How to Compress a PDF to a Target Size (100 KB, 1 MB, or Under a Limit)

Updated Jul 23, 2026 2 min read No upload — runs in your browser

To compress a PDF to a target size, open the Compress PDF tool, drop your file, type the size you need into the “Target size in KB” box (e.g. 100), and download the result. The tool finds the highest quality that still fits under your limit — automatically, on your own device, with nothing uploaded.

Government portals, job-application forms and court e-filing systems love a hard cap: “PDF must be under 2 MB,” “max 100 KB,” “no larger than 500 KB.” A plain quality slider turns that into trial and error — export, check the size, adjust, repeat.

You don’t have to guess.

Hit an exact size in your browser

  1. Open Compress PDF.
  2. Drop the PDF on the page.
  3. In Target size in KB, enter your limit — 100 for 100 KB, 1000 for ~1 MB, 2000 for ~2 MB.
  4. Download the file. It comes out at or below your target.

When you set a target, the quality slider steps aside — the tool searches for the best quality that still fits, so you get the sharpest file allowed under the cap.

How the target search works

Behind the box is a simple, reliable idea: quality and size move together, so the tool does a binary search across quality levels. It encodes at a middle quality, checks the size, and narrows in — a handful of attempts land on the highest quality that stays under your number. No manual fiddling, and it runs entirely in the tab.

What to expect at aggressive targets

Compression here works by rasterising pages — rendering each to an image and re-encoding it. That has consequences worth knowing when you push the target low:

  • Very small targets soften scanned text. Asking a 20-page scan to fit 100 KB will blur it. If the form allows more, give it more.
  • Text stops being selectable. The page becomes a picture of a page — expected for scans, usually the wrong trade for a clean text PDF.
  • Some files can’t reach tiny targets without becoming unreadable. If yours won’t, the honest fixes are below.

If it won’t fit the limit

  • Split it. If the form only needs certain pages, Split PDF pulls out a range — far more effective than crushing quality.
  • Remove heavy images from the source document if they’re decorative.
  • Lower the scan resolution. Scanning at 600 dpi when 200 dpi would do makes the file roughly nine times larger before you begin.

Frequently asked questions

How does hitting an exact PDF size work?

You give a KB target and the tool adjusts image compression to land under it, so you don't guess at a quality slider to satisfy an upload form's limit.

Can every PDF reach any target?

No — a text-and-vector PDF has little to compress, so it may already sit near your target with nowhere to go. Image-heavy PDFs have the most room to shrink.

Is the file uploaded to measure its size?

No. The compress-and-check loop runs entirely in your browser; nothing about the document leaves your device.

What if I need it under a very small limit?

If compression alone can't get there, removing pages you don't need or splitting the PDF is the reliable way under a tight cap.

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