How to Reduce PDF File Size

The fastest way to shrink a PDF is to use an online compressor. Modern tools run entirely in your browser, so your file never leaves your device — a major privacy win over older server-based services. You drop the PDF in, pick a quality level, and download the smaller version in seconds.

This method works well for PDFs that contain scanned images or photographs, which is where most file size comes from. Text-heavy PDFs see only modest reduction because there is little to compress.

The Compress PDF tool on this site uses this approach. It runs locally, has three quality presets, and shows you the before-and-after sizes so you can decide whether the trade-off is worth it.

If you created the PDF from Word, PowerPoint, InDesign, or any other authoring tool, re-export with the 'Minimum size' or 'Web optimization' option selected. Most export dialogs include this option, and it applies compression at the source — which often produces better results than compressing an already-exported PDF.

In Microsoft Word, choose File → Save As → PDF, then click the Options button and check 'Minimum size (publishing online)'. In Google Docs, choose File → Download → PDF Document; Google's default export is already well-optimized.

Re-exporting is also useful when your PDF has unnecessary content — comments, hidden layers, embedded fonts that aren't actually used — that bloats the file but isn't visible. Starting fresh from the source application often strips this out automatically.

If your PDF includes photographs or scanned pages, the source images are usually the largest contributor to file size. Resize and compress these images before inserting them into the source document and you will see dramatic reductions in the final PDF.

Aim for 150 DPI for screen viewing and 300 DPI for print. A 4000 × 3000 photo from a modern phone is overkill for a PDF that will be read on a laptop screen — resize it to 1920 × 1440 or smaller first. Save as JPG at 80% quality for photos, or PNG for screenshots with text.

Free image editors like GIMP, Photopea (browser-based), and the built-in Preview app on macOS all support batch resizing and compression. Spend two minutes on this step and your final PDF can shrink by 80% or more.

PDFs can embed the full font files used in the document, which ensures the document looks identical on every device but adds significant file size. A single font can add 100–500 KB, and a document using five fonts can easily gain 1–2 MB just from font data.

Most PDF creation tools support font subsetting, which embeds only the specific character glyphs used in the document. If your document uses the word 'Hello' in a particular font, only the letters H, e, l, and o are embedded — typically a few kilobytes instead of hundreds.

In Adobe Acrobat, look for 'Save as Other → Reduced Size PDF' and ensure 'Embed only the fonts used' is selected. In LibreOffice, the PDF export dialog has a similar option under the General tab.

If a single PDF is genuinely large because it contains a lot of content (a 200-page report, a multi-chapter thesis), compression can only do so much. In these cases, splitting the PDF into logical chunks — one per chapter or section — is often the most practical approach.

Use the Split PDF tool to extract page ranges into separate files. A 50 MB report split into five 10 MB chapters is much easier to email, upload, and review than a single 50 MB file.

Splitting also helps with accessibility: readers can download only the chapter they need, instead of pulling down a massive file just to read the first few pages.