Grants.gov Attachments: File Names, Formats and Size

A federal grant application on Grants.gov can be rejected for reasons that have nothing to do with the project itself: a file name that's too long, a character the system doesn't accept, or two attachments with the same name. According to the Grants.gov applicant FAQs (checked in September 2026), attachment names should be 50 characters or fewer, use only a specific set of characters, and every attachment needs a unique name. Formats and size limits are set by each agency in its instructions.

This guide covers the rules Grants.gov publishes and a workflow for turning your narrative, budget and supporting documents into clean attachments.

What Grants.gov says about attachments

File names

• Limit file names to 50 or fewer characters.
• Use only these characters: A–Z, a–z, 0–9, underscore, hyphen, space, period, parentheses, curly braces, square brackets, ampersand, tilde, exclamation point, comma, semicolon, apostrophe, at sign, number sign, dollar sign, percent sign, plus sign and equal sign.
• Grants.gov warns that if these guidelines aren't followed, your application may be rejected.

The "Encountering Error Messages" page is stricter. It recommends avoiding special characters and spaces entirely, and using underscores instead (for example, my_Attached_File.pdf). Following that stricter advice satisfies both pages.

Duplicate names

If two or more attachments in one submission have the same name, Grants.gov says the application cannot be processed without manual intervention. Give every file a distinct name, even across different forms.

Formats and size

• Each agency sets its own restrictions on attachment types (for example, .pdf, .xls or .docx) and file sizes for each opportunity. Your Notice of Funding Opportunity (NOFO) is the rule that applies to you.
• Grants.gov suggests keeping the entire application package, including all attachments, to 200 MB. Agencies may set different limits.
• When using PDF forms, attach documents only with the form's own Add Attachment buttons.

A naming scheme that always passes

Use short, descriptive names with letters, numbers and underscores only:

• Project_Narrative.pdf
• Budget_Justification.pdf
• Letters_of_Support.pdf
• Key_Personnel_Bios.pdf
• Indirect_Cost_Agreement.pdf

Add a short prefix if you're submitting several applications, such as NSF_Project_Narrative.pdf, and check the length stays at 50 characters or fewer.

Step by step

1. Read the NOFO's formatting section. Note the required format (most agencies ask for PDF), page limits, font rules and any size limit. The agency's rules override general advice.
2. Convert your documents to PDF. Export from your word processor with "Save as PDF" (Word, LibreOffice and Google Docs all have it). If you only have a .docx file, the ConvertirDocs Online Word editor opens it and saves it as PDF through your browser's print dialog. Check the PDF, especially if you're close to a page limit.
3. Combine where the agency expects one file. Letters of support, biosketches or CVs are often requested as a single attachment. Merge PDF combines them in the order you choose, without recompressing pages. Merge runs in your browser.
4. Remove security. Signed letters sometimes arrive as protected PDFs. If you have the right to use them, Unlock PDF removes the password and owner restrictions after you type the password. It doesn't crack passwords. Also check your agency's instructions on secured files.
5. Watch the total size. If scanned letters or figures make a file heavy, Compress PDF recompresses only the images and leaves text and vector graphics untouched, so text stays sharp and selectable.
6. Rename and double-check. Apply your naming scheme, make sure no two files share a name, and count the characters.
7. Attach using the form's buttons. Then open each attachment from inside the package to confirm it's the right file.

Page limits and formatting

Page limits come from the agency, not Grants.gov. Count pages in the final PDF, not in your word processor. Headers, reference lists and appendices may or may not count, depending on the NOFO. If you need to cut pages from a combined file, remove only whole sections, and keep the order the agency asks for.

Keep a clean master folder

Before you attach anything, create one folder with only the final files, already renamed. Remove drafts, earlier versions and files with the same name from other applications. Attaching from a clean folder is the easiest way to avoid sending Project_Narrative_old.pdf by mistake, or two files with identical names.

Common mistakes

• Long, descriptive file names, such as Final_Revised_Project_Narrative_v7_after_director_review.pdf. Too long and unclear.
• Two files called Attachment1.pdf, one for each form. Duplicate names stop automatic processing.
• Special characters from your computer's defaults, such as #, /, * or accented letters.
• Word files where the NOFO asks for PDF.
• Oversized scanned appendices that push the package toward the suggested 200 MB total.

If Grants.gov rejects the package

Read the error message. It usually names the problem. File name length and characters are the most common, and both are quick to fix. Rename, re-attach, and submit again well before the deadline, because validation and agency processing can take time.

Checklist

• NOFO format, page and size rules noted.
• All attachments in the required format (usually PDF).
• Unique names, 50 characters or fewer, with safe characters.
• Total package within the agency limit and the 200 MB suggestion.
• Every attachment opened and checked inside the package.