How to Convert Files Between Mac and Windows: Compatibility Guide

The Cross-Platform Compatibility Problem

A designer on a Mac sends a file to a client on Windows, and the client cannot open it. A Windows user shares a video with a Mac user, and the format plays differently. A team collaborating across both platforms discovers that their documents render differently on each operating system.

Despite decades of standardization, Mac and Windows still have meaningful format differences that trip up users daily. Each platform has its own native formats, default applications, font libraries, and media codecs. These differences create friction every time files cross the platform boundary.

This guide identifies every common compatibility issue between Mac and Windows and provides specific conversion solutions for each one.

The Biggest Mac vs. Windows Format Conflicts

Documents: Pages, Numbers, Keynote vs. Office

The Problem

Apple's iWork suite (Pages, Numbers, Keynote) saves in proprietary formats that Microsoft Office cannot open. Similarly, complex Word, Excel, and PowerPoint files sometimes render differently in Apple's iWork apps.

The Solution: Universal Formats

For sharing: Always export to a universal format before sending to someone on a different platform.

From Mac (Pages/Numbers/Keynote) to Windows:

1. Open the file in the iWork app
2. Go to File > Export To > [Word/Excel/PowerPoint]
3. Choose .docx, .xlsx, or .pptx format
4. Save and send the exported file

Alternatively, export to PDF for read-only sharing. PDF is the ultimate cross-platform format -- it looks identical on every device and operating system. Use the Word to PDF converter for creating PDFs from any source document.

From Windows to Mac:

Modern iWork apps (Pages, Numbers, Keynote) can open Microsoft Office formats directly. However, complex formatting -- macros, custom fonts, embedded objects -- may not translate perfectly. For critical documents, send a PDF alongside the editable Office file so the recipient can see the intended layout.

Font Compatibility Issues

This is a subtle but frequent problem. Mac and Windows include different default fonts:

• Windows defaults: Calibri, Cambria, Arial, Times New Roman, Segoe UI
• Mac defaults: San Francisco, Helvetica Neue, Georgia, Avenir

When a document uses a font that is not installed on the recipient's system, the operating system substitutes a different font. This can cause text reflow, layout changes, and misaligned elements.

Solutions:

• Embed fonts in the document (Word supports this: File > Options > Save > Embed fonts)
• Use universal fonts available on both platforms: Arial, Times New Roman, Courier New, Georgia, Verdana
• Export to PDF, which embeds fonts automatically

Images: HEIC, TIFF, and Format Differences

HEIC: The iPhone Photo Problem

Since iOS 11 (2017), iPhones save photos in HEIC format by default. HEIC uses H.265 compression, producing files roughly half the size of JPEG at the same quality. macOS handles HEIC natively, but Windows support is inconsistent:

• Windows 10/11: Can open HEIC after installing the free "HEIF Image Extensions" from the Microsoft Store, but the "HEVC Video Extensions" (needed for full support) costs $0.99
• Windows 7/8: No HEIC support at all
• Web browsers (Windows): Cannot display HEIC in web apps
• Third-party apps (Windows): Support varies

The solution: Convert HEIC to JPEG before sharing with Windows users. Use the HEIC converter for quick conversion.

To prevent the problem at the source, change your iPhone's camera settings:

1. Go to Settings > Camera > Formats
2. Select Most Compatible (saves as JPEG instead of HEIC)

TIFF Handling

TIFF files open in Preview on Mac and in Windows Photo Viewer/Paint on Windows. However, multi-page TIFFs and TIFFs with specific compression (LZW, ZIP) may not render correctly on Windows.

Solution: For sharing, convert TIFF to PNG (lossless) or JPEG (photos). Use the image compressor for optimized output.

RAW Photo Files

Camera RAW formats (.CR2, .NEF, .ARW, .DNG) are generally supported on both platforms through their respective default photo apps, but rendering can differ. Adobe DNG (Digital Negative) is the most universal RAW format.

Video: MOV, WMV, and Codec Conflicts

MOV Files (Mac to Windows)

MOV is Apple's QuickTime container format. While modern Windows can play many MOV files through the built-in Movies & TV app, compatibility depends on the codec inside:

• MOV + H.264: Usually plays on Windows 10/11
• MOV + H.265: Requires HEVC codec on Windows (may cost $0.99)
• MOV + ProRes: Does not play on Windows without additional software

For guaranteed compatibility, convert MOV to MP4 using the MOV to MP4 converter. The how to convert MOV to MP4 guide covers the complete process.

WMV Files (Windows to Mac)

WMV (Windows Media Video) is Microsoft's proprietary format. macOS cannot play WMV natively:

• QuickTime Player: Does not support WMV
• VLC: Plays WMV on Mac (free download)
• Better solution: Convert WMV to MP4 using the MP4 converter

AVI Files

AVI is technically supported on both platforms, but compatibility depends entirely on the codecs used inside the container. Some AVI files use codecs that only work on one platform.

Solution: Convert AVI to MP4 for universal compatibility. See the AVI to MP4 guide.

FFmpeg for Cross-Platform Video Conversion

FFmpeg runs on both Mac and Windows and is the most reliable cross-platform conversion tool:

# Convert any video to universally compatible MP4
ffmpeg -i input.mov -c:v libx264 -crf 22 -preset medium -c:a aac -b:a 192k output.mp4

For those new to FFmpeg, the FFmpeg beginner's guide covers installation and usage on both platforms.

Audio: AIFF, WMA, and Codec Issues

AIFF (Mac) vs. WAV (Windows)

Both are uncompressed audio formats with identical quality. AIFF is Apple's standard; WAV is Microsoft's. In practice:

• macOS: Opens both AIFF and WAV natively
• Windows: Opens both, but WAV is native and better supported in Windows audio tools

For sharing, convert to MP3 (universal lossy) or FLAC (universal lossless):

# AIFF to MP3
ffmpeg -i input.aiff -c:a libmp3lame -b:a 192k output.mp3

# AIFF to FLAC (lossless)
ffmpeg -i input.aiff -c:a flac output.flac

Use the WAV to MP3 converter for quick audio conversion.

WMA (Windows to Mac)

WMA files do not play in any default macOS application. Convert to MP3 or AAC before sharing:

ffmpeg -i input.wma -c:a libmp3lame -b:a 192k output.mp3

Apple Lossless (ALAC) vs. FLAC

ALAC (Apple Lossless Audio Codec) and FLAC are both lossless audio formats:

• ALAC: Works natively on Apple devices, limited Windows support
• FLAC: Works on Windows, Android, Linux, and most Mac apps (but not iTunes/Apple Music without conversion)

For cross-platform lossless audio, FLAC has broader support across non-Apple platforms. For Apple-centric workflows, ALAC is the native choice.

File System and Naming Issues

Filename Character Restrictions

Mac and Windows have different rules for filenames:

Case Sensitivity

macOS uses a case-insensitive filesystem by default (APFS is case-insensitive). Windows (NTFS) is also case-insensitive. So "Photo.jpg" and "photo.jpg" are considered the same file on both platforms.

However, Linux is case-sensitive, so if your files pass through a Linux server (common in web hosting and cloud storage), "Photo.jpg" and "photo.jpg" are different files.

Hidden Files (.DS_Store, Thumbs.db)

Mac creates .DS_Store files in every folder (storing view preferences). Windows creates Thumbs.db and desktop.ini files. These are harmless but annoying when sharing folders.

Clean up before sharing:

# Remove .DS_Store files from a folder (Mac)
find /path/to/folder -name ".DS_Store" -delete

# Remove Thumbs.db files from a folder (Windows PowerShell)
Get-ChildItem -Path "C:\path" -Recurse -Filter "Thumbs.db" | Remove-Item

Line Endings in Text Files

Mac/Linux uses LF (line feed) for line endings. Windows uses CRLF (carriage return + line feed). This difference can cause issues with code, CSV files, and scripts.

Fix in most text editors: Look for line ending settings (usually in the status bar) and switch between LF and CRLF.

Fix with command line:

# Convert Windows line endings to Mac/Unix (install dos2unix)
dos2unix file.txt

# Convert Mac/Unix line endings to Windows
unix2dos file.txt

Cross-Platform Conversion Checklist

Before sharing files across platforms, run through this checklist:

Documents

• Export Pages/Numbers/Keynote to DOCX/XLSX/PPTX or PDF
• Use universal fonts (Arial, Times New Roman, Georgia)
• Embed fonts in Word documents
• Test PDF rendering on both platforms

Images

• Convert HEIC to JPEG or PNG
• Avoid TIFF for sharing (use PNG or JPEG)
• Remove macOS metadata (extended attributes) with xattr -cr file

Video

• Convert MOV to MP4 (H.264 + AAC)
• Convert WMV to MP4
• Avoid ProRes for Windows recipients

Audio

• Convert AIFF to WAV, MP3, or FLAC
• Convert WMA to MP3 or AAC
• Convert ALAC to FLAC for non-Apple recipients

Files and Folders

• Use ASCII-only filenames
• Avoid special characters and trailing spaces
• Remove .DS_Store and Thumbs.db before sharing
• ZIP folders for cross-platform transfer

The Universal Format Strategy

If you regularly share files across Mac and Windows, adopt these universal formats as your defaults:

Related Resources

• File Format Compatibility Guide -- Comprehensive cross-platform compatibility
• How to Convert MOV to MP4 -- Mac video conversion
• How to Convert AVI to MP4 -- Windows video conversion
• File Format Cheat Sheet 2026 -- Quick reference for all formats
• Data Privacy in File Conversion -- Security when using online converters

Summary

Cross-platform file sharing between Mac and Windows comes down to using universal formats: PDF for documents, JPEG/PNG for images, MP4 for video, MP3/FLAC for audio, and ZIP for archives. The most common issues -- HEIC photos, MOV videos, Pages/Numbers/Keynote documents, and WMV/WMA files -- all have straightforward conversion solutions. When both platforms need to work with the same file, always choose the format with the broadest compatibility rather than the one native to your platform.