PDF Compressor

The PDF Compressor reduces the file size of a PDF document. Upload your PDF, click Compress PDF, and download a smaller version of the same document — with the same layout, text, and page content, but with embedded images re-encoded at a more efficient quality and redundant internal data removed. The result is a PDF that emails faster, uploads to portals without hitting size limits, and takes up less storage space.

How much compression is achievable depends almost entirely on the content of the PDF. A color-scanned document or image-heavy brochure can shrink by 50–80%. A text-only contract or email-exported invoice may shrink by only 5–15% because there is no image data to compress. Understanding what is inside your PDF is the best predictor of how much it will reduce.

How to use the PDF Compressor

1. Click Select a File or drag and drop your PDF. Guest users can upload up to 5 files (10 MB each); registered users up to 20 files (40 MB each).
2. Click Compress PDF. The tool analyses the document, re-encodes embedded images at optimized quality, removes redundant data, and produces a compressed PDF.
3. Download the compressed PDF. Compare its file size to the original to confirm the reduction, and open it to verify that images and text remain clear and readable before sharing.

What PDF compression does — and does not do

PDF compression primarily works by re-encoding embedded images. Images inside a PDF — photographs, scanned page backgrounds, embedded graphics — are often stored at a higher resolution or quality than necessary for screen viewing or standard printing. The compressor re-encodes these images using more efficient settings: lower quality JPEG encoding for photographs, down sampling high-DPI images to 150 DPI (sufficient for screen use), and removing embedded thumbnail previews and duplicated image data.

Text content in a PDF — actual characters, fonts, vector shapes — is not meaningfully compressed by re-encoding images. Text compresses very efficiently to begin with, and its contribution to file size is already small. This is why a PDF that is 95% black text and 5% color elements compresses by only a small percentage, while a PDF that is 80% embedded photos compresses dramatically.

Compression does not degrade text quality. Text in a PDF is stored as vector data — mathematical descriptions of character shapes — not as pixels. Re-encoding images does not affect text. Every character in the compressed PDF is rendered at full sharpness regardless of compression level. The only content that changes quality is embedded raster images — photographs, scanned page backgrounds, and embedded bitmaps. Vector graphics (shapes, lines, diagrams drawn in design software) are also unaffected.

Realistic compression expectations by PDF type

The table below sets practical expectations based on what the PDF contains — the single biggest factor in how much reduction is achievable:

If the PDF is already close to your target size but still slightly over a limit, combine compression with two other approaches: (1) use Remove PDF Pages to delete any pages not needed by the recipient — blank pages, redundant appendices, cover pages for internal circulation; (2) use the Grayscale PDF converter before compressing — converting color images to greyscale before running the compressor can produce 30–60% additional reduction on color-heavy PDFs. The workflow section below covers this combined approach step by step.

Common file size limits — what you are trying to get under

Most users compress PDFs to get under a specific limit. The table below covers the most common contexts:

Getting the smallest possible file — a four-step workflow

When standard compression alone does not get the PDF under your target size, the following four-step workflow produces the maximum achievable reduction. Each step is independent — apply only the steps appropriate for your document:

When compression will not help significantly

Setting accurate expectations saves time. PDF compression produces minimal results in these scenarios:

• The PDF is already optimized. PDFs exported by tools that apply compression by default (Adobe Acrobat, many web-based generators, Microsoft 365 save-as-PDF) may already be at or near minimum size. Running them through a second compressor achieves little additional reduction.
• The PDF is text-only. Contracts, invoices, letters, and reports containing only black text and simple vector elements have very little image data to compress. File size savings of 5–15% are typical.
• The PDF contains high-quality images that must remain sharp. If the document requires photographic images to be readable at full quality — medical images, architectural drawings, product photography for print — aggressive compression degrades those images unacceptably. In this case, reduce size by other means: remove pages, reduce page count, or split the document.
• The file size is driven by embedded fonts. PDFs that embed complete font sets rather than subset-embedding only the used characters can have significant file size from font data. Standard image compression does not reduce this. Font sub setting requires dedicated PDF optimization tools.

Usage limits

Related tools

• Remove PDF Pages — delete unnecessary pages before compressing to reduce file size at source.
• Grayscale PDF — convert color images to greyscale before compressing for maximum size reduction on color-heavy PDFs.
• Merge PDF — combine multiple compressed PDFs into one document.
• Watermark PDF — add a CONFIDENTIAL or DRAFT watermark after compressing before distributing.

Frequently asked questions

Will compression reduce the quality of my PDF?

Text quality is not affected at all — text in a PDF is stored as vector data and is not touched by image compression. The quality of embedded photographs and scanned images may reduce slightly depending on the compression level applied. For most documents, the quality reduction in images is not noticeable at normal viewing size. If the PDF is opened and zoomed in closely on photographs, some reduction in image sharpness may be visible. If image quality is critical — medical images, print-quality photography, detailed technical diagrams — review the compressed output carefully before distributing.

Why is my PDF still large after compressing?

Three common causes: (1) the PDF is already optimized — it was created by a tool that applies compression by default, and there is little remaining redundancy to remove; (2) the file size is driven by text, fonts, and vector content rather than images — text-only PDFs compress minimally; (3) the PDF contains images that are already at a low resolution or already JPEG-compressed — re-compressing already-compressed images achieves little additional reduction and may degrade quality. In these cases, the most effective ways to reduce size further are to remove unnecessary pages, convert color images to greyscale before re-compressing, or split the document into smaller sections.

How much will my PDF compress?

Color-scanned documents and image-heavy PDFs typically compress by 50–80%. Mixed content documents with reports, charts, and some photography compress by 20–50%. Text-heavy PDFs with minimal images compress by 5–20%. PDFs that are already optimized compress by 0–10%. The compression expectations table above gives detailed guidance by PDF type. The best predictor is the ratio of embedded image data to text and vector content — the higher the proportion of images, the more the PDF will compress.

Does compression change the layout or formatting?

No. Compression does not alter page dimensions, margins, font sizes, text flow, table structure, or any other aspect of document layout. The only change is to the quality of embedded raster images — photographs and scanned backgrounds are re-encoded more efficiently. Every page in the compressed PDF looks identical to the original at normal viewing size. Layout and formatting are preserved exactly.

My PDF needs to be under 5 MB for a portal upload but compression alone is not enough. What should I do?

Use the three-tool workflow: (1) Remove PDF Pages — delete any pages not needed for this submission; blank pages, cover letters, and appendices add file size without content value. (2) Grayscale PDF — if color is not required, converting to greyscale before compressing provides the largest additional size reduction for color-heavy documents. (3) Compress — run the compressor on the reduced, greyscale PDF. If the document is still too large after all three steps, it may need to be split into separate submissions, or high-resolution images in the source document may need to be reduced before generating the PDF.

Can I compress multiple PDFs at once?

Yes. Guest users can upload up to 5 PDF files per session; registered users up to 20. Each file is compressed individually and is available to download. For batch compression of many files, registering a free ToolsPiNG account gives higher session limits.

Does the compressor work on scanned PDFs?

Yes — scanned PDFs are often the best candidates for compression. A scanned PDF is essentially a collection of photographs of pages, so it is almost entirely composed of image data. Color scans of printed documents typically compress by 50–80%. Black-and-white scans compress by 20–40%. The quality of the scan affects the result: a clean, high-contrast scan compresses more cleanly than a blurry, noisy, or skewed scan. For scanned PDFs intended for long-term archiving, verify that the compressed output remains clearly legible before replacing the original.

Is the PDF Compressor free?

Yes. The compressor is free within the daily usage limits shown above. Guest users can run 25 compression sessions per day and upload up to 5 files per session (10 MB each) without creating an account. Registering a free ToolsPiNG account increases the daily limit to 100 sessions, the file size limit to 40 MB per file, and the per-session file count to 20.