SharePoint Server migration to SharePoint Online is the collaboration migration most enterprises defer because of the customisation tail. The technology is well-understood, the migration tools are mature, and the source data movement is straightforward. What makes the programme expensive is the decade of custom workflows, InfoPath forms, branding, web parts, and farm solutions that have accumulated since the original SharePoint deployment. This page is the 2026 cost reference for SharePoint to SharePoint Online migration with a focus on the customisation cost line items that dominate the budget.
The first decision in any SharePoint migration is to inventory what exists on the source farm and classify each item by migration complexity. The categorisation determines the cost shape of the programme.
SharePoint to SharePoint Online migration complexity by feature
| Feature | Migration complexity | Per-instance cost | Notes |
|---|---|---|---|
| Document libraries with standard content | Low | $200 to $800 per library | SPMT handles cleanly |
| Lists with standard columns | Low | $150 to $600 per list | SPMT handles cleanly |
| Sites with standard permissions | Low | $400 to $1,500 per site | Permission mapping required but tractable |
| Pages with classic web parts | Medium | $300 to $1,200 per page | Classic web parts mostly supported in Online; modern web parts preferred |
| Sites with custom branding (master pages) | Medium-High | $5,000 to $25,000 per site | Branding rebuild via SharePoint Theme or SPFx extension |
| SharePoint Designer workflows | High | $800 to $5,000 per workflow | Rewrite to Power Automate required |
| InfoPath forms | High | $2,000 to $12,000 per form | Replace with Power Apps or Lists; InfoPath end-of-life Oct 2026 |
| SharePoint Add-ins (Apps) | Medium-High | $3,000 to $20,000 per add-in | Some migrate cleanly; many need SPFx rewrite |
| Farm solutions (.NET code) | Very High | $8,000 to $300,000+ per solution | Cannot migrate; full rewrite to SPFx required |
| Custom Search vertical or scope | Medium | $2,000 to $8,000 per customisation | Replace with SharePoint Online search verticals |
| Site collection feature dependencies | Medium | $500 to $4,000 per dependency | Audit and remediate each feature dependency |
SharePoint Designer workflows are the most common customisation in mid-enterprise SharePoint estates. They were the default tool for business users and citizen developers to automate SharePoint processes for the decade after SharePoint 2010 launched. The cost in any SharePoint migration is dominated by the rewrite of these workflows to Power Automate, because SharePoint Online does not support them natively.
The conversion challenge. Power Automate is a different engine with a different action set, a different connector model, and a different error-handling approach. A SharePoint Designer workflow that updates a list item, sends an approval email, and creates a Teams message based on conditional logic translates to a Power Automate flow with three to seven actions, plus error handling, plus security context configuration, plus connector licensing considerations. The rewrite typically takes 4 to 24 hours per workflow depending on complexity.
A mid-enterprise SharePoint estate often has 100 to 500 SharePoint Designer workflows accumulated over a decade. At a blended $1,800 per workflow rewrite (including discovery, rewrite, testing, deployment, and end-user validation), the workflow rewrite cost alone lands at $180K to $900K. This is frequently the single largest line item in a SharePoint migration programme. The cost discipline that works is rationalisation: most estates have 30 to 50 percent of workflows that no one actively uses and can be retired rather than rewritten.
The workflow rationalisation rule
InfoPath was officially deprecated in 2014 and reaches end-of-life for SharePoint Online in October 2026. After end-of-life, InfoPath forms will not render in SharePoint Online and must be replaced. The replacement options: Power Apps (for full custom forms with business logic), Microsoft Lists with custom forms (for simpler scenarios), or third-party forms tools (Nintex, K2, Plumsail).
Mid-enterprise estates often have 50 to 300 InfoPath forms with associated business processes. The replacement cost per form varies widely: simple data-collection forms rebuild as Lists with custom forms for $1,000 to $3,000 each; complex multi-step business forms with workflow integration rebuild as Power Apps for $5,000 to $25,000 each. The October 2026 deadline forces the work; estates that have not started the replacement by mid-2026 face significant timeline pressure.
Farm solutions (full-trust .NET code deployed directly to the SharePoint farm) cannot migrate to SharePoint Online. The SharePoint Online security model does not permit full-trust code execution in the SharePoint application pool. Farm solutions must be rewritten as SharePoint Framework (SPFx) extensions, Power Platform components, or Azure-hosted applications integrated via the SharePoint REST APIs.
The cost varies enormously depending on what the farm solution does. A simple branding farm solution (custom master page, custom CSS) might rewrite as an SPFx Application Customizer for $5K to $20K. A line-of-business application built as a farm solution (custom timer jobs, custom event receivers, custom service applications) might require $100K to $500K+ of rebuild work. Mid-enterprise estates that grew organically often have three to fifteen farm solutions of mixed complexity, with the rebuild cost frequently exceeding $300K in total.
A representative cost build for a mid-enterprise SharePoint 2019 to SharePoint Online migration: 200 site collections (180 standard, 15 branded, 5 with farm solutions), 250 SharePoint Designer workflows (after rationalisation), 80 InfoPath forms, 12-month programme, partner-led with FastTrack support for the core data movement, ShareGate Migrate for the heavy lifting.
Worked SharePoint to SP Online cost build, 200 sites, 12 months
| Cost line | Low estimate | Typical estimate | High estimate |
|---|---|---|---|
| Assessment and customisation inventory | $35,000 | $70,000 | $150,000 |
| Workflow rationalisation (before rewrite) | $15,000 | $30,000 | $60,000 |
| ShareGate Migrate licensing (12 months) | $25,000 | $60,000 | $100,000 |
| Site collection migration labour (200 sites) | $80,000 | $180,000 | $420,000 |
| Branding remediation (15 branded sites) | $60,000 | $160,000 | $380,000 |
| Farm solution rewrite (5 solutions, mixed complexity) | $100,000 | $280,000 | $700,000 |
| SharePoint Designer workflow rewrite (150 after rationalisation) | $120,000 | $280,000 | $640,000 |
| InfoPath form replacement (80 forms) | $120,000 | $320,000 | $800,000 |
| FastTrack value (Microsoft-funded) | ($25,000) | ($45,000) | ($80,000) |
| End-user training and adoption | $15,000 | $35,000 | $80,000 |
| Cutover support and hypercare (6 weeks) | $25,000 | $55,000 | $120,000 |
| Source SharePoint decommission | $15,000 | $30,000 | $70,000 |
| Contingency at 15 percent | $90,000 | $220,000 | $520,000 |
| Net total estimate | $675,000 | $1,675,000 | $3,960,000 |
The typical-column number, $1.675M for 200 sites over 12 months, works out at roughly $8,400 per site collection all-in. That is significantly higher than the per-site headline band because the cost is dominated not by sites but by customisations: workflows ($280K), forms ($320K), farm solutions ($280K), and branding ($160K) together account for over $1M of the total. The cost discipline for SharePoint migration is almost always about customisation rationalisation before rewrite.
SharePoint Server to SharePoint Online migration is dominated by customisation rather than by data. The teams that succeed at SharePoint migration cost are the ones that treat the customisation rationalisation as the project, with the data movement as the easier follow-on. The October 2026 InfoPath deadline adds urgency to the timeline. The discipline that produces an on-budget outcome is rigorous customisation inventory at assessment, aggressive rationalisation before rewrite, and disciplined use of modern out-of-the-box SharePoint Online features rather than recreating the source customisation surface verbatim.
A. Mid-enterprise SharePoint migrations of 100 to 500 site collections typically cost $150,000 to $800,000 all-in. The cost per site collection ranges from $400 for a simple document library to $8,000+ for a heavily customised site with workflows, web parts, and InfoPath forms. The dominant cost drivers are custom code remediation, SharePoint Designer workflow rewrite to Power Automate, and InfoPath form replacement.
A. SharePoint Online no longer supports SharePoint Designer workflows. They must be rewritten as Power Automate flows. The conversion is rarely one-to-one because the two engines have different action sets, different connector models, and different error-handling patterns. A typical SharePoint Designer workflow takes 4 to 24 hours to rewrite in Power Automate depending on complexity. Mid-enterprise estates often have 100 to 500 SharePoint Designer workflows accumulated over a decade.
A. InfoPath was officially deprecated in 2014 and reaches full end-of-life in October 2026 for SharePoint Online. InfoPath forms must be replaced with Power Apps (for new forms) or Microsoft Lists with custom forms (for simpler scenarios). The replacement cost is typically $2,000 to $12,000 per form depending on complexity. Mid-enterprise estates often have 50 to 300 InfoPath forms with associated business processes.
A. Farm solutions (full-trust .NET code deployed to the SharePoint farm) cannot migrate to SharePoint Online. They must be rewritten as SharePoint Framework (SPFx) extensions or Power Platform components. Sandbox solutions and SharePoint Add-ins migrate with minimal change but the model is being phased out. The cost of replacing farm solutions varies enormously: simple branding solutions might rewrite as SPFx for $5K to $20K; complex business applications can require $50K to $300K+ of rebuild work.
A. Microsoft's SharePoint Migration Tool (SPMT) handles core content and basic permissions for SharePoint 2013, 2016, 2019, and Subscription Edition sources. For SharePoint 2010 sources, third-party tools (Quest Metalogix Content Matrix, AvePoint Fly, ShareGate Migrate) are usually required. ShareGate Migrate is the dominant choice for mid-enterprise SharePoint to SharePoint migrations because of its strength in customisation discovery and permission scenarios.
A. Small migrations of under 20 site collections complete in 8 to 16 weeks. Mid-enterprise migrations of 100 to 500 site collections take 6 to 18 months. Large enterprise migrations of 1,000+ site collections run 12 to 30 months. The timeline is dominated by customisation discovery and remediation, not data movement. Site collections themselves can migrate in hours; the workflow rewrites and form rebuilds take months.
Updated 2 May 2026