📄 PDF Size & Compression Calculator
Estimate exported PDF size before you click Save. Helps avoid the classic 800 MB print-to-PDF failure on a mid PC.
| Strategy | Output | Quality | Meets target? |
|---|---|---|---|
| Lossless (ZIP / Flate) | 23.63 MB | 100% | no |
| JPEG q80 images | 11.82 MB | ~85% | no |
| Downsample images to 150 DPI | 8.44 MB | ~80% (web) | YES |
| Aggressive (subset fonts + q60) | 5.06 MB | ~70% (email) | YES |
Model: rawBytes = pages * basePerPage[type] * (dpi/150)^2 * (color ? 3 : 1) + (embedFonts ? 2.4 MB : 0). Compression ratios are typical Flate/JBIG2 outcomes — your mileage will vary with image entropy.
How this PDF size calculator works
The model multiplies a per-page baseline (selected by content type) by the DPI scaling factor and color factor, then adds a fixed cost for embedded fonts:
rawBytes = pages * basePerPage[type] * (dpi/150)^2 * (color ? 3 : 1) + (embedFonts ? 2.4 MB : 0)Per-page baselines reflect real-world measurements: pure-text contracts run ~60 KB, mixed presentations ~220 KB, scanned pages ~1.8 MB, and vector CAD drawings ~320 KB at 150 DPI. The color factor of 3× is a typical CMYK-vs-grayscale overhead.
Compression ratios are typical outcomes for Flate (lossless), JPEG q80, downsampling to 150 DPI, and aggressive font subsetting + JPEG q60. Your actual ratio will depend on the entropy of your images.
When to use it
- PowerPoint to PDF on a mid PC just produced an 800 MB monster.
- You need to email a 200-page scanned contract and the limit is 10 MB.
- A vector CAD drawing is failing to upload to your client portal.
- You are pre-flight checking a print job before sending to a commercial printer.
Related fixes
See our PDF tools fixes for export failures, and the Print Dimension Calculator for canvas sizing.