> ## Documentation Index
> Fetch the complete documentation index at: https://payperfax.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# File Requirements

> Supported file formats, size limits, and technical specifications

PayPerFax accepts multiple file formats for faxing. Learn about the requirements and best practices for preparing your documents.

## Supported file formats

<CardGroup cols={4}>
  <Card title="PDF" icon="file-pdf" color="#DC2626">
    **Recommended**

    Most reliable format
  </Card>

  <Card title="DOC/DOCX" icon="file-word" color="#2563EB">
    **Word Documents**

    Microsoft Word files
  </Card>

  <Card title="TIF/TIFF" icon="file-image" color="#7C3AED">
    **Image Format**

    G3 compression supported
  </Card>

  <Card title="JPG/JPEG" icon="file-image" color="#16A34A">
    **Photo Format**

    Image files
  </Card>
</CardGroup>

## File size limits

<Warning>
  **Maximum file size**: 8MB per upload

  Files larger than 8MB will be rejected.
</Warning>

<Tip>
  If you have a large document, consider:

  * Compressing the PDF
  * Splitting into multiple faxes
  * Reducing image quality/resolution before converting to PDF
</Tip>

## How to attach files

<Steps>
  <Step title="Click 'Choose files'">
    On the PayPerFax web form, click the "Choose files" button
  </Step>

  <Step title="Select your file">
    Browse your computer and select a file to upload
  </Step>

  <Step title="Add more files (optional)">
    Click "Choose files" again to add additional documents

    Files will be faxed in the order you added them
  </Step>
</Steps>

<Info>
  You can attach multiple files. They'll be combined into a single fax in the order uploaded.
</Info>

## Format recommendations

<AccordionGroup>
  <Accordion title="PDF - Best choice" icon="file-pdf">
    **Why PDF is best**:

    * Most consistent conversion to fax format
    * Preserves layout and formatting
    * Works well with both text and images
    * Widely compatible

    **Tips**:

    * Use black text on white background when possible
    * Avoid complex graphics or colored backgrounds
    * Test that text is readable at lower resolution
  </Accordion>

  <Accordion title="DOC/DOCX - Good for text" icon="file-word">
    **Microsoft Word documents work well for**:

    * Text-heavy documents
    * Simple formatting
    * Letters and forms

    **Cautions**:

    * Complex layouts may not convert perfectly
    * Fonts may be substituted
    * Embedded images should be high contrast

    <Tip>
      If your Word document has critical formatting, convert it to PDF first and review before faxing.
    </Tip>
  </Accordion>

  <Accordion title="TIF/TIFF - Native fax format" icon="file-image">
    **TIFF is the native fax format**:

    * G3 compression supported
    * Black and white only
    * Direct transmission without conversion

    **When to use**:

    * You already have fax-format files
    * Receiving faxes electronically and forwarding them
    * Maximum compatibility required
  </Accordion>

  <Accordion title="JPG/JPEG - For scanned documents" icon="file-image">
    **JPEG works for**:

    * Scanned documents
    * Photos (though faxes are black & white)
    * Images of forms or papers

    **Tips**:

    * Use high contrast (dark text, light background)
    * Ensure text is sharp and readable
    * Remember that colors will convert to grayscale
  </Accordion>
</AccordionGroup>

## Technical specifications

<Accordion title="Processing details" icon="gears">
  When you upload a file, PayPerFax:

  1. **Validates** the file format and size
  2. **Converts** to fax format (TIFF G3)
  3. **Processes** at fine quality: 204×196 dpi
  4. **Converts** to black and white (1-bit)
  5. **Generates** preview for your review

  This takes 30-60 seconds depending on document complexity.
</Accordion>

<Accordion title="Resolution: 204×196 dpi" icon="image">
  Faxes use standard resolution of 204×196 dpi (lower than typical documents). This is the universal fax standard worldwide and why faxes appear pixelated on screens.

  See [Why Confirmations Look Low Quality](/troubleshooting/low-quality-confirmations) for complete details.
</Accordion>

<Accordion title="Black and white only" icon="palette">
  Fax technology transmits in **1-bit black and white** (not grayscale).

  **Color conversion**:

  * Colors are converted to grayscale first
  * Then converted to pure black or white (dithering)
  * Light colors may disappear
  * Dark colors become black

  <Warning>
    Avoid colored text on colored backgrounds - it may become unreadable.
  </Warning>
</Accordion>

## Preparing documents for faxing

<Steps>
  <Step title="Use high contrast">
    * Black or dark text
    * White or very light background
    * Avoid gray text or watermarks
  </Step>

  <Step title="Keep layouts simple">
    * Standard margins
    * Single column when possible
    * Avoid tiny fonts (12pt minimum recommended)
  </Step>

  <Step title="Test before faxing">
    * Convert to grayscale on your computer
    * Zoom out to simulate lower resolution
    * Verify all text is readable
  </Step>

  <Step title="Combine multiple files">
    If you have multiple documents:

    * Either upload them separately (faxed in order)
    * Or combine into a single PDF first
  </Step>
</Steps>

## Common file issues

<AccordionGroup>
  <Accordion title="File too large (over 8MB)" icon="triangle-exclamation">
    **Solutions**:

    * Compress the PDF using online tools or Adobe Acrobat
    * Reduce image quality in your PDF
    * Split into multiple smaller faxes
    * Remove unnecessary pages
  </Accordion>

  <Accordion title="Document looks different after processing" icon="eye">
    **This is normal**: Fax format has lower resolution than modern documents.

    * Text should still be readable
    * Layout may shift slightly
    * Fine details may be lost

    Use the preview to verify readability before sending.
  </Accordion>

  <Accordion title="Colored document becomes unreadable" icon="palette">
    **Problem**: Light colored text or backgrounds disappear

    **Solution**: Convert to high-contrast black-on-white before faxing
  </Accordion>

  <Accordion title="File format not accepted" icon="ban">
    **Not supported**:

    * EPS, AI (vector graphics)
    * PSD (Photoshop)
    * RAW image formats
    * Compressed archives (ZIP, RAR)

    **Solution**: Convert to PDF, DOCX, or export as JPEG/TIFF
  </Accordion>
</AccordionGroup>

## Multiple file handling

When you attach multiple files:

1. **Order matters**: Files are faxed in the order you added them
2. **Combined into one fax**: All files become a single transmission
3. **Total page count**: All pages from all files are summed for pricing
4. **Preview shows all**: The preview displays the complete combined fax

<Tip>
  If you need to change the order of files, you'll need to start over and upload them in the correct sequence.
</Tip>

## Minimum requirements

<Warning>
  You must provide either:

  * At least one attached file, OR
  * A cover page, OR
  * Both

  You cannot send a completely empty fax.
</Warning>

## Related topics

<CardGroup cols={2}>
  <Card title="Step-by-Step Guide" icon="list-check" href="/sending-faxes/step-by-step-guide">
    Complete sending instructions
  </Card>

  <Card title="Step-by-Step Guide" icon="list-check" href="/sending-faxes/step-by-step-guide">
    Review your converted document
  </Card>

  <Card title="Low Quality Confirmations" icon="image" href="/troubleshooting/low-quality-confirmations">
    Why faxes appear pixelated
  </Card>

  <Card title="Cover Pages" icon="file-lines" href="/sending-faxes/cover-pages">
    Add a text cover page
  </Card>
</CardGroup>