PDF troubleshooting
Why is my PDF so large?
Large PDFs are usually large because of what they contain, not because PDF itself has a fixed size overhead. High-resolution images and scans are common causes, but embedded fonts, attachments, forms, layers and other objects can also add weight.
Updated August 10, 2026
Quick answer
Images and scans are often the biggest contributors.
A photograph-heavy or scanned PDF can contain millions of pixels per page. Reducing image resolution or applying appropriate compression can make a major difference, but aggressive optimization can permanently reduce quality. Always keep the original when quality matters.
1. High-resolution images
Photos can dominate PDF size, especially when they are stored at much higher resolution than the final viewing or printing workflow needs. Downsampling reduces pixel count; image compression reduces how much data those pixels require. Some compression modes are lossy, so quality can change permanently.
2. Scanned pages
A scan often stores each page primarily as an image. Color mode, DPI, paper size and compression settings all affect file size. A 300–600 DPI color scan can be dramatically larger than a properly optimized grayscale or black-and-white scan of the same paper document.
3. Embedded fonts
PDFs can embed fonts so text renders as intended even when the recipient does not have those fonts installed. That improves portability, but embedded font data takes space. Removing or subsetting fonts can reduce size, but careless changes can alter appearance or text behavior.
4. Attachments, forms and extra objects
PDFs can contain more than visible pages: file attachments, thumbnails, comments, forms, multimedia, metadata, unused objects and layers may all contribute. Professional optimizers can audit how much space different categories use before removing anything.
Will splitting a PDF make it smaller?
Each resulting file can be smaller because it contains fewer pages, but splitting does not necessarily optimize the content of those pages. If a single page contains a 20 MB scan, extracting that page will still leave you with a large file.
Need only part of a large PDF?
eggPDF does not currently offer a dedicated compression tool. If your goal is simply to keep fewer pages, Split or Extract may solve the practical problem without pretending to optimize image quality.
Related guides
Sources
We prefer standards bodies, platform documentation and first-party technical sources for factual claims.