Running Two Versions of Excel Side by Side

People keep two versions of Excel on one PC for good reasons: a macro that only runs in the old one, a client who still sends files saved by it, or a certification exam that targets a particular release. It can be done, but the rules have tightened over the years and a few of them will bite you.

The rules that matter

• Install the oldest version first, newest last. Installing an older Office over a newer one reliably breaks file associations and shared components.
• Never install two versions into the same folder. During setup choose the custom or “Keep existing version” option so each release gets its own Program Files\Microsoft Office\OfficeNN directory.
• Do not mix 32-bit and 64-bit Office on the same machine. Windows will not allow it, and it is the single most common reason a side-by-side install refuses to proceed.
• Microsoft 365 is the awkward one. It installs with Click-to-Run rather than the traditional installer, and Microsoft’s guidance is that Click-to-Run and MSI versions of Office should not coexist. Where a combination is unsupported, expect repair prompts on every launch rather than a clean failure.

Expect the “configuring” delay

The classic symptom of a side-by-side install is Excel running a configuration step each time you switch versions, because whichever copy you open re-registers itself. It is harmless, but it adds several seconds to every launch and it annoys people quickly. Setting file associations explicitly to one version reduces how often it happens.

The alternative worth considering first

For most of the reasons people want two versions, a virtual machine is now the cleaner answer: the old Excel is fully isolated, nothing re-registers, and you can throw the machine away when the dependency finally dies. Keep a genuine side-by-side install for the case where you need both versions open at once on the same desktop.

Note that Excel 2013 reached the end of Microsoft support in April 2023, and Excel 2016 and 2019 are on their own end-of-support timelines. Running an unsupported release connected to the internet carries a security cost that is worth weighing against the convenience.

Which combinations actually work

The practical picture, from most to least trouble-free:

• Two MSI versions (2013 and 2016, say) — the traditional case, and the one the oldest-first rule was written for. Generally fine.
• An MSI version plus Microsoft 365 — install the MSI release first, 365 afterwards. Workable, but the configuration delay is at its most persistent here.
• Two Click-to-Run versions — for example 365 alongside a Click-to-Run 2019. Microsoft does not support this and the second install typically removes the first rather than sitting beside it.

Check which kind you have before starting: File → Account. “Microsoft 365” or an “Update Options” button means Click-to-Run. No update controls means MSI.

Pinning file associations

Once both are installed, decide which version owns .xlsx and .xlsm: Windows Settings → Apps → Default apps → Choose defaults by file type. Set every Excel extension to the same version, including .csv, which is easy to overlook and is often the one that triggers the configuration screen.

To open a file in the other version, launch that Excel first from its own executable and use File → Open from inside it. Double-clicking always hands the file to whichever version owns the association.

What breaks even when the install succeeds

Add-ins register per version. An add-in installed for one Excel will not appear in the other, and some installers overwrite the shared registration rather than adding a second one. Re-install add-ins after the second Excel is in place.

Power Query and Power Pivot differ between releases. A model built in a newer version may open with missing functions in the older one, without a clear error explaining why.

VBA references point at specific library versions. A macro workbook that moves between the two can pick up a MISSING reference, which fails at the first line of code rather than at the line that actually needs the library. Tools → References in the VBA editor shows it.

That last one is worth weighing if your reason for the old version was a macro in the first place: testing VBA across two Excels on one machine is exactly where a virtual machine saves you the most grief.

If your reason for keeping an old version is an exam, check first which release it targets: Microsoft’s current MOS exams (MO-210 and MO-211) are built on the Microsoft 365 version of Excel. See our Excel certifications comparison.