Fax transmissions can lose quality compared to the original document. Here's why and how to maximize legibility.
Why fax loses quality
Fax was designed in the 1980s and the standard hasn't changed dramatically since. The transmission resolution (typically 200×200 DPI, sometimes lower) is significantly less than what you see on a modern computer screen. Color is converted to monochrome. Fine details, light text, and small type can all be affected.
Additionally:
- The recipient's printer (if they print the fax) adds another quality loss.
- Long-distance transmission introduces noise that can blur edges.
- Older receiving fax machines have worse output quality than modern online fax services.
How to send the highest-quality fax
Source document:
- Use black text on white background for maximum contrast.
- Use a font size of at least 10pt for body text. 12pt or larger is safer.
- Avoid colored backgrounds, watermarks, or patterns that may be unreadable when converted to monochrome.
- Avoid handwriting in pencil if possible. Black pen is much more reliable.
- Save as PDF rather than image when possible. PDFs hold text quality better than rasterized images.
File format:
- Best: PDF generated directly from a digital source (Word, Google Docs).
- Good: PDF generated from a high-quality scan (300+ DPI scanner).
- Less good: phone photo of a document. Use a scanner app like Scan.Plus.
- Worst: low-resolution screenshot.
Common quality issues and fixes
Faded / pale output:
- Source document had light text. Increase contrast or darken text before saving.
- If the source is a photo, increase contrast and brightness in your photo editor.
Blurry text:
- Source resolution was too low. Re-scan or re-create at 300 DPI minimum.
- For photos, use a scanner app rather than the camera.
Lines or noise across the page:
- This is usually caused by transmission line noise on the recipient's side, which we can't control.
- Re-send and the issue often disappears on the second attempt.
Pages out of order:
- The recipient's machine may print pages in reverse order. This is a recipient-side setting, not a Fax.Plus issue.
Test before sending an important fax
For critical documents (legal, medical, financial), send a test to your own Fax.Plus number first. Check what arrives in your Inbox to verify exactly how the recipient will see the fax.
When the issue is on the recipient side
If your fax shows as Successful but the recipient says it's illegible:
- Ask if they're using a fax machine or an online fax service. Online services typically render quality better.
- Ask if they can request the document be re-sent (you'll receive a re-send confirmation in your Inbox if yes).
- For critical documents, offer to email the original PDF as a backup.