.MDI file extension

To open .MDI files on Windows, try opening the .MDI file with Microsoft Office Document Imaging (MODI) if it is installed (it’s the primary application associated with MDI).

To open a .MDI file, use Microsoft Office Document Imaging (MODI), which created and used the format. If you don’t have MODI available, the practical approach is to open it on a Windows PC with MODI installed or convert it to TIFF/PDF using a compatible tool or workflow.

Home Extension Index Images in index Images category page

Last updated: June 11, 2026 · Reviewed by Julian Stricker

What “reviewed” means on this page

Format fit: whether the “what is this file?” description matches common real-world use of the extension, including category, typical MIME types, and aliases.
Opening paths: whether Windows / macOS / Linux steps read plausibly for current OS dialogs and default apps; we remove fantasy menus and unsafe shortcuts.
Security framing: whether risk notes match the extension class (for example executables vs plain data) and whether affiliate wording does not contradict the security section.
Sources and further reading: whether external links point to vendors, standards bodies, or other primary references where possible; we avoid inventing details we cannot ground.
Limits: this is clarity and safety-messaging QA, not a guarantee that every statement is exhaustive or that every binary you download is harmless.

Full methodology in the Imprint — The Imprint also states where AI is used and what that does—and does not—replace.

Open on your device

Choose your operating system for a dedicated step-by-step opening guide.

How to open .MDI files

Use these platform-specific instructions to open .MDI files safely.

Windows

Try opening the .MDI file with Microsoft Office Document Imaging (MODI) if it is installed (it’s the primary application associated with MDI).
If Windows asks what to use, choose MODI in “Open with”; if you don’t have it, your best option is to open the file on a PC that has MODI available or convert it to a more common format (such as TIFF/PDF) using a compatible conversion workflow.

Full Windows guide

Mac

macOS does not commonly support .MDI files natively; if you can’t preview it, move the file to a Windows PC with Microsoft Office Document Imaging (MODI) to open or convert it.
After conversion to TIFF or PDF, open the converted file in standard macOS apps.

Full Mac guide

Linux

Linux typically won’t have built-in support for .MDI; if it doesn’t open in your viewer, transfer the file to a Windows system with MODI to open or convert it.
Once converted to TIFF/PDF, open the result with your normal Linux image/PDF viewer.

Full Linux guide

iOS

iOS usually can’t preview .MDI directly; transfer the file to a desktop (preferably Windows with MODI) to convert it to PDF/TIFF, then view the converted file on iOS.

Full iOS guide

Android

Android apps commonly can’t open .MDI directly; move the file to a desktop (preferably Windows with MODI) to convert it to PDF/TIFF, then open the converted file on Android.

Full Android guide

Security notes

.MDI is an image/document format (TIFF-based) rather than an executable, but it still relies on complex file parsing; only open unknown .MDI files in trusted, well-known software.
Be cautious with unexpected .MDI attachments: attackers can use malformed image/document files to target vulnerabilities in document imaging software. If you must inspect a suspicious file, prefer doing so on a non-critical machine and convert it to a safer, widely supported format afterward.
Avoid “renaming to .tif” as a way to open it—this can confuse software and doesn’t actually convert the file; use the proper application/workflow to open and export/convert.

Complex decoders and untrusted media

Image, audio, and video decoders are large software surfaces; issues are uncommon for everyday files but show up with crafted files from unknown sources. Keeping the OS and media apps updated matters most; scanning is reasonable extra caution for downloads you cannot vouch for.

Avast

Avast offers free and premium antivirus software that protects against viruses, malware, ransomware, and phishing. Scan files before opening them to ensure safety.

Norton

Norton 360 delivers comprehensive antivirus protection, VPN, and identity theft monitoring. Scan files for threats before opening to keep your device secure.

We may earn a commission when you use affiliate links. This supports our free file extension guides.

Can't open this file?

These are the most common causes and fixes when .MDI files fail to open.

Common reasons

Windows can’t find an app to open the .MDI file
The file opens but pages are missing or look corrupted
macOS/Linux/phone won’t preview the .MDI file

Fix steps

Check whether Microsoft Office Document Imaging (MODI) is available on the machine; it’s the most common program associated with .MDI.
If you can’t install or access MODI, use a Windows system where MODI is available to open the file and convert/export it to TIFF or PDF for broader compatibility.

OS-specific troubleshooting

What is a .MDI file?

.MDI is a proprietary Microsoft Document Imaging format used by Microsoft Office Document Imaging (MODI). Microsoft’s documentation describes it as a TIFF-based format designed to store page-layout images (often multi-page scans). The registered media type associated with this format is image/vnd.ms-modi.

Background

MDI (Microsoft Document Imaging) is primarily associated with Microsoft Office Document Imaging (MODI), a component of Microsoft Office shared tools. In real-world use, it commonly appears when older scanning or document-imaging workflows saved scans as MDI rather than TIFF.

Common MIME types: image/vnd.ms-modi

Common .MDI issues

Windows can’t find an app to open the .MDI file

This typically happens because Microsoft Office Document Imaging (MODI) isn’t installed, and MDI is not widely supported by default applications.

Check whether Microsoft Office Document Imaging (MODI) is available on the machine; it’s the most common program associated with .MDI.
If you can’t install or access MODI, use a Windows system where MODI is available to open the file and convert/export it to TIFF or PDF for broader compatibility.

The file opens but pages are missing or look corrupted

Because MDI is often used for multi-page scanned documents, incomplete transfers/downloads can show as missing pages or corrupted rendering.

Re-copy or re-download the .MDI file to ensure it transferred completely (especially if it came via email or network share).
Try opening it in Microsoft Office Document Imaging (MODI) and, if it loads, convert/export to TIFF/PDF to reduce future compatibility problems.

macOS/Linux/phone won’t preview the .MDI file

.MDI is tied to Microsoft Document Imaging and isn’t commonly supported on non-Windows platforms.

Transfer the file to Windows and open it with MODI to confirm it’s valid.
Convert it to TIFF or PDF for viewing on macOS, Linux, iOS, and Android.

FAQ

What does .MDI stand for?

MDI stands for Microsoft Document Imaging, the format used by Microsoft Office Document Imaging (MODI).

Is an .MDI file the same as TIFF?

Not exactly. Microsoft’s documentation describes MDI as TIFF-based, but it’s a proprietary format used by MODI and isn’t as widely supported as standard TIFF.

What is the MIME type for .MDI?

The registered media type associated with Microsoft Document Imaging is image/vnd.ms-modi.

Can I convert a file by renaming it to .MDI (or renaming .MDI to .TIF)?

No. Renaming only changes the extension text; it doesn’t convert the underlying file format. Use a proper open-and-export/convert workflow.

Similar file extensions

Compare related formats in the same category to find the right tool faster.