Compress PDF to a Specific Size
Upload forms and email systems often reject a PDF by size, not by quality. This tool lets you choose a maximum target such as 100KB, 500KB, or 1MB and tries progressively smaller page images until the result fits. It downsamples the images inside the document to reach the target, and leaves text, vectors, forms and links intact. Until 2026-08-26 it worked by rasterizing every page, which did destroy all of those — that is no longer the case.
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Add to Chrome — freeDownsamples embedded images to reach this target. Text, links and form fields are kept — the older version of this tool rasterized every page and lost them. Works on PDFs up to 25.00 MB.
What it does
- Choose a maximum target in KB
- Tries quality and page-scale candidates
- Reports whether the target was actually reached
- Processes the document locally in the browser
- Warns about rasterization and fidelity loss
How to use Compress PDF to a Target Size
- 1
Enter the maximum size
Choose the maximum output size in kilobytes. Use the limit shown by the upload form or recipient rather than guessing.
- 2
Select the PDF
Drop the source document into the tool. Its page count and current size are shown before anything is compressed.
- 3
Review the result message
The tool tries several quality and scale combinations. It reports the actual size and tells you when the target was impossible with the available candidates.
- 4
Inspect before submitting
Open the output and check small text, signatures, forms, links, images, page count, and readability before replacing the original.
How it works
The browser first opens the PDF and renders each page to a white canvas. It then tries a sequence of JPEG qualities and page scales, rebuilds a PDF for each candidate, and stops at the first result that is no larger than the requested target. The tool reports the actual output size, quality, page scale, and whether the target was reached. There is no promise that every source can fit every limit.
This is fundamentally different from a lossless PDF rewrite. The structural PDF Compressor preserves the document model and may remove overhead, but it cannot shrink a large photograph inside a PDF without re-encoding it. Target-size compression makes that trade visible: it can be useful for a portal limit, but it is not a safe replacement for the original document.
Choose the right mode
Use this page when a receiving form says “maximum 1MB” and the document is a disposable derivative. Try a larger target first, because a little extra room can preserve much more legibility. Use the ordinary compressor for reports, contracts, accessible PDFs, forms, and files with digital signatures. Use OCR when the source is a scan and searchable text is more valuable than a tiny raster copy.
Check the output
Target-size checklist
Start with the largest limit the recipient allows instead of forcing the smallest possible file immediately. Inspect fine type, tables, barcodes, signatures, gradients, and page edges at normal reading size. If the PDF contains a form or a scan, compare a few pages at high zoom and confirm that text remains distinguishable. Keep the original beside the derived copy until the upload or email has been accepted. A smaller file is not automatically a better file: a target that destroys a total, label, or signature has failed the actual handoff even if it passes the byte limit.
Open every page at normal reading size. Inspect fine print, tables, seals, signatures, barcodes, dark gradients, and page edges. A PDF that passes a byte limit but makes a number unreadable has not solved the real problem. Keep the original file until the recipient has accepted the derived copy, and never use a target-size raster copy as the authoritative archival record.
Examples
A government upload limit
The result fits the form limit, but the applicant should inspect small text and preserve the original source.
A scan with a very small target
A photographic scan may need a larger limit because pushing it farther would make text unreadable.
Frequently asked questions
Does this preserve selectable PDF text?
Not reliably. This target-size mode renders pages into JPEG images before rebuilding the PDF, so selectable text, vectors, forms, links, tags, and accessibility structure may be lost. Keep the original and use structural compression when fidelity matters.
Why was my target not reached?
Some documents contain large scans or detailed images that cannot fit the requested size without severe quality loss. The tool reports the smallest candidate it could create instead of claiming success for a larger file.
Is the PDF uploaded?
No — and how it works changed on 2026-08-26. The file is sent to Prathom's own server, processed there, and deleted the moment the response is sent; nothing is stored and no account is needed. It used to run inside the browser tab, which was slower, capped by the memory that tab had, and — for several of these tools — produced worse output. The output is also far better than it was: this tool used to rasterize every page to hit a size, destroying selectable text, links and form fields. It now downsamples only the embedded images.
Should I use this for a signed PDF?
No. Rebuilding a PDF changes its bytes and can invalidate digital signatures, forms, annotations, links, and document structure. Use this only for a derived upload copy after confirming the destination accepts a raster PDF, never as the signed original.
Further reading
- Converting a PDF to Grayscale Made It BiggerRemoving color sounds like removing data, so grayscale gets used as a compression step. On a document that was already black text on white, the conversion made the file larger — and the reason it did is the reason it sometimes makes a scan dramatically smaller.
- Zipping 500 Tiny Files Made the Archive Bigger Than the FilesA zip is supposed to make things smaller, and on a folder of many small files it can do the opposite. Each entry carries its own header, its own directory record and its own compression stream, and below a certain file size that bookkeeping is bigger than the file.
- What "Compress PDF" Actually Removes, Preset by PresetNearly every "compress PDF" tool is Ghostscript underneath, running one of five named presets. Those presets do very different things, the differences are not what their names suggest, and the one that produced the smallest file also produced the worst-looking page. Here is all five measured on the same document.