Claude AI Is Now Inside Microsoft 365 (And It Changes Everything)

If you’ve been curious about Claude Cowork and its plugins, here’s a big one: Claude now works inside Microsoft 365 as an add-in, and it’s built a real challenger to Copilot. I tested it on the two things most of us actually use AI for in Office — Excel and PowerPoint — and I was blown away. Here’s how it compares and whether it’s worth investing in.

How It’s Set Up (and What It Costs)

One thing to clear up first: this isn’t built into Claude — it’s a Microsoft add-in, installed from the Microsoft marketplace for PowerPoint and Excel. You’ll need a paid Claude plan; whether you’re on the $20/month Pro plan or the $100/month tier, it works, though Pro has a limited number of credits, so you can’t spin up a fresh presentation every hour. On price, the Copilot add-on runs $30 a month and Claude is $20 — and for integrating with Excel and PowerPoint specifically, I’ve found Claude more capable, even though Copilot is native to Microsoft.

PowerPoint: Building a Deck From a Prompt

I asked Claude to create a presentation on smartphone trends over the last five years. With Cowork, you can also connect it to files on your desktop — point it at a folder of real data and say “turn this into a brand-compliant PowerPoint.” Copilot can build decks too, but in my experience it’s unreliable on heavier, more analytical work — you get error codes and it doesn’t perform the way it should. Claude gives you the power you’re actually paying for.

It Checks Its Own Work

The finished deck came together from just my opening prompt, and you can restyle it with themes or brand guidelines afterward. What stood out: it had a couple of overlapping elements, caught the issue itself, and went back to fix it — “let me fix a key issue where these are overlapping.” That self-checking is something Copilot doesn’t really do in my tests, and it’s a meaningful difference when the whole point of a slide is to present information cleanly.

Excel: Real Analysis, Not Just Formulas

Excel is where this got impressive. I had a sheet of website traffic data and asked Claude for a trend analysis compared to industry benchmarks. It created a separate tab, pulled metrics from across the other tabs, compared them against benchmarks it sourced online, and gave me an assessment of where I was performing above or below expectations — chart included. Copilot, in my experience, falls over on this depth of analysis, usually with errors or file issues. You can keep going too, asking follow-ups like “what recommendations would improve my traffic?” or even running a regression model.

Why This Matters

The trade-off is reach: Copilot spans all of Microsoft — Teams, Outlook, Word, Excel, PowerPoint — while Claude is currently limited to Excel and PowerPoint. But within those two, it’s more capable, and because it’s connected to your account, you can reference past work later, even from your phone. For the analytical heavy lifting, Claude inside Office is the more powerful tool right now.

Let me know if you’ve tried Claude in your own Office workflow and how it went. And if you want to see how Copilot handles Excel for comparison, check out the related video above.