NIH proposal FAQs

page limits
https://grants.nih.gov/grants/how-to-apply-application-guide/format-and-write/page-limits.htm

Font (size, color, type density) and Line Spacing

Adherence to font size, type density, line spacing and text color requirements is necessary to ensure readability and fairness. Although font requirements apply to all attachments, they are most important and most heavily scrutinized in attachments with page limits.

Text in your attachments must follow these minimum requirements:

• Font size:  Must be 11 points or larger. Smaller text in figures, graphs, diagrams and charts is acceptable, as long as it is legible when the page is viewed at 100%.
  • Some PDF conversion software reduces font size. It is important to confirm that the final PDF document complies with the font requirements.
• Type density:  Must be no more than 15 characters per linear inch (including characters and spaces).
• Line spacing: Must be no more than six lines per vertical inch.
• Text color: No restriction. Though not required, black or other high-contrast text colors are recommended since they print well and are legible to the largest audience.

We recommended the following fonts, although other fonts (both serif and non-serif) are acceptable if they meet the above requirements.

• Arial
• Georgia
• Helvetica
• Palatino Linotype

Legibility is of paramount importance. Applications that include PDF attachments that do not conform to the minimum requirements listed above may be withdrawn from consideration.

paper and margin
https://grants.nih.gov/grants/how-to-apply-application-guide/format-and-write/format-attachments.htm#papersizeandmargins 

• Use paper size no larger than standard letter paper size (8 ½" x 11”).
• Provide at least one-half inch margins (½" ) - top, bottom, left, and right - for all pages. No applicant-supplied information can appear in the margins.