang rewrite.
Typical cost ranges
Targeted modernization
$30k-$70k
Modernize a module or critical path; strangler-fig approach.
Re-platform
$70k-$150k
Move the core to a modern stack with data migration.
Full rebuild
$150k+
Rebuild a large system; phased to manage risk.
Typically 6-20+ weeks, usually phased.
What drives the cost
Size and complexity of the existing system
How much business logic must be preserved
Data migration volume and quality
Integrations with other systems
Incremental re-platform vs full rebuild
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Frequently asked questions
Should we rewrite everything at once?
Rarely. Incremental modernization (replace piece by piece behind a stable interface) lowers risk and delivers value sooner than a big-bang rewrite.
How do we de-risk a modernization?
Start with an audit and a phased plan: preserve critical logic, migrate data carefully, and ship in slices. The estimate produces that phased plan.