PDF guides
PDF Compression Levels Explained: Low vs Balanced vs High
Compress PDF offers three levels — Low, Balanced, and High — and they are not just three points on the same slider. Low is a structural, lossless rebuild; Balanced and High rasterize every page into an image. This guide compares what you gain and give up at each level so you can pick the right one before you download.
Ready to try the tool this guide describes?
Low compression / higher quality
Low compression loads the PDF with pdf-lib, copies every page into a brand-new document, and saves it with compact cross-reference streams. Nothing is rasterized: text stays selectable, vector graphics stay sharp at any zoom, and page dimensions are untouched.
The tradeoff is that the size reduction depends entirely on how much structural overhead the original file had. A PDF exported from a word processor often shrinks noticeably; a PDF that was already produced by a lossless rebuild — including one already compressed by this tool — may shrink very little or not at all.
Balanced and High compression
Balanced renders each page to a canvas at roughly 1.5x scale and saves it as a JPEG at around 75% quality; High renders at roughly 1x scale and around 50% quality. Both rebuild the PDF as one full-page image per page, which reliably shrinks image-heavy or scan-like PDFs where Low compression would not help.
The cost is the same for both: text is no longer selectable or searchable, and anything interactive in the original PDF — form fields, links, bookmarks, structure tags — does not survive being flattened into an image. High compression pushes this further with a smaller image and lower quality, so fine text or small print may look noticeably softer than at Balanced.
| Level | How it shrinks the file | Text selectable? | Typical use |
|---|---|---|---|
| Low | Lossless structural rebuild | Yes | Text-heavy PDFs you still need to search or copy from |
| Balanced | Rasterize pages, higher quality JPEG | No | General-purpose size reduction |
| High | Rasterize pages, lower quality JPEG | No | Maximum size reduction, quality is secondary |
Choosing a level for your document
- Need to keep copying/searching text later? Use Low.
- Sharing a scan or image-heavy PDF and want a real size drop? Use Balanced.
- Hitting a strict upload size limit and quality is secondary? Use High.
- Not sure? Try Balanced first — Looty Tools will tell you plainly if the result was not meaningfully smaller.
Compression Levels Explained FAQ
- Can I try more than one level on the same file?
- Yes. The file stays loaded after a compression run — pick a different level and select Compress & download again without re-uploading.
- Does a higher level always produce a smaller file?
- Usually, since Balanced and High rasterize at a lower scale and quality than Low’s lossless rebuild. But results depend on the source PDF — Looty Tools always reports the actual size difference rather than assuming one.
- Do Balanced and High change the page dimensions?
- No. Each output page is sized to match how the original page displays, including its existing rotation, so orientation and proportions are preserved even though the content becomes an image.
- Are my files uploaded?
- No. All three compression levels run locally in your browser.
- What happens if a page is too large to rasterize?
- Balanced and High compression include a maximum canvas size guard. If a page would exceed it, compression stops with a clear error instead of risking a crash — try Low compression or a smaller file.
Related guides
- How to Compress a PDFShrink a PDF in your browser: choose Low, Balanced, or High compression, and understand exactly what each level trades off before you download.
- Why Won't My PDF Shrink?Understand why some PDFs barely shrink with compression, how to tell a genuine size reduction from a false one, and what to try next.
- How to Convert PDF to JPGRasterize PDF pages to JPG or PNG with quality and resolution controls, ZIP downloads, and the current page and size limits.