PDF Got Bigger After Converting to B&W? How to Reduce the Size
Key points
- Pages become images, which can enlarge the file
- Lower the resolution
- Finish with Compress PDF
Convert a PDF to Grayscale turns each page into an image and makes it monochrome. So a text-based PDF can get larger.
Why it gets bigger
- A text-based PDF stores text as data, which is light.
- After conversion the whole page is an image, which is heavier.
- Conversely, a PDF that is mostly scans or photos may get smaller.
How to make it smaller
- Lower the resolution: try "Small (100 dpi)". Check readability in the preview.
- Use pure black & white: for text-only documents it is usually smaller than grayscale.
- Compress afterward: shrink the result further with Compress PDF.
- Remove unneeded pages: keep only what is needed.
Size guidance
- Email attachment limits vary by service. If too large, you can send in parts.
Caution
Lowering the resolution too far makes small text unreadable. Lower it only as far as it stays readable.
Use "Convert a PDF to Grayscale (Black & White)" (free)Tools that go well with this
- Compress PDF: Shrink a PDF to fit under a size you choose, for upload limits.
- Combine PDF Pages onto One Sheet (2-up, 4-up): Arrange several PDF pages on one A4 sheet (2, 4, 6, 8 or 9 up) to save paper when printing.
- PDF to Images: Save each page of a PDF as a JPEG or PNG image.
More guides for this tool
- How to Convert a PDF to Grayscale for Free (Works on Phones)
- Grayscale or Pure Black & White: Differences and When to Use Each
- Making Color Documents Readable in Black & White Printing
- Making a PDF Black & White Before Fax or Copying
- Making Scanned Documents Black & White: Readability vs. Size
- Troubleshooting Monochrome PDFs: Faint, Broken Text, Cannot Select Text