Compressing PDF Files with Ghostscript

I shrank a 724 MB PDF to 29 MB with the open-source tool Ghostscript. Here are the command and options I used.

What is Ghostscript?

Ghostscript is an open-source interpreter for PostScript and PDF. It's used for PDF compression, conversion, and rendering. It's free and supports Windows, Mac, and Linux.

Installation

Download the installer from the official site and run it. (This post covers Windows.)

After installation, the executable will be at:

TEXT

C:\Program Files\gs\gs10.06.0\bin\gswin64c.exe

The Command

Bash

MSYS_NO_PATHCONV=1 "C:/Program Files/gs/gs10.06.0/bin/gswin64c.exe" \
  -sDEVICE=pdfwrite \
  -dCompatibilityLevel=1.4 \
  -dPDFSETTINGS=/ebook \
  -dNOPAUSE -dQUIET -dBATCH \
  -sOutputFile="output.pdf" "input.pdf"

Note for Git Bash on Windows: Arguments starting with /, like /ebook, get converted into Windows absolute paths, which breaks the command. Prepend MSYS_NO_PATHCONV=1 to prevent this.

Quality Settings

-dPDFSETTINGS sets the image resolution, which changes file size and quality:

Option	Resolution	Best For
`/screen`	72 dpi	Screen viewing, smallest file size
`/ebook`	150 dpi	General documents, balanced quality
`/printer`	300 dpi	Print-ready documents
`/prepress`	300 dpi	Publishing, preserves color information

I used /ebook, and the quality was good enough for me.

Results

File	Size
Original	724 MB
Compressed	29 MB
Reduction	96%

Wrapping Up

Ghostscript was easy to install, and one command shrank the PDF a lot. If quality matters, use /printer. If size is the priority, use /screen.