pdf-compress-tool

Compress PDF files to a target size or by percentage, using a Ghostscript + pikepdf + QPDF multi-stage pipeline.

Performs actual PDF compression, supporting both target size and percentage modes. Unlike existing solutions that only provide guidance, this tool compresses files directly.

Features

• Two compression modes: target size (--target-size 2MB) / percentage (--reduce 30)
• Three-stage compression pipeline: pikepdf structural optimization → Ghostscript progressive compression → QPDF secondary optimization
• Quality floor protection: three levels (high / medium / low) to prevent excessive compression from damaging image quality
• Batch processing: compress all PDFs in a directory at once
• Auto dependency detection: detects available tools at runtime and adapts compression strategy accordingly

Usage

Compress to target size

"Compress this PDF to under 2MB"
"Compress this PDF to under 5MB"

python compress_pdf.py report.pdf --target-size 2MB

Compress by percentage

"Reduce the file size by 30%"
"Reduce the file size by 50%"

python compress_pdf.py report.pdf --reduce 30

Specify output path and quality

python compress_pdf.py report.pdf --reduce 50 --quality low -o small.pdf

Batch processing

"Compress all PDFs in the papers folder to under 2MB"

python compress_pdf.py --batch ./papers --target-size 2MB
python compress_pdf.py --batch ./papers --reduce 40 --quality high

Compression Strategy

Stage 1: pikepdf structural optimization

Removes redundant objects, compresses streams, and packs object streams. Lossless operation that preserves maximum image quality.

Stage 2: Ghostscript progressive compression

Tries prepress → printer → ebook → screen progressively, checking at each level and stopping as soon as the target is met. Also supports custom DPI downsampling (100 → 72 → 50 → 36 dpi), subject to quality floor protection.

Stage 3: QPDF secondary optimization

Object stream generation and stream recompression, saving an additional 5-15%. Requires qpdf installation (optional).

Quality floor protection

Level	Meaning	Minimum compression level	Use case
high	Quality priority	printer (300dpi)	Documents intended for printing
medium	Balanced (default)	ebook (150dpi)	Everyday use
low	Size priority	screen (72dpi) and below	Screen viewing only

Dependencies

• python3 (required)
• ghostscript (recommended): core compression engine
• qpdf (optional): secondary structural optimization, additional 5-15% compression
• pikepdf (auto-installed via pip): Python PDF library, fallback when Ghostscript is unavailable

Install by platform

Dependency	macOS	Linux (Debian/Ubuntu)	Linux (RHEL/Fedora)	Windows
ghostscript	brew install ghostscript	sudo apt-get install ghostscript	sudo dnf install ghostscript	choco install ghostscript or download
qpdf	brew install qpdf	sudo apt-get install qpdf	sudo dnf install qpdf	choco install qpdf or download
pikepdf	pip install pikepdf (auto)	pip install pikepdf (auto)	pip install pikepdf (auto)	pip install pikepdf (auto)

The script auto-detects your platform and shows the correct install command when a dependency is missing.