Compress a PDF to fit a target size
Try to reduce a PDF to fit a 100 KB, 200 KB, 500 KB, 1 MB, 2 MB or 5 MB limit, directly in your browser. The tool stops at the first tested setting that fits and reports if the target cannot be reached.
- Add your PDF and choose the required size limit.
- Select Compress to target size.
- Read the result message, then check the downloaded file size and readability.
Try public sample PDFs · Verify local processing and browser requirements
How it works
A JPEG's final byte count cannot be predicted from its settings — it depends on how much detail the source image contains, because the discrete cosine transform at the heart of JPEG spends bytes only where there is visual complexity to describe. A quality setting that lands a clean invoice at 40 KB per page can leave a photographed whiteboard at 300 KB per page. So the only honest way to hit a hard size limit is to try, measure, and try again.
That is exactly what this tool does. It walks a fixed ladder of seven rungs, each a resolution and JPEG-quality pair: 144 dpi at quality 0.8 on the top rung, stepping down through intermediate combinations to 43 dpi at quality 0.25 on the bottom. At each rung, every page is rendered by the pdf.js engine onto a canvas at that rung's resolution, encoded as a JPEG at that rung's quality, and assembled into a candidate PDF. The candidate's actual byte size is measured against your target — anything from 100 KB to 5 MB. The first rung that produces a file under the limit wins, which by construction gives you the first quality setting in the tested sequence that fits.
Two edge cases are handled explicitly. If your file is already under the target, it is passed through byte-for-byte untouched — recompressing it would cost quality and gain nothing. And if even the bottom rung's 43 dpi output is still over the limit — a 200-page scan aimed at 100 KB, say — you receive that smallest achievable file along with an honest report of the shortfall instead of a silent failure. In that situation, splitting the PDF into parts under a size limit usually serves the real goal better than crushing every page into illegibility.
One property is inherited from rasterization itself and worth knowing before you start: like the standard compressor, this tool rebuilds each page as a flat image. Text stops being selectable and searchable in the output, and links and form fields disappear. The original stays untouched on your disk, so keep it as the authoritative copy.
Illustrative example: a 4.6 MB application form to under 200 KB
Illustrative scenario, not a recorded benchmark. File sizes, timings and results depend on the input and device. Try the reproducible samples.
A government job portal demands each attachment stay under 200 KB. The applicant's signed, phone-scanned form is 3 pages and 4.6 MB — roughly 1.5 MB per page of full-resolution camera JPEG.
With the target set to 200 KB, the tool starts at rung one: 144 dpi, quality 0.8. That candidate comes out at 412 KB — better, but over. Rung two lands at 296 KB, still over. Rung three, at reduced resolution and quality 0.5, produces 187 KB — under the limit, so the ladder stops and that file is delivered. The result is a 96% reduction in which the printed form text is still clearly legible on screen, though fine print is visibly softer than in the original. Had the applicant instead requested 100 KB, the ladder would have continued downward and delivered a 94 KB file at rung five, readable but noticeably fuzzy — the honest cost of a very tight limit on a 3-page scan.
Compress to a target size — frequently asked questions
How do I compress a PDF to fit under 100 KB?
Set the target to 100 KB and drop your file in; the tool re-encodes the pages at progressively lower resolution and JPEG quality until the output fits under 100 KB. You get the first rung of the ladder that succeeds, so the first successful setting in the tested sequence is used.
What happens if my PDF cannot be compressed down to the target size?
If even the lowest setting, 43 dpi at quality 0.25, is still over the limit, you get that smallest achievable file plus a report saying the target was missed and by how much. Long documents sometimes simply contain too many pages for a tiny limit; splitting the file is the practical fix.
Will the text still be selectable after compressing to a target size?
No. Like any rasterizing compressor, this tool turns each page into a JPEG image, so text objects, fonts, links, and form fields are gone in the output. Keep the original file if you may need to copy or search the text later.
What if my PDF is already smaller than the target size?
It is passed through untouched. Recompressing a file that already fits would only degrade it for no benefit, so the tool detects this case and returns your original bytes unchanged.
Is the PDF uploaded to a server to be compressed to size?
No. Rendering, JPEG encoding, and the size checks all run in JavaScript inside your browser, so the file never leaves your device. That also means there is no upload size cap; memory is the only limit.
What target sizes can I choose?
Anything from 100 KB up to 5 MB, covering the common limits of job portals, government forms, and email attachments. If you need parts under a limit rather than one small file, splitting by size preserves quality better.