Get a PDF under an online form's size limit

Under Fit under a size, type a number in KB or tap one of the quick sizes. When you click Fit under, the tool works down a ladder of settings and stops at the first one whose result is under the limit. If the file is already under the limit, it is handed back unchanged and the note says so. The Compress PDF to 100KB and Compress PDF to 200KB pages open the same tool with that size already in the box.

The first four rungs only touch the images. Light, Balanced and Strong are the same settings as the levels of the same name, and Very strong goes further, capping images at 800 pixels on the longest edge at a low JPEG quality. Text, links and form fields are left alone on these rungs, so the result still reads and searches like the original. If they are not enough and Flatten pages to images if that is the only way to fit is ticked, as it is by default, the tool renders each page as a picture, first at 110 dpi, then 90, 72, 60 and finally 50 dpi.

It does not try every rung blindly. If the image rungs cannot shrink the file at all, it goes straight to flattening. After one flattened attempt it estimates which resolution could fit and jumps there, and if even 50 dpi would not get under the limit, it stops and gives you the smallest result it reached.

The note under Your file is ready names the setting that worked, for example 2.4 MB down to 180 KB, under the 200 KB target, using Strong. Light keeps images up to 2,400 pixels on the longest edge at a high JPEG quality, Balanced 1,600 pixels, Strong 1,100 pixels at a lower quality, and Very strong 800 pixels at a lower quality still. On a scan, check that small print such as a reference number is still readable.

A setting called Flatten at 110 dpi, or a lower number, means the pages were rendered as pictures, and the note adds that the text is no longer selectable. It cannot be searched, copied or read by a screen reader, and fillable form fields are gone, because the new file holds pictures of the pages and nothing else. At 72 dpi and below small print starts to blur, so open the file and read it before you upload it.

To keep the text, untick Flatten pages to images if that is the only way to fit before you click. The tool then stops at the smallest size the image settings can reach, and if that is still over the limit, the note says so and suggests allowing flattening or splitting the document.

If no setting gets under the limit, you get the smallest version the tool reached, saved with a -compressed suffix instead of -under-200KB, and a note that begins Could not get under 200 KB. A text-only PDF often ends here: it has no images to re-encode, and a page of text rendered as a picture usually comes out larger, not smaller. Some images are also skipped by the image rungs 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.

When the target is met, the file is saved under the original name with -under-200KB added, or whatever size you set, so it sits beside your original. Compare the size in the note with the form's limit, then open the file and check the pages that matter, such as a signature or a stamp. The tool counts a kilobyte as 1,024 bytes; some portals count 1,000, so if a file reported just under the limit is still refused, set the box about 5 percent lower.

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 add several files, each is fitted under the limit on its own and the note describes each in turn; Download all as ZIP stores them without further compression, so each must still meet the limit alone.