Per-File Stats
After each file completes, you see the compression results directly in the queue:
- Original size → Compressed size — e.g., "1.8 MB → 1.4 MB"
- Savings percentage — e.g., "-22%" (only shown when savings are 5% or greater)
- Dimensions — if an image was resized, you see before and after: "4000×3000 → 1280×960"
- Processing time — when available, shown as duration: "· 00:05:32"
Full format example: 1.8 MB (4000×3000) → 1.4 MB (1280×960) (-22%) · 00:05:32
Session Summary
When all files complete, the queue header shows your aggregate stats:
- Total bytes saved — e.g., "Saved 125.6 MB (35%)"
- Input/output totals — e.g., "2.3 GB → 1.5 GB"
- File count — shown in the download button: "Download All (15)"
These totals aggregate across all successfully compressed files in your batch.
How Savings Are Calculated
The savings percentage is calculated as:
Savings = (1 - CompressedSize / OriginalSize) × 100
For example, a 10 MB file compressed to 3 MB = 70% savings.
We only show savings when they're meaningful—if compression reduces size by less than 5%, we don't display a percentage. This avoids misleading "-1%" or "-2%" displays on files that were already well-optimised.
Compare Mode (Images)
For image compressions, click the Compare button on any completed file to open a side-by-side comparison:
- Draggable slider — slide left/right to reveal the before and after images
- Zoom controls — zoom in from 1x to 4x to inspect details
- Pan support — drag to move around when zoomed in
- Stats bar — shows original dimensions, compressed dimensions, and exact savings percentage
Compare Mode helps you verify that compression preserved visual quality while reducing file size.
Quality Safeguards
All our compressors include a critical safeguard: if compression would increase file size, we return the original file unchanged.
This can happen with files that are already heavily optimised or use specific encoding that doesn't compress well. You'll never get a larger file from Compress.FAST.
Processing Speed
Typical compression times vary by format and file size:
- Images — 0.1 to 2 seconds, depending on resolution
- PDFs — depends on page count and embedded image density
- Office documents — depends on embedded media complexity
Higher-tier plans get more parallel workers, so large batches complete faster. A Business user processing 100 files will finish significantly sooner than a Free user with the same batch.