This guide breaks the cost down by workstream so operators can scope realistically and avoid the common under-budgeting traps. The numbers come from actual 2025-2026 engagements at the brand sizes named. Brands far from the median ($5M-$50M) should expect the ranges to shift; the decision structure does not.
The dominant cost is agency hours, not tool subscriptions. Tools total under $5K for typical migrations; the rest is engineering, project management, and SEO discipline. Brands that fixate on tool cost and skimp on agency selection consistently produce worse outcomes than brands that pick the right partner and accept the agency cost as the dominant line item.
By brand size
Cost ranges by brand size tier
$5M-$15M DTC brands
$60K-$110K
Under 10K SKUs, standard Magento install, single store, modest B2B exposure. Cart2Cart or LitExtension automated path with Matrixify reconciliation. Theme rebuild from a premium template.
$15M-$50M DTC brands
$110K-$220K
Up to 50K SKUs, custom Magento extensions, possible B2B Edition exposure, occasional multi-store. Same automated tooling plus more agency hours on reconciliation. Often includes iPaaS for dual-write cutover.
$50M-$200M brands
$220K-$700K+
Enterprise complexity: deep B2B Edition usage, multi-source inventory, Adobe Commerce-tier features, multi-region, complex ERP/OMS integration. Custom data work, enterprise iPaaS (Boomi or MuleSoft), substantial agency engineering resourcing.
By workstream
Cost breakdown by workstream
| Workstream | Range |
|---|---|
Discovery and planning Two to four weeks of agency discovery: redirect map build, data dictionary, app re-implementation plan, go-live runbook. Brands that compress this consistently pay later in reconciliation. | $8K-$25K |
Catalog and customer data migration Automated platform fees plus agency engineering hours for field reconciliation, custom-field mapping, and the order-history decision. Dominated by Matrixify usage and the size of the catalog being moved. | $15K-$60K |
Theme rebuild Premium template ($200-$400) plus customisation hours. Brands rebuilding from scratch (custom theme) land at the upper end; brands customising a Theme Store template land lower. Heavy content rebuild adds 10-20% to the range. | $15K-$70K |
App re-implementation Subscription app migration, loyalty re-setup, reviews import, search/filtering reconfiguration. Cost scales with the source-platform app stack count. Brands with five-plus dependent apps land near the upper end. | $8K-$30K |
SEO migration audit and operations Audit, redirect map build, validation, and eight-week post-launch monitoring. Almost always under-budgeted by brands that treat it as a checklist; consistently the difference between holding and losing organic rankings. | $8K-$40K |
iPaaS (if dual-write) Celigo for mid-market; Boomi or MuleSoft for enterprise. Only justified for genuine multi-week cutover overlap. Single-weekend cutovers skip this line entirely. | $10K-$50K annually |
Project management Agency PM hours across the engagement. Larger agencies carry higher PM overhead; boutiques carry less. Quality of PM is one of the strongest predictors of on-time delivery. | $6K-$25K |
What drives the variance
Why cost ranges vary so much
SKU count
Under 10K SKUs: low end. 10K-50K SKUs: middle. Above 50K: high end. Each tier roughly adds $20K-$40K of reconciliation work.
Custom Magento extensions in production
Each Webkul, Mageworx, or Aitoc extension that needs Shopify equivalent re-implementation adds $3K-$10K of agency hours. Five-plus extensions consistently push the engagement toward the upper bound.
B2B Edition complexity
B2B customer hierarchies, quote workflows, and price-list reconstruction add $15K-$50K. Brands with active B2B almost always land in the upper half of the cost range.
Subscription tenure
Active subscribers add $10K-$40K depending on subscriber count and billing-cycle complexity. Brands with $1M+ subscription revenue should treat this as a workstream of its own with dedicated cost line.
Order history depth
Migrating up to 24 months of orders is included in typical ranges. Five-plus years adds $5K-$25K. Most brands cap at 24 months and archive older orders in a warehouse.
Multi-store or multi-region
Each additional Shopify store target adds $15K-$40K of coordination, theme work, and data routing. Multi-region adds Shopify Markets configuration and tax handling.
Hidden costs
Cost lines operators forget to budget
Internal team time
Two to four hours per week from a product owner, ecommerce lead, and finance lead across the full 16-26 week timeline. At loaded internal rates, this is $15K-$45K of internal cost that does not appear on the agency invoice but is real.
Stabilisation engagement
Most brands extend the agency engagement four to eight weeks post-launch for monitoring, redirect-map gap closure, and incident response. Often $10K-$30K beyond the build engagement.
Change orders
Surfacing scope after discovery triggers change orders against the baseline. Brands without discovery discipline routinely absorb $10K-$50K in change-order costs that should have been in the original scope.
Tool subscriptions beyond migration
Matrixify, Easy Redirects, Rewind, and the bulk-edit tools become permanent app stack fixtures post-migration. Annual subscription cost is $2K-$5K across the typical migration toolchain — predictable but easy to forget when scoping migration cost.