Reduce PDF file size without overlooking the quality trade-off

Identify what is making the document large

A scanned report with high-resolution photographs is a different compression problem from a short PDF containing digital text. First check whether you can select words and whether the file includes pages the recipient does not need. Extracting the necessary pages may solve an attachment limit without converting the remaining pages into images.

Keep the original and note its size before trying compression. Decide what the recipient must do: read the pages on a phone, print fine drawings, search for names or complete a form. Those requirements determine whether an image-only copy is suitable at all.

Try the text-preserving mode first

The default Structural optimization mode repacks the whole document. It does not turn pages into pictures, flatten form fields, resize images or lower JPEG quality. Existing page content and document objects remain in the document. This can compact the PDF structure, but a file already stored efficiently may not get smaller.

If repacking produces an equal or larger file, the download is the unchanged original and the result says that no smaller version was produced. This is a valid outcome, not a promised percentage. The mode handles the entire document, so there is no page-range control. Encrypted PDFs, signature fields and XFA forms are unsupported.

1. Choose your PDF and keep “Keep text and vectors” selected.
2. Create the PDF and read the actual size result.
3. Reopen the download: select a sentence, test a link, check the page order and try any form fields before sharing.

Two-page checked example: page 1 has a name field and city selection; page 2 has text, a vector rectangle and a link. The structural result kept both pages in order, the text selectable, the fields editable and the link present. This example does not guarantee every PDF feature.

When you choose image compression

The separate Image compression mode renders the selected PDF pages and rebuilds them as JPEG images inside a new PDF. This is lossy raster compression. Selectable text, live links, interactive forms, bookmarks and accessibility structure are removed. The page may look similar at first glance while behaving very differently.

A document that started as compact text and vector graphics can become larger after rasterization. There is no guaranteed reduction percentage or exact target-size setting in this PDF tool. If searchable or accessible content is required and structural optimization saves no space, retain the original or adjust the source document in the application that created it.

Test a readable setting before lowering quality further

Resolution controls how many pixels represent the page; JPEG quality controls how those pixels are encoded. They solve different problems. Lower resolution makes tiny letters harder to read, while aggressive JPEG compression can create halos and blocks around text. Raising quality cannot restore detail already lost through a low resolution.

1. Choose Image compression explicitly. Enter a page range only if you want a copy containing that part of the document.
2. Try 96 DPI and 65% JPEG quality as an initial experiment for a scanned reading copy, not a guaranteed recommendation for every document.
3. Create the PDF and compare the actual downloaded size with the original.
4. Inspect small labels, decimal points and signatures at a useful viewing size. Increase DPI or quality if essential details become unclear.

Source: 12-page scanned report
Trial: all 12 pages, 96 DPI, 65% JPEG quality
Accept only if the download is smaller and every required detail remains readable.

Check page coverage and keep the appropriate copy

The tool accepts a source up to 40 MB and 300 pages, but raster processing is limited to 60 selected pages, 72–200 DPI, 12 million pixels per page and an overall pixel budget. Very large page dimensions can require a lower DPI even for a short selection.

In image mode, a selected range produces only those pages, so a smaller output may reflect missing pages rather than compression alone. Structural mode keeps all pages. Compare like with like and check the page count. Download the finished file before closing the tab; the selected document is processed locally in your browser.

If the new PDF is larger, blurred or unsuitable for searching, keep the original. Rename an accepted output as a reading or email copy so that it is not mistaken for an editable master. For a scanned image that needs searchable words, OCR is a separate task and is not performed by this compressor.