How to Flatten a PDF Online (What You Lose, and the File Size)
Flatten a PDF by turning every page into one image — the text stops being selectable, searchable or editable, and the file usually gets bigger. Picks the right DPI first.
Flattening means rasterizing, not hiding
Flattening a PDF means rendering every page to a picture and building a new file in which that picture is the whole page. Nothing is hidden behind an overlay and nothing is left selectable: the text is drawn into the image, so it can no longer be selected, searched, copied, edited or re-flowed in any reader. That is the honest promise of flattening — a fixed record of what the page looked like when you flattened it.
The same thing happens to everything else that lives on the page. Links, form fields and their filled-in values, comments, highlights, stamps, annotations, optional-content layers and hidden text all become part of the picture. The rebuilt file is also a new document, so the source's bookmarks and its metadata — author, title, producer, creation date — are not carried over. If you need any of that afterwards, keep the original: flattening cannot be undone from the output.
Why the file gets bigger, and which DPI to pick
Vector text is extremely compact; a rendered picture is not. A page that weighed a few kilobytes of text can become several hundred kilobytes of image, so a flattened copy of a long document is regularly several times the size of the original. That cost buys the loss of the text layer, so it is only worth paying when you specifically need a picture-only file.
Three raster settings are offered, and each one is a real trade-off. Screen renders at 96 DPI as JPEG for the smallest file, fine for reading on a screen but soft on small print. Balanced, the default, renders at 150 DPI as JPEG and suits everyday viewing and email. Print renders at 200 DPI as lossless PNG — the sharpest and by far the largest. Screen and Balanced are lossy JPEG, so very small type can show compression artifacts when you zoom in; only Print is lossless. An unusually large page is rendered below the chosen DPI to stay inside the browser's canvas limit, and the tool reports how many pages were affected instead of failing.
Flattening the document
Open the PDF in the tool and it reports the page count. Files up to 100 MB and 200 pages are supported; a password-protected file cannot be opened here, so remove the password with the PDF Unlock tool first and flatten the unlocked copy. Choose a raster setting, then click Flatten: each page is rendered on your device and the new PDF is assembled with one image per page, so you can watch it work page by page.
Everything happens in your browser. The PDF is never uploaded, and your original file is not modified — every run produces a separate download named <source>-flattened.pdf. A rotated page is flattened in the orientation you see it, and every page keeps its own dimensions, so the output reads the same as the input even though the underlying content is gone.
Download, then check before you send it
After the run you get the output size and how it compares with the original — check that first, because a much larger file is the normal outcome rather than a fault. Open the flattened copy in a desktop reader and confirm the text can no longer be selected or searched, and that the pages still look right at the zoom level you need. This tool does not add an OCR text layer back, so if you need searchable text as well, keep the original and run PDF OCR on it instead.
Share only the flattened copy, and keep the original file if you might still need to read, copy or edit the text. Flattening is irreversible from the output, and the absence of a text layer also means screen readers and copy-paste workflows no longer work on that file — a real accessibility cost worth weighing before you lock a document down.
Try it free — Flatten PDF
Rasterize a PDF so each page becomes a single image — text is no longer selectable or editable, everything is locked into the page.
Open Flatten PDF