What Copilot in Excel Can't Do: 9 Limits Microsoft Documents (Check Them Before You Promise Your CFO)
The short answer: Copilot in Excel has 9 limits that Microsoft documents itself. None of them is about wrong numbers. They're about scope: who gets Copilot, where it runs, which files it accepts, what IT controls and how new each feature is.
Accuracy is a separate question and I've left it out on purpose (what it gets wrong, and what to check has it). Where Microsoft publishes no number, I say so instead of guessing. (A limits page from someone who sells training. Fine. Read the limits first, then decide if you need me.)
Copilot in Excel limitations: the 9 that Microsoft documents
1If your label says Copilot Chat (Basic), there is no Copilot inside Excel
The bad news first: with Copilot Chat (Basic) you have no add-on licence and no Copilot in Excel at all. Microsoft defines 3 labels in total. M365 Copilot (Basic) gives standard access. Premium is the paid add-on. The no-access label dates from 15 April 2026, when Microsoft ended in-app Copilot for Copilot Chat users. Microsoft says availability also depends on your tenant configuration. The label guide is Is Copilot in Excel free?.
2If you have no licence, Copilot Chat fair use limits may reach Excel, and Microsoft publishes no numbers
Microsoft's Limits page, dated 31 October 2026, says fair use limits apply to some Copilot features for users without a licence. It publishes no specific numbers, and reaching one isn't an error. Message Center posts MC1536158 and MC1536163, both from 3 November 2026, cover unlicensed users in commercial tenants. MC1536158 says the limits are currently rolling out. MC1536163 says rollout starts on 9 November. Neither post nor the page names Excel. Copilot in Excel is a Copilot Chat tool, so limits there are plausible, but that's my inference, not Microsoft's statement. What does the Excel pane show at a limit? Not documented.
3Some features need a paid licence
The model picker needs a commercial Microsoft Copilot subscription or Microsoft 365 Premium. The Work data source needs a commercial subscription. Chat history needs a commercial licence, per Microsoft's August 2026 Excel post. The Basic labels include none of the 3.
4Edit mode isn't on every device
Only Windows, Mac and the web list all 3 modes. iPad lists chat and plan. iPhone and Android list chat. And edit is still rolling out on iPad and iPhone. The full table is in Copilot in Excel on Mac, Web and Desktop.
5Your Microsoft 365 setup can rule it out
Device-based licensing for Microsoft 365 Apps for enterprise rules Copilot out, per Microsoft. So does the Semi-Annual Enterprise Channel, until you switch to Current Channel or Monthly Enterprise Channel. Good news: from version 2606 (July 2026) Microsoft is merging that channel into Monthly Enterprise, so fewer devices should hit this. In a browser, third-party cookies must be enabled. The fixes live in Copilot Not Showing in Excel?.
6Some files are out of scope
Manual calculation blocks Copilot editing, because Calculation Options must be Automatic. Strict Open XML files aren't supported. Where a SharePoint site requires check-out, Copilot on Windows or Mac can't work with its files, though Excel for the web can. With a Double Key Encryption item open, Microsoft says Copilot can't be used in the app. Local files? That's a conflict: a February 2026 Insider post says they work, and a Microsoft tutorial dated 28 September 2026 says a local file can limit or disable Copilot. I can't settle that for you.
7IT can't switch it off for Excel alone, or set the fair use limits
Copilot in Excel is a Copilot Chat tool, so the admin settings for Copilot Chat apply and there's no separate switch. As for the fair use limits, Microsoft says admins can't view or adjust them.
8It was trained mostly on English
Microsoft's general list has 48 languages, German, French, Dutch and Spanish among them. But the Excel FAQ warns that Copilot learned mostly from English sources, so prompts and data in other languages may not work as well. The Data-tab Clean Data button likewise performs best in English at first.
9The newest features arrive in stages
Microsoft often ships Excel features to Insiders or Frontier before general availability, so the newest thing in a demo may not be on your screen yet. In its October 2026 post, the skill recorder is Insiders on Windows and Mac. The accounting skills are Frontier, per Microsoft's built-in skills page. Clean data and skill builder are rolling out to general availability. Microsoft adds that skill builder and recorder are subject to service capacity and usage limits.
Where Microsoft publishes no limit at all
Some limits people ask about aren't documented at all. Here's where Microsoft is silent.
- Workbook size. No file size, row or cell limit appears on Microsoft's FAQ, get-started or tips pages. One Microsoft tutorial (28 September 2026) still prints a cell limit that the FAQ no longer has, so this page quotes neither. Apart from that stale line, the one size figure is for the Data-tab Clean Data button, which works best up to 100 columns and 50,000 rows. Best, not maximum.
- How many other workbooks a single prompt can pull from. Microsoft documents retrieving data from other workbooks in OneDrive, SharePoint or on your computer. It states no count.
- What Copilot can read. Charts, pictures, hidden and protected sheets are covered in 7 questions to ask Copilot about a spreadsheet.
3 old limits Microsoft's Excel pages no longer list
Older guides repeat these 3, and Microsoft's current Excel pages don't list them.
- The data must be an Excel Table. Not on the current Excel pages. Microsoft's tutorial treats a tidy table or range with a single header row as best practice, not a rule.
- AutoSave must be on. Microsoft's Excel tips page says Copilot works in workbooks with AutoSave enabled or disabled. A Personal and Family FAQ dated 31 August 2026 still says AutoSave must be on, so Microsoft's pages conflict.
- Copilot can't use other workbooks. Microsoft's get-started page lists importing data from other Excel workbooks as a capability.
What this list leaves out on purpose
Microsoft cautions that Copilot can make mistakes, and says to avoid it for decisions in sensitive areas such as finance, legal or medical topics. That's accuracy, and it has its own pages. How to check an answer is in Copilot Agent Mode in Excel Is Now Edit Mode and in the 7 questions page.
How to use the 9 before you promise anything
This part is my method, not Microsoft's.
1If a limit is about licences, files or setup (1, 5, 6, 7), then IT can check it before anyone is told Copilot is coming
Those are yes or no questions per person and per file.
2If it's about features or devices (3, 4, 9), then promise only what's generally available on the platforms your people use
Insiders, Frontier and rolling out are not a plan.
3If it's about fair use or language (2, 8), then pilot with real people on real files and watch
Microsoft gives you no number to plan against, so measure your own in the pilot.
Questions about Copilot in Excel limitations
What are the limitations of Copilot in Excel?
Microsoft documents 9: your licence label, fair use limits for unlicensed users, features that need a paid licence, devices that lack edit mode, Microsoft 365 setup, unsupported file states, admin controls, English-first training and staged rollout of new features.
Is there a limit to how many prompts I can use in Copilot in Excel?
Microsoft publishes no number. For users without a licence it describes fair use limits on some Copilot Chat features. They vary through the day and aren't an error, but Microsoft doesn't name Excel. Plans for individuals use AI credits, with no monthly amount on the current page.
Is there a size limit for files in Copilot in Excel?
Microsoft's FAQ, get-started and tips pages state none. Test a large file before you rely on it.
Can Copilot in Excel work on any Excel file?
No. Calculation Options must be Automatic, Strict Open XML files aren't supported, and files from a SharePoint site that requires check-out don't work on Windows and Mac. If you suspect the format, save a copy as .xlsx.
Can admins turn off Copilot in Excel?
Not on its own. Microsoft says Copilot in Excel is a Copilot Chat tool and can't be turned off independently, so the Copilot Chat admin settings apply.
Know the limits before you roll it out.
I run live online Copilot workshops, hands-on, from 1.5 to 4 hours, for groups of 20 to 25 at most. Finance teams that live in Excel have their own session. Clients include Intel, Roche, EY and Amdocs.