How to Compress a Word Document (and Why DOCX Files Get So Big)
How to Compress a Word Document
Words are essentially free. A 200-page manuscript with no images is a few hundred kilobytes, because plain text compresses extraordinarily well and .docx already applies ZIP compression to its own markup.
So when a Word document is 40 MB, the text is not the problem. Something else is in there, and the fastest way to compress a Word document is to find out what before you start changing settings.
Look Inside the File First
Like .pptx and .xlsx, a .docx file is a ZIP archive. You can open it and see exactly what is taking up space.
- Duplicate the document. Work on the copy.
- Rename it from
report.docxtoreport.zip. - Expand it.
- Open
word/media/.
Every embedded image, chart, and object is in that folder at its true size. Sort by size and the answer is usually immediate — three photographs at 9 MB each, or a single pasted chart stored as a 15 MB metafile.
This matters because the fixes below are not interchangeable. If your bloat is revision history, compressing images achieves nothing. If it is one enormous pasted object, running a document-wide picture compression will degrade every figure to solve a problem that lives in one place.
Cause 1: Images at Full Camera Resolution
Word stores what you give it. Insert a 24-megapixel photo to display at 4 inches wide and Word keeps all 24 megapixels.
Compressing images inside Word
- Click any image.
- Picture Format tab → Compress Pictures.
- Uncheck "Apply only to this picture".
- Tick Delete cropped areas of pictures.
- Choose a target resolution.
Pick the resolution by destination, not by instinct:
| Destination | Resolution |
|---|---|
| On-screen reading only | 150 ppi |
| Office printing | 220 ppi |
| Professional print | Do not compress |
| Email, size is critical | 96 ppi |
On macOS, File > Reduce File Size provides the document-wide version of this.
The catch
Word's compressor applies one setting to every image, and re-encodes as JPEG. That is reasonable for photographs and actively bad for screenshots, diagrams, and charts — JPEG produces ringing artifacts around the sharp edges of text and lines, which is exactly what technical documents are full of.
If your document is mostly screenshots, compress them individually beforehand as PNG or WebP instead. Our guide on compressing images without losing quality covers picking the right format per image type, and batch image compression handles documents with dozens of figures.
Cause 2: Cropped Images Still Carrying Their Full Data
Cropping in Word is non-destructive by default: the hidden pixels stay in the file so you can un-crop later.
Crop a 10 MB photo to a small detail and the document still carries 10 MB.
The Delete cropped areas of pictures checkbox fixes this, and it is worth running even if you leave the resolution at maximum quality — it removes data you genuinely cannot see without touching what you can.
Cause 3: Pasted Content From Other Office Apps
This one is under-appreciated and often the single largest offender.
When you copy a chart from Excel or a diagram from PowerPoint and paste it into Word, the default paste often embeds it as a vector metafile (EMF/WMF) — sometimes alongside a bitmap fallback, and sometimes with the entire source object attached so it stays editable.
A modest Excel chart can land as a multi-megabyte object. Do it fifteen times across a report and you have added a great deal of weight to display fifteen simple charts.
Fix: use Paste Special and choose Picture (PNG) or Picture (Enhanced Metafile) rather than the default. You lose the ability to edit the chart inside Word — which, for a finished report, you almost certainly do not want anyway.
Cause 4: Tracked Changes and Revision History
Word retains every tracked insertion, deletion and formatting change, each tagged with author and timestamp. Comments, including resolved ones, persist too.
On a document that has been through five reviewers, this can be a substantial share of the file — and it carries a second risk beyond size. Revision history is a well-documented source of accidental disclosure: earlier drafts, internal comments, and author names all travel with the file.
Fix:
- Review tab → Accept → Accept All Changes.
- Delete all comments (Review → Delete → Delete All Comments in Document).
- Check File > Info > Inspect Document for remaining hidden metadata.
Do this on a copy if you need the revision trail for records.
Cause 5: Embedded Fonts
Under File > Options > Save, if Embed fonts in the file is enabled, Word ships the font data with your document — potentially tens of megabytes for a full family.
If you need embedding for layout fidelity, tick Embed only the characters used in the document, and untick Do not embed common system fonts. There is no reason to send Calibri to a machine that already has it.
Cause 6: The Legacy .doc Format
The old binary .doc format is not compressed. .docx is a ZIP archive of XML, so all the markup is compressed automatically.
Simply doing File > Save As → Word Document (.docx) on an old .doc frequently halves the size, with zero quality loss and no decisions to make. If you have inherited a library of legacy documents, this is the highest-return change available.
When PDF Is the Better Answer
If the recipient needs to read the document rather than edit it, exporting to PDF is often the cleanest way to shrink it.
PDF export discards revision history, editing metadata, un-cropped image regions, and unused resources as a matter of course. And PDF compression tooling is considerably more capable than Word's — you can downsample images, subset fonts, and strip metadata with far more control. See how to reduce PDF size for that side of the workflow.
The tradeoff is obvious: the result is not readily editable. Use it for final documents, not drafts in circulation.
About Online Word Compressors
Plenty of free web tools will compress a DOCX. They generally unpack the archive, re-encode the media, and repack it — the same operations described above, performed on someone else's server.
The functional limitation is that they apply uniform settings and cannot distinguish a photograph from a screenshot.
The larger consideration is what Word documents typically contain. Contracts, HR records, medical letters, legal drafts, client reports. Uploading those to a free service means transmitting them to a third party under a retention policy you have not read. For anything confidential — which is most of what Word is used for — handling the compression locally is the sounder choice.
A Practical Order of Operations
- Duplicate the file.
- Inspect the ZIP to find out what is actually large.
- Save as
.docxif it is still legacy.doc. - Accept all changes and delete comments if the document is final.
- Re-paste embedded charts as pictures.
- Compress images at a resolution matched to the destination, with "Delete cropped areas" ticked.
- Trim font embedding.
- Export to PDF if it only needs to be read.
For most documents, steps 3 and 4 alone do the majority of the work.
Fix the Media, Then the Document
The pattern here is the same one that applies to PowerPoint decks: Office files are containers, and the things making them large are ordinary images that respond to ordinary compression.
Compressing figures properly before they go into a document produces a smaller file and better-looking output than any after-the-fact pass, because you keep per-image control instead of applying one blunt setting to everything.
Compresto compresses the images and video that go into your documents, natively on macOS — batch processing for a folder of figures, format-appropriate handling for screenshots versus photographs, and no uploads, which matters when the document is confidential.