# How to Merge PDFs and Compress Simultaneously
Last month I helped someone merge 20 scanned contract pages into one PDF. Each scan was about 2MB, so we expected around 40MB total.
The merged file? 87MB.
Way bigger than the sum of parts. Too large to email. Took forever to open. Completely impractical.
That's when I showed them the smart approach: merge and compress in one operation. Same 20 pages, but the final file came out to 6.8MB—a 92% reduction. Perfectly emailable, fast to open, and the quality was indistinguishable from the original.
Here's the thing most people don't realize: merging PDFs without compression is like stuffing suitcases into a bigger suitcase without reorganizing anything. You end up with wasted space and unnecessary bulk.
In this guide, I'll show you exactly how to merge and compress PDFs simultaneously, using various tools from simple online options to advanced command-line scripts. You'll learn when to compress, how much to compress, and how to maintain quality while dramatically reducing file sizes.
Why Merge and Compress Together?
Doing both operations at once offers major advantages:
1. Save Time
Two-step approach:
- Merge PDFs → Get 50MB file
- Compress → Wait for processing → Get 8MB file
One-step approach:
- Merge + compress → Get 8MB file directly
You skip an entire step and the waiting time that comes with it.
2. Better Compression Ratios
When you compress during merging, the compression algorithm can optimize across all pages simultaneously. This often yields better results than compressing pre-merged documents.
3. Consistent Quality
Applying compression settings once (during merge) ensures consistent quality across all pages. Two-step processes sometimes create inconsistent results.
4. Reduced Storage I/O
You only write to disk once instead of twice, reducing wear on SSDs and speeding up the process.
5. Simplified Workflow
One command or one upload instead of two separate operations. Especially helpful for batch processing.