For a UK enterprise with 1,000 or more seats, the suite you already run decides more than the sticker price. Microsoft 365 Copilot costs £23.10 a seat a month on top of a qualifying Microsoft 365 subscription, most commonly E3 or E5 at enterprise scale, for an all-in floor of £56.60 to £74.70. Google Gemini Enterprise Standard or Plus lists at $30 a seat, needs no underlying Google Workspace subscription, but self-serve buying stops at 25 seats and invoiced buying at 1,000.
Key pointers
- Microsoft 365 Copilot is always an add-on: budget £23.10 a seat a month on top of a qualifying base licence, most commonly Microsoft 365 E3 (£33.50) or E5 (£51.60) at enterprise scale, both ex VAT.
- Google's Gemini Enterprise Business edition stops at 300 seats; a 1,000-seat rollout needs Standard or Plus, officially priced from $30 a seat a month.
- Gemini Enterprise does not require a Google Workspace subscription at all. It is a separate Google Cloud product that connects to Microsoft 365, Workspace, HubSpot and Jira alike.
- At exactly 1,000 seats you sit on Google's own invoiced-account ceiling for console purchases. Get your account team's confirmation in writing before you commit to that headcount.
- Neither vendor trains its foundation models on your prompts or your organisation's content, according to both companies' own published statements.
- Copilot only surfaces what a signed-in user can already see in Microsoft Graph. Gemini Enterprise applies the same rule through each connected system's own permissions.
- A UK-only processing region exists for Gemini Enterprise Standard and Plus, but it is allowlisted rather than self-serve. Ask before you assume it is switched on.
- Treat every figure here as a list price. Enterprise agreements at this seat count are almost always negotiated down from both vendors' published rates.
Standardising on One AI Assistant at Enterprise Scale
An IT director sitting on 1,000 or more Microsoft 365 or Google Workspace seats is not choosing a chatbot. They are choosing which company's AI reads their organisation's documents, email and chat history by default, and how much that costs once every seat is licensed. The two products the market actually compares at this scale are Microsoft 365 Copilot, Microsoft's assistant built into Word, Excel, Outlook and Teams, and Gemini Enterprise, Google's standalone agent and search platform launched in October 2025 under the Google Cloud brand rather than the Workspace brand.
That second point catches people out. Google also sells Gemini bundled into ordinary Workspace subscriptions at no separate charge, and a specialist enterprise-IT comparison flags that this is a genuinely different product from Gemini Enterprise, with no shared memory or context between the two. If your procurement brief says Gemini Enterprise, as this question does, you are pricing the Google Cloud agent platform, not the free assistant already sitting inside Gmail and Docs.
For a workforce this size, the buying decision has two load-bearing variables: what a seat costs once every dependency is counted, and what each product is allowed to see and do with your organisation's data. Everything else, from agent-building tools to UK data residency, follows from those two answers.
UK Data Protection and Data Residency
Both vendors publish specific commitments rather than vague reassurance, and they are not identical. Microsoft states that Copilot is covered by its EU Data Boundary, which keeps in-scope processing and storage within the EU for customers who rely on it, alongside its existing GDPR commitments to Microsoft 365 commercial customers.
Google's equivalent control for Gemini Enterprise Standard and Plus is a set of named regions: an EU multi-region, a US multi-region, and a small group of allowlisted in-country regions that includes the United Kingdom, listed in Google's own documentation as `europe-west2`. The distinction that matters for a UK buyer is that the UK region is not switched on by default. Google's documentation describes in-country regions as "GA with allowlist" and instructs customers to contact their Google account team for access; the default recommendation, absent a specific reason to pin data to the UK or EU, is Google's global location.
Neither of these facts settles a UK organisation's data protection obligations on its own. Where you need a specific processing location, a data processing agreement or a transfer impact assessment, that depends on your own regulatory position, your sector and the categories of personal data involved. This is not legal advice; consult your legal counsel.
How Each Assistant Reaches Your Data
Copilot works by grounding a large language model in Microsoft Graph, the index Microsoft already builds from your tenant's documents, email, calendar, meetings and chats. Microsoft's own documentation is explicit that "Copilot only surfaces organizational data to which individual users have at least view permissions," using the same SharePoint and Microsoft 365 permission model that already governs who can open a file. Nothing new is exposed; Copilot simply searches faster and writes summaries across whatever a signed-in user could already reach.
Gemini Enterprise takes a connector-based approach instead. It is not tied to any one productivity suite. It securely connects to Google Workspace, Microsoft 365, SharePoint, HubSpot, Jira and other systems, and reads each one through that system's own access controls rather than a Google-specific permission layer. That is what lets it index Microsoft 365 content for a Workspace-based buyer, or the reverse, without requiring the reader to migrate suites first.
On the training question, both vendors say the same thing in different words. Microsoft states that prompts, responses and the Microsoft Graph data behind them "aren't used to train foundation LLMs, including those used by Microsoft Copilot." Google states more broadly that Gemini Enterprise customer data, "including prompts, outputs, and training, isn't used to train Google models or models for any other customer," and that Google "never sells customer data to third parties" or "uses customer data for advertising." Treat both as the vendor's own commitment rather than an independently audited fact, and check the current wording of your own contract before you rely on it.
Pricing and Cost Model
Microsoft charges for Copilot as an add-on, never as a standalone product. Its enterprise page states plainly that "a qualifying Microsoft 365 subscription is required to purchase Copilot," and Microsoft's licensing guide lists dozens of eligible base plans, from Exchange and SharePoint tiers up to the full Microsoft 365 suites. For an enterprise-scale rollout the two realistic choices are Microsoft 365 E3 and E5. At UK list prices, paid yearly and excluding VAT, that gives three fixed numbers: the Copilot add-on at £23.10 a seat a month, Microsoft 365 E3 at £33.50, and Microsoft 365 E5 at £51.60. Add the add-on to whichever base licence you hold and the all-in floor is £56.60 a seat a month on E3, or £74.70 a seat a month on E5. Multiply either by 12 months and 1,000 seats and you get roughly £679,200 a year on the E3 route, or £896,400 a year on the E5 route, both before VAT and before any enterprise agreement discount.
Google prices Gemini Enterprise differently. There is no underlying suite requirement at all: the Business edition, at $21 a seat a month, is aimed at organisations up to 300 seats, which rules it out for a 1,000-seat rollout outright. The Standard and Plus editions, the ones with unlimited seats, are officially "Starting at $30 USD per seat per month." Google publishes that figure globally in US dollars; unlike Microsoft's UK page, there is no separate sterling list price to quote. Converting for budgeting purposes only, at an exchange rate of $1.3394 to the pound as quoted by Investing.com on 18 September 2026, $30 works out to roughly £22.40 a seat a month. That is an estimate for planning, not Google's UK price; your actual invoice will be in whatever currency your Google Cloud account is billed in, and a 1,000-seat deployment of this size should expect a negotiated rate rather than the list figure.
Seat-buying mechanics change the picture further. Google's own licensing documentation caps a self-serve or resold Cloud Billing account at 25 seats when buying through the console, and an invoiced account at 1,000 seats. A UK enterprise ordering exactly 1,000 seats is at that ceiling; the next seat requires contacting a Google Cloud sales representative or account manager for an offline order or an allowlist exemption. Microsoft's Copilot add-on carries no published seat cap of its own at enterprise level, though every seat still needs its own E3 or E5 base licence purchased alongside it.
| Item | Microsoft 365 Copilot route | Google Gemini Enterprise route |
|---|---|---|
| Assistant, per seat per month | £23.10 paid yearly, £24.26 paid monthly, ex VAT | $30.00 (Standard/Plus); no published UK sterling price |
| Underlying suite required | Microsoft 365 E3 (£33.50) or E5 (£51.60) per seat per month, ex VAT | None; works with Microsoft 365, Google Workspace or neither |
| All-in floor, per seat per month | £56.60 (E3 route) or £74.70 (E5 route), ex VAT | About £22.40, converted at $1.3394 to the pound, 18 September 2026 |
| Seats without a sales call | No published cap on the add-on itself | 25, self-serve Cloud Billing account only |
| Seats on an invoiced account | No published cap | 1,000; above that, contact your Google Cloud account team |
| Billing currency published for the UK | GBP, ex VAT, on microsoft.com/en-gb | USD, globally; a GBP rate is set by your account team |
Vendor and Option Comparison
| Criterion | Microsoft 365 Copilot | Google Gemini Enterprise |
|---|---|---|
| Where it reads from | Microsoft Graph: your Word, Excel, Outlook, Teams and SharePoint content, honouring existing permissions | Connectors to Google Workspace, Microsoft 365, SharePoint, HubSpot, Jira and others, honouring the connected system's own permissions |
| Model training on your data | No, per Microsoft's published statement | No, per Google's published statement |
| Edition for a 1,000-seat rollout | The single enterprise Copilot add-on, no edition tiers | Standard or Plus; Business tops out at 300 seats |
| Seat ceiling to plan around | None published on the add-on | 25 self-serve, 1,000 invoiced, before a sales conversation |
| UK or EU data location | EU Data Boundary for in-scope processing | Allowlisted UK region (europe-west2), plus EU and US multi-regions |
| Agent building | Copilot Studio and the in-app Agent Builder | No-code Workflow Builder on every edition; Standard and Plus add the Agent Development Kit and third-party agents |
| Best fit | Organisations already living in Word, Excel, Outlook and Teams | Organisations wanting one agent platform to search and act across Microsoft 365, Workspace and other systems at once |
Neither product wins outright. Copilot's advantage is depth inside a Microsoft 365 estate: it grounds in the same Graph your organisation already indexes, and there is no separate connector to configure for Word, Excel or Outlook. Its constraint is cost stacking; you are always paying for a base Microsoft 365 licence and the Copilot add-on together, and at 1,000 seats that is a six-figure annual commitment before you have licensed a single agent.
Gemini Enterprise's advantage is that it is suite-agnostic. A Microsoft 365 shop can buy it purely to get Google's search and agent tooling across Microsoft's own content, without paying for Google Workspace it does not use. Its constraint is the buying process at this exact seat count. A 1,000-seat order sits on Google's own invoiced-account ceiling, and the UK data region is not available without asking, so treat the self-serve list price as a starting point for a sales conversation rather than a number you can check out with.
A mixed estate, part Microsoft 365 and part Google Workspace, does not have to pick one company-wide. Piloting both against a handful of the same job roles, and comparing what each one actually surfaces from your real content, will tell you more than either vendor's list price.
Editorial Analysis
Editorial analysis: the two products are not really substitutes for the same job. Copilot is a productivity feature bolted onto a suite you are already renewing; its cost is largely the cost of upgrading that renewal. Gemini Enterprise is a search and agent layer sold independently of any suite, which is why Google can undercut Microsoft's all-in floor price while still needing a sales conversation to actually complete a 1,000-seat order. For a UK enterprise standardising on one assistant, the more useful question is not which one is cheaper on paper, but whether the job is "make my existing Microsoft 365 estate faster" or "search and act across everything, regardless of which suite it sits in." Answer that first, and the pricing comparison mostly resolves itself.
Sources
- Microsoft, AI for Enterprise Productivity, Microsoft 365 Copilot (UK pricing)
- Microsoft, Microsoft 365 Enterprise, Compare Plans and Pricing
- Microsoft Learn, Data, Privacy, and Security for Microsoft Copilot
- Microsoft Learn, License Options for Microsoft Copilot
- Google Cloud, Gemini Enterprise app editions and pricing
- Google Cloud, Get subscriptions and assign licenses for Gemini Enterprise
- Google Cloud, Data residency for Gemini Enterprise Standard and Plus Editions
- Investing.com, GBP/USD exchange rate, 18 September 2026
- Enterprise Techie, Copilot vs. Gemini Enterprise: The 2026 Rollout Decision
