Two numbers, not one

Project cost is what you pay once to get workloads across: assessment, target architecture, infrastructure as code, data migration, testing, cutover and a stabilisation period. It is usually quoted by a migration partner.

Run-rate is what AWS bills every month after go-live: compute, databases, storage, data transfer, monitoring and security services. AWS lists its prices in US dollars, and the AWS Pricing Calculator is the standard tool for modelling this figure.

A credible proposal states both, keeps them apart and explains the assumptions behind each. A step-by-step guide to AWS cloud migration costs and process, published by the AWS consultancy Devopsity, follows exactly this split and is a useful template for what a complete estimate should cover.

Reading cost when the team spans the UK and the US

The Region changes the price

AWS prices vary by Region, and the gap is large enough to matter in a business case. AWS’s own Price List data (publication dated 19 October 2026) shows the following Linux/x86 On-Demand rates for AWS Fargate, the serverless compute engine for containers:

That is roughly 15 per cent more for the same container in London. If the estimate was built in one Region and the workload will run in another, the run-rate is wrong before migration begins. Ask for the calculator export, and check the Region on every line.

Currency and tax are not the same on both sides

For UK-located accounts, AWS’s tax guidance states that AWS Europe UK Branch charges VAT on service charges unless the customer has a “special status”, such as an international organisation. VAT-registered businesses can add their tax registration number so that it appears on AWS’s VAT invoices.

In the United States, AWS states that it is registered to collect sales tax or other transaction taxes in a long list of states, and that the tax depends on the service and the tax address of each account. In both cases the calculator figure is pre-tax, so finance teams should confirm the treatment for their own entity.
Partner quotes add a third layer.

Many migration partners quote in euros, sterling or dollars depending on the client, so check which currency the contract will be invoiced in, and whether the AWS run-rate and the project fee have been converted at the same exchange rate.

Data residency can take workloads out of scope

AWS’s migration guidance lists data residency requirements as a common reason to retain an application in its current environment rather than migrate it. For a transatlantic organisation, this often means splitting the estate: some workloads go to London, some to a US Region and some stay where they are for now. Each choice changes both the cost and the schedule, so the estimate should show it explicitly.

Reading the timeline

The phases should be visible

AWS’s Migration Acceleration Program (MAP) structures large migrations into three phases: Assess, Mobilize, and Migrate & Modernize. Whether or not a project uses MAP funding, a proposal should show which work falls into each phase, what decision closes it and what it costs.

Strategy per workload drives duration

AWS defines seven migration strategies, known as the 7 Rs: retire, retain, rehost, relocate, repurchase, replatform, and refactor or re-architect. AWS’s guidance for large migrations recommends rehosting, relocating or replatforming first and modernising after the move, because refactoring during a large migration is the most complex option to manage. An estimate that assigns one strategy to the whole portfolio deserves a second look. Devopsity’s explainer on the 7 Rs of cloud migration sets out when each strategy fits and how it affects effort.

Published ranges are a sense check, not a quote

Benchmarks help to judge whether a proposal is in the right range. Devopsity publishes the following planning ranges for partner-led AWS migrations:

Devopsity’s cost breakdown of migration cost by company size also lists the factors that push a project up or down a band, such as compliance requirements, heterogeneous database migrations and zero-downtime cutovers. If a quote sits far outside these ranges, ask why. There may be a good reason, but it should be written down.

Data sits on the critical path

Servers are rarely what delays a migration. Data usually is. Two AWS services shape most schedules:

• AWS Transform MGN (formerly AWS Application Migration Service) handles rehosting with continuous block-level replication and orchestrated cutover. AWS does not charge for the first 90 days (2,160 hours) of replication per source server. After that, the rate is $0.042 per server per hour, or about $30 a month. The replication infrastructure and any test or cutover instances are billed as normal throughout.
• AWS Database Migration Service (DMS) can run a full load and then keep capturing ongoing changes from the source, a process AWS calls change data capture (CDC), so the target can be validated before cutover. AWS notes that CDC is not real-time and that replication latency varies with workload and resources, so the final sync window still needs testing. DMS is priced as on-demand replication instances, a serverless option or Database Savings Plans.

Check the tooling is current

The AWS migration toolset has changed recently. AWS Migration Hub has been closed to new customers since 7 November 2025, and AWS points new users to AWS Transform for similar capabilities. A 2026 proposal that relies on Migration Hub for a new account is a sign the plan was copied from an older template.

Where funding fits

MAP provides tools, training, partner expertise and what AWS calls “financial investments” to help offset initial migration costs. AWS reports that customers migrating legacy applications achieve an average of 31 per cent infrastructure savings. Funding levels and eligibility depend on the programme and the customer, so treat MAP as a variable to confirm, not a discount to assume. It also reduces the one-off project cost, not the monthly run-rate.

A checklist for reading any AWS migration estimate

1. 1. Are project cost and monthly run-rate shown separately?
   2. Is every run-rate line priced in the Region where the workload will actually run?
   3. Which currency will each invoice use, and how are VAT or US sales tax treated?
   4. Which workloads are retired, retained or kept in a specific country for residency reasons?
   5. Does each application have its own migration strategy?
   6. Are the largest databases, their sync method and cutover windows named?
   7. Are the phases, decision points and rollback plans visible?
   8. Is MAP funding shown as confirmed, applied for or merely possible?

Frequently asked questions

How long does an AWS migration take?

It depends on scope. Published partner ranges run from three to six weeks for a single application to between six and 18 months for large, regulated enterprise estates. The assessment phase is what turns a range into a defensible date.

Is AWS more expensive in London than in the US?

For many services, yes. Fargate compute in Europe (London), for example, is about 15 per cent dearer than in US East (N. Virginia) at current On-Demand rates. Always compare like for like in the AWS Pricing Calculator.

Does AWS charge VAT to UK customers?

Yes. For UK-located accounts, AWS Europe UK Branch charges VAT on service charges unless the customer has special status. VAT-registered businesses should add their tax registration number so it appears on AWS’s VAT invoices.
A migration estimate is only as useful as the questions asked of it. Teams that read it as two numbers, one dependency-driven timeline and a clear set of Region, tax and residency assumptions make better decisions, whichever side of the Atlantic they sit on. For organisations planning the move, an experienced partner such as Devopsity can turn these questions into a scoped, phased plan with costs attached.