Why Is My File Size Increasing?

Updated December 2025 • 6 min read

Files grow unexpectedly due to accumulated revision history, embedded preview images, uncompressed content, hidden metadata, duplicate resources, and inefficient save operations. Understanding why files bloat helps you maintain manageable file sizes and optimize storage usage.

Quick Fix: Most file bloat comes from revision history and embedded resources. Export a fresh copy of the document instead of repeatedly saving over the original. Use "Save As" or "Export" to create a clean version without accumulated cruft.

Top 10 Causes of File Size Growth

1. Revision History and Track Changes

The #1 culprit for document bloat. Microsoft Office, Google Docs, and other editors store revision history allowing you to undo changes or view document history. This metadata accumulates with every edit.

How revision history grows:

  • Every delete operation is stored (text not actually removed)
  • Multiple authors working on document = more tracked changes
  • Accepted changes still stored in file until purged
  • Moving paragraphs stores both old and new positions
  • Formatting changes tracked for each character

A 50 KB document can grow to 5 MB after extensive collaborative editing with Track Changes enabled. The visible content remains small, but hidden revision data balloons the file.

Remove Revision History:

Microsoft Word:

  1. Click Review tab
  2. Click Accept → Accept All Changes and Stop Tracking
  3. Go to File → Info → Check for Issues
  4. Select Inspect Document
  5. Check Document Properties and Personal Information
  6. Click Remove All
  7. Save document

Google Docs:

  1. Go to File → Version history
  2. Click See version history
  3. Select versions to delete (limited capability)
  4. Or create new copy: File → Make a copy (doesn't carry full history)

2. Embedded High-Resolution Images

Inserting unoptimized images dramatically increases file size. A 5 MB photo embedded in a 10 KB document creates a 5+ MB file.

Image bloat factors:

  • Inserting original camera photos (often 8-20 MB each)
  • Pasting screenshots at full resolution
  • Not compressing images before insertion
  • Using PNG for photos instead of JPEG
  • Embedding images multiple times (each copy stored separately)

Optimize Images in Documents:

Microsoft Office:

  1. Select an image in document
  2. Go to Picture Format tab
  3. Click Compress Pictures
  4. Check Apply only to this picture (or leave unchecked for all)
  5. Select resolution: Email (96 ppi) for screen, Print (220 ppi) for printing
  6. Check Delete cropped areas of pictures
  7. Click OK

Before Inserting:

  • Resize images to display dimensions (not larger)
  • Compress photos to 150-300 DPI using image editor
  • Save photos as JPEG, diagrams as PNG
  • Use image converters to optimize

3. Hidden Embedded Objects

Documents can contain hidden embedded objects: Excel spreadsheets in Word, original Photoshop files in presentations, full-resolution images behind cropped versions.

Common embedded bloat:

  • Excel charts embedding entire spreadsheet (hundreds of KB for small chart)
  • Embedded fonts (50-500 KB per font family)
  • OLE objects (full Excel/Visio files embedded)
  • PDF pages containing vector data even if displayed as image
  • Audio/video files in presentations

4. Metadata and Document Properties

Files store extensive metadata: author names, creation/edit timestamps, comments, company information, file paths, printer settings, and more.

Types of metadata:

  • EXIF data: Camera settings, GPS coordinates in photos
  • Document properties: Title, subject, keywords, author, company
  • Comments and annotations: Review comments, highlights, notes
  • Custom XML data: Application-specific information
  • File system attributes: Creation dates, modification history

Remove Metadata:

Windows:

  1. Right-click file → Properties
  2. Go to Details tab
  3. Click Remove Properties and Personal Information
  4. Select Remove the following properties
  5. Check items to remove
  6. Click OK

Mac:

  1. Use Preview to open image
  2. Go to Tools → Show Inspector
  3. View and optionally remove GPS/EXIF data

Command Line (ExifTool):

exiftool -all= image.jpg

5. Lossy Compression Accumulation

Repeatedly saving JPEG images or re-encoding videos causes generational loss. Each save cycle adds compression artifacts while paradoxically sometimes increasing file size due to artifact complexity.

Generation loss examples:

  • Opening JPEG in Photoshop, editing, saving as JPEG repeatedly
  • Re-encoding video multiple times
  • Converting between lossy formats (MP3 → OGG → MP3)
  • Copying and pasting images between documents (may re-compress)

6. Unoptimized File Format

Some formats are inherently inefficient or uncompressed. Choosing the wrong format wastes space.

Format efficiency comparison:

  • BMP vs JPEG: BMP can be 10-20x larger for photos
  • TIFF vs JPEG: Uncompressed TIFF 5-10x larger
  • WAV vs MP3: WAV 10x larger than 320kbps MP3
  • AVI vs MP4: AVI with old codecs much larger
  • DOCX vs DOC: DOCX usually 50-75% smaller (compressed XML)

Convert to Efficient Formats:

  • Photos: Use JPEG (not PNG/BMP) at 70-85% quality
  • Graphics/logos: Use PNG or SVG (not BMP)
  • Audio: MP3 320kbps or AAC for music
  • Video: MP4 with H.264 or H.265 codec
  • Documents: Modern formats (DOCX, not DOC)

7. Duplicate Content

Copy-pasting content creates duplicates. While you see one logo, the file might store it 20 times.

Duplication sources:

  • Same image inserted multiple times (each a separate copy)
  • Repeated text blocks (not always deduplicated)
  • Multiple versions of same embedded file
  • Copying styles creates duplicate style definitions

8. Undo/Redo Buffers

Active editing sessions maintain undo history in memory and sometimes in the file itself. Long editing sessions accumulate undo data.

Solution: Close and reopen files after major editing. Clears undo buffer and often reduces file size on next save.

9. Preview/Thumbnail Generation

Some formats embed preview images or thumbnails for faster display.

Preview bloat:

  • PDFs with thumbnail previews for each page
  • RAW photos with embedded JPEG previews
  • PSD files with compatibility layer
  • Video files with poster frames

Optimize PDF Previews:

  1. Open in Adobe Acrobat (not Reader)
  2. Go to File → Save As Other → Optimized PDF
  3. Click Discard Objects
  4. Check Discard embedded thumbnails
  5. Check Discard embedded search index
  6. Click OK and save

10. Incremental Save Operations

Some software uses incremental saves that append changes rather than rewriting the entire file. This speeds up saving but gradually bloats files.

Affected formats:

  • PDF files (especially with annotations)
  • Some database formats
  • Layered image files (PSD, XCF)
  • Complex spreadsheets

Solution: Use "Save As" or "Export" instead of "Save" periodically to create optimized copy.

File Type Specific Solutions

Microsoft Word/PowerPoint/Excel

Reduce Office File Sizes:

  1. Compress all images: Select any image → Picture Format → Compress Pictures → Apply to all images
  2. Remove personal info: File → Info → Check for Issues → Inspect Document
  3. Accept all tracked changes: Review → Accept All Changes
  4. Disable embedding fonts: File → Options → Save → Uncheck "Embed fonts"
  5. Link instead of embed: For large Excel charts, link to external file instead of embedding
  6. Save as new file: File → Save As (creates fresh copy without accumulated cruft)

PDF Files

PDFs accumulate annotations, forms data, and incremental updates. See our detailed guide: Why Is My PDF So Large?

Optimize PDFs:

  • Use Adobe Acrobat's "Optimize PDF" feature
  • Compress images within PDF to 150 DPI
  • Remove bookmarks, thumbnails, annotations if not needed
  • Flatten form fields after completion
  • Use online tools like SmallPDF for compression

Photoshop PSD Files

Reduce PSD Size:

  1. Flatten when possible: Layer → Flatten Image (removes all layers)
  2. Merge unnecessary layers: Combine similar layers
  3. Disable compatibility: File → Preferences → File Handling → Uncheck "Maximize Compatibility"
  4. Delete hidden layers: Remove invisible layers you don't need
  5. Reduce image resolution: Image → Image Size (if working file too large)
  6. Save copy without layers: File → Save As → TIFF with layers, or flatten to JPEG

Video Files

Video bloat causes:

  • Uncompressed or lossless codecs
  • Unnecessarily high bitrate
  • Large resolution (4K when 1080p sufficient)
  • High frame rate (60fps when 30fps adequate)

Compress Videos:

  • Handbrake (free): Re-encode with H.264 or H.265
  • FFmpeg: ffmpeg -i input.mp4 -c:v libx264 -crf 23 output.mp4
  • Reduce resolution: 4K → 1080p saves 75% space
  • Lower bitrate: 8 Mbps usually sufficient for 1080p
  • Use modern codecs: H.265 (HEVC) 50% smaller than H.264

Audio Files

Uncompressed WAV/AIFF files are 10x larger than equivalent MP3/AAC.

Reduce Audio Size:

  • Convert WAV/AIFF to MP3 320kbps (near-lossless quality)
  • Use AAC for better quality at same bitrate
  • Reduce to 192kbps for podcasts/voice recordings
  • Use Audacity for free conversion and editing
  • Trim silence from beginning/end

Monitoring File Size Growth

Check Current File Size

  • Windows: Right-click → Properties → Size
  • Mac: Right-click → Get Info → Size
  • Command line: ls -lh filename (Unix/Mac) or dir filename (Windows)

Track Size Over Time

If file grows unexpectedly:

  • Compare current size to original/backup
  • Check version history for size jumps
  • Use Document Inspector to see what's consuming space
  • Extract contents (rename .docx to .zip) to inspect individual components

Prevention Strategies

Best Practices

  • Optimize before inserting: Compress images/media before adding to documents
  • Use "Save As" periodically: Creates fresh copy without accumulated bloat
  • Accept changes promptly: Don't let Track Changes accumulate indefinitely
  • Link large objects: Link to external files instead of embedding when possible
  • Choose efficient formats: Use compressed formats appropriate for content type
  • Clean up regularly: Remove unused resources, hidden objects, outdated revisions
  • Disable auto-save temporarily: For heavy editing, disable auto-save and save manually after major changes

Automated Tools

  • NXPowerLite: Automatically compresses Office files
  • PDF Compressor: Batch PDF optimization
  • ImageOptim (Mac): Lossless image optimization
  • FileOptimizer (Windows): Multi-format file size reduction

Pro Tip

For documents that will be edited extensively over time, establish a "clean copy" workflow: Keep a master version with full history, but create fresh "save as" copies for distribution every few weeks. This prevents bloat in files sent to clients while maintaining internal revision history where it matters.

When File Size Doesn't Matter

Sometimes maintaining larger files is justified:

  • Master files: Keep uncompressed originals for archival
  • Active projects: Layers and history useful during editing
  • Legal documents: Revision history may be legally required
  • Professional printing: High-resolution uncompressed needed

Always maintain high-quality originals separately from compressed distribution copies.

Related Resources

Why Is My PDF So Large? Why Does My Image Look Blurry? File Format Converters