NIH Application Formatting Requirements: A 2026 Checklist

NIH applications can be withdrawn before peer review for formatting violations alone. The rules are mechanical and specific: 11-point minimum font, no more than 15 characters per linear inch, no more than six lines per vertical inch, at least half-inch margins on all sides with no applicant content inside them, letter-size paper or smaller, unencrypted PDFs, and filenames of 50 characters or fewer. This checklist covers each one, with the exact threshold and the reason it exists.

These requirements apply to attachments across your application, and NIH notes they are most heavily scrutinized in attachments that carry page limits.

Font, density, and spacing

Rule	Requirement
Font size	11 points or larger
Type density	No more than 15 characters per linear inch, including spaces
Line spacing	No more than six lines per vertical inch
Text color	No restriction; black or high-contrast recommended for legibility

Smaller text inside figures, graphs, diagrams, and charts is acceptable as long as it remains legible when the page is viewed at 100%.

NIH recommends Arial, Georgia, Helvetica, and Palatino Linotype, though other serif and non-serif fonts are acceptable if they meet the size, density, spacing, and color requirements.

One failure mode worth naming, because it defeats careful writers: some PDF conversion software silently reduces font size during export. A document that was compliant in your word processor can become noncompliant in the PDF you actually submit. Confirm the final PDF — not the source file.

Margins and page setup

Provide at least one-half inch margins on the top, bottom, left, and right of every page. No applicant-supplied information may appear in the margins — that includes headers, footers, PI name, and page numbers. Pagination is system-generated; the submission system adds page numbers, PI name, and document title automatically.

Paper size must be no larger than standard letter (8.5" × 11"). Both portrait and landscape are accepted, though landscape can be harder to read on screen and may force reviewers to scroll.

Filenames

Use descriptive, unique filenames of 50 characters or fewer, including spaces. Use one space between words, not two or more, and avoid ampersands and other special characters.

This is among the easiest rules to violate and the easiest to check — a long descriptive filename that reads perfectly well can exceed the limit without anyone noticing.

PDF requirements

All uploaded documents must be PDFs, and the submission system must be able to open and edit them to assemble your application image. That means disable all security features — do not encrypt or password-protect any document.

Avoid scanning text documents to produce PDFs. Produce documents in your word processing software and convert them directly. Scanning can hamper automated processing. Scanning is understood to be necessary in some cases, such as signed letters of support on letterhead.

For SciENcv-generated biosketches, do not flatten the PDF. SciENcv use became mandatory for biographical sketches as of January 25, 2026, and a flattened biosketch PDF will be rejected.

Page limits and their order of precedence

Page limits are not defined in one place, and the order matters. When sources disagree:

1. A page limit stated in a related NIH Guide notice takes precedence over both other sources.
2. A page limit in the funding opportunity takes precedence over the Table of Page Limits.
3. Otherwise, follow the Table of Page Limits.

If no page limit appears in the Table of Page Limits, in Section IV of the funding opportunity under Page Limitations, or in a Guide notice, the attachment is generally not page-limited.

Rules that are easy to miss

Hyperlinks. Use hyperlinks only where NIH requests them, or in relevant citations and publication lists in biosketches. Do not use hyperlinks elsewhere in the application.

Resubmissions. Do not use bracketing, indenting, highlighting, bolding, italicizing, underlining, margin lines, or changes in typography, font, or font color to mark changes in a resubmission. Describe changes in the Introduction instead.

Data Management and Sharing Plans are subject to the same formatting requirements as the rest of the application, including font size and margins — and are at risk of causing a withdrawal if they aren't compliant.

Why these rules carry disproportionate risk

NIH staff conduct an administrative review that checks font style, type size, page limits, and margin size, and noncompliant applications may be withdrawn from review and funding consideration. That withdrawal happens before peer review — meaning a formatting error stops your application before anyone reads the science.

It's worth being clear about what the submission portal does and doesn't do here. Passing eRA Commons or Grants.gov validations confirms the system received a file that passed its automated checks. It does not confirm your application is compliant and safe to enter review — a distinction NIH itself has warned applicants about. NIH also notes that line-based limits like type density are not systematically enforced by the system, which means a violation can pass submission and surface later, when there is no time to fix it.

And there is no recovery window. The submission deadline is 5 PM local time at your organization on the due date, and correcting an on-time submission after the deadline is treated as late.

Checking these before you submit

Every rule on this page is mechanical: a threshold, a character count, a measurement. That makes them verifiable by inspection rather than judgment — which is precisely why they should never be the reason an application fails.

Recensa's package preflight checks these specific formatting and packaging rules deterministically against the published requirements — font size, type density, line spacing, margins, filename length, page limits, encryption, and file validity — and reports what it finds so you can fix it while there's still time. It does not evaluate your science, and it does not replace your institution's submission review. See what we check and how.

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Requirements verified against NIH guidance as of July 2026. NIH updates formatting and forms requirements between cycles — always confirm against the current application guide and your specific funding opportunity, which can impose stricter requirements than the general rules above.