Get a PDF under an online form's size limit

The tool works on images, not toward a size goal. At Light, Balanced and Strong it walks through the JPEG images in the document, scales any whose longest edge is above that level's ceiling, re-encodes them at that level's quality, then rewrites the file with object streams so unused objects and duplicated structure are dropped. Text and vector graphics are never touched, so they stay sharp and selectable, and a PDF that is mostly text has little to give up.

The result therefore depends on what is inside the document. A page scanned as a photograph has plenty to re-encode; a text-only export has almost nothing. So you get four fixed levels rather than a target, plus a report of the size reached.

Start with Balanced, selected by default and described as the usual choice for email. It caps embedded images at 1,600 pixels on the longest edge and re-encodes them at a middling JPEG quality. Light keeps images up to 2,400 pixels at a higher quality, described as barely visible quality loss, and saves the least.

If Balanced leaves you above the limit, click Start over, add the file again, and choose Strong, described as the smallest file that still keeps text. It drops the ceiling to 1,100 pixels and lowers the JPEG quality further. Photos and scans look softer, while text and layout are unchanged. On a scan, check that small print such as a reference number is still readable.

Flatten to images is the fourth level. It renders every page to a JPEG at 120 dpi and builds a new document from those pictures, often a large saving on a scan stored at a higher resolution. A warning appears when you select it: the text can no longer be selected, searched, or read by a screen reader. Fillable form fields are not carried over either, because the new file holds pictures of the pages and nothing else. Flatten never hands back your original, so a text-only PDF can come out larger than it went in. Use it on scans, not on a form somebody has to read text from.

If the rewrite at Light, Balanced or Strong is not smaller than the original, the tool hands the original back unchanged under its own name, and the note says no saving was possible and that the file is probably already optimized or has no images to re-encode. Several things are skipped on purpose. Only images stored as a plain JPEG are re-encoded, so a Flate-compressed scan is left alone. CMYK and indexed-color images are skipped because the browser canvas gives back RGB and would shift their colors, as are the transparency masks attached to other images. Images whose stored data is under 16 KB are left alone, and a re-encoded image is discarded unless it is at least 5 percent smaller than the one it replaces.

When that happens, change what you send rather than how it is compressed. Organize PDF shows the pages as thumbnails with a delete button on each, so you can drop pages the form does not ask for. Split PDF offers Custom ranges, one output file per line, and Extract pages, which pulls chosen pages into one file.

The compressed file is saved with a -compressed suffix, so it sits beside your original. The note under Your file is ready gives the size before and after and the percentage saved, and the after figure is the one to compare with the form's limit. Open the file and check the pages that matter, such as a signature or a stamp.

Read the form's own rules while you are there. Some ask for a page count, dimensions or a file type as well as a maximum size, and compression cannot fix those. If you compressed several files, the note sums them, so check each size in the list below it; Download all as ZIP stores the files without further compression, so each must still meet the limit alone.

Everything happens in your browser; the line under the button reads processed in your browser, this file is never uploaded anywhere. Files up to 100 MB are accepted, twenty at a time, and above 50 MB a warning says large files are processed in memory and may struggle on a phone.