Research Paper Format: APA, MLA & Chicago Rules

“Research paper format” gets used to mean three different things, and conflating them is the most common source of confusion when a student or early-career researcher searches the phrase. It can mean the paper’s structure — which sections go where (Introduction, Methods, Results, Discussion) — which CASRAI covers in How to Outline a Research Paper. It can mean the citation style — how in-text citations and references are built — covered in Citation Styles and Referencing Formats. Or it can mean what this guide actually covers: the page-level formatting mechanics — margins, font, line spacing, page numbers, title page and running head conventions, heading formatting, and reference-list layout — the physical appearance of the page, independent of what the sections say or how a source is cited. This guide is scoped to that third layer only, and links out to the other two where they matter.

The Three Layers of “Research Paper Format,” Disentangled

Before the specifics, it’s worth being precise about what each layer actually controls, because a single search for “research paper format” can be looking for any of the three:

Structure (what sections exist and in what order) — the IMRaD framework, section-by-section outlining, and how that differs across an empirical paper, a humanities argument paper, and a systematic review. See How to Outline a Research Paper.
Writing process (drafting order, style/voice, revision) — see How to Write a Research Paper.
Citation style (how a source is credited, in-text and in the reference list) — which style applies to which field and what structurally differs between them. See Citation Styles and Referencing Formats.
Page-level format (this guide) — the visual layout rules: margins, font, spacing, page numbers, title page, running head, heading appearance, and reference-list layout. These rules are set by whichever style manual or journal instructions govern the paper, and they are mechanical and checklist-verifiable in a way structure and prose style aren’t.

Formatting mechanics are also not interchangeable with citation style, even though the same style guide (APA, MLA, Chicago) usually governs both. A paper can follow APA’s citation rules while getting APA’s margin or heading requirements wrong, or vice versa — they’re separate checklists inside the same manual.

Formatting Elements Every Style Shares

Across APA, MLA, and Chicago, a small set of formatting decisions recur, even though the exact values differ by style:

Element	What it controls
Margins	Space between text and the page edge, on all four sides
Font and size	Typeface and point size for body text (and often a distinct rule for notes/references)
Line spacing	Single, double, or a mixed rule (e.g., double-spaced body, single-spaced notes)
Page numbers	Placement (top-right, bottom-center) and whether the title page counts as page 1
Title page / heading block	Whether a standalone title page is required, or a running heading block on page one instead
Section headings	How different heading levels are visually distinguished (bold, italic, centered, indented)
Reference list layout	Indentation, spacing, and ordering of the final reference/bibliography section

A near-universal baseline across style manuals and journal instructions is a 1-inch margin on all sides and double-spaced body text — but “near-universal” is not “universal,” and the specific font, title-page requirement, and heading rules genuinely diverge by style. The sections below cover each major style’s actual requirements, verified against each style’s own current guidance rather than assumed from one style to another.

APA Format (7th Edition)

APA (American Psychological Association) style, now in its 7th edition, is the default for psychology, social and behavioral sciences, education, and nursing, and per APA’s own guidance is also used in natural sciences and engineering contexts. Its page-format rules are unusually explicit and split into student and professional paper versions.

Margins: 1 inch on all sides (top, bottom, left, right).
Font: APA 7 allows a defined set of options rather than mandating one: serif fonts such as 12-point Times New Roman, 11-point Georgia, or normal 10-point Computer Modern, or sans-serif fonts such as 11-point Calibri, 11-point Arial, or 10-point Lucida Sans Unicode.
Line spacing: Double-spaced throughout, including the title page, abstract, and reference list.
Title page: Required for every APA paper. The student version includes the title, author byline, affiliation, course number/name, instructor name, and assignment due date. The professional version (for publication) additionally includes a running head and author note.
Running head: This is the single most-changed rule from APA 6 to APA 7. Student papers no longer include a running head unless an instructor specifically requires one. Professional papers still require one: all-capital letters, left-aligned in the page header, no more than 50 characters including spaces and punctuation, with no “Running head:” label.
Page numbers: Top-right corner of every page, including the title page (page 1), for both student and professional papers.

Because the student/professional distinction changes which of these rules actually apply, the single most common APA formatting error is applying professional-paper rules (running head) to a student paper, or vice versa, without checking which version an instructor or venue actually requires.

MLA Format (9th Edition)

MLA (Modern Language Association) style governs literature, language, and humanities writing. Its page-format rules are simpler than APA’s and, notably, do not require a separate title page for most papers.

Margins: 1 inch on all sides.
Font: MLA 9 moved away from mandating one specific font, instead requiring a readable font with clear contrast between regular and italic type. 12-point Times New Roman remains the conventional default; 11-point Arial, Calibri, and Georgia are also accepted.
Line spacing: Double-spaced throughout — the heading block, title, every paragraph of body text, block quotations, and the Works Cited page all get the same double spacing.
Heading block (in place of a title page): One inch from the top of the first page, flush left: writer’s name, instructor’s name, course name/number, and the date, each on its own double-spaced line. The paper’s title follows on the next line, centered — with no separate title page, unless an instructor specifically requests one.
Section headings: MLA does not prescribe a specific heading format. The rule is internal consistency — whatever combination of bold, italics, and alignment is chosen for a given heading level, apply it the same way at every occurrence of that level.
Page numbers: Top-right corner, preceded by the writer’s last name (e.g., “Smith 4”), starting on the first page.

Chicago Format (18th Edition)

The Chicago Manual of Style, now in its 18th edition, splits into two citation systems — notes-bibliography (common in history and the humanities) and author-date (common in the sciences and social sciences) — but its page-format rules are largely shared across both.

Margins: At least 1 inch on all sides.
Font: A standard, readable font such as Times New Roman, Arial, or Calibri, at 12-point; a slightly smaller size for footnotes/endnotes than the main text is conventional.
Line spacing: Double-spaced body text with no extra space between paragraphs. Notes (footnotes or endnotes) and bibliography entries are each single-spaced internally, with a blank line (double space) between separate entries.
Paragraph and note indentation: Body paragraphs get a 0.5-inch first-line indent; footnotes/endnotes use the same 0.5-inch first-line indent; bibliography entries use a 0.5-inch hanging indent (the first line is flush left, subsequent lines are indented).
Page numbers: Bottom-center or top-right, roughly half an inch from the page edge. The title page, where one is used, does not carry a visible page number even though it counts in the numbering sequence.

Vancouver / AMA and Journal-Governed Formats

This is where research-paper formatting genuinely departs from the APA/MLA/Chicago model, and it’s a distinction worth being explicit about. Vancouver style (the numbered reference style used across most biomedical and clinical journals, built on the U.S. National Library of Medicine’s Citing Medicine conventions and pointed to by the International Committee of Medical Journal Editors’ (ICMJE) Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals) and AMA style (the American Medical Association’s house style, used by JAMA and the JAMA Network journals) both govern citation numbering and reference-list structure in detail, but neither functions as a standalone page-layout manual the way APA, MLA, or Chicago do.

ICMJE’s own Recommendations state plainly that page-level formatting is journal-specific: a manuscript’s title page should include the title, author information, disclaimers, funding sources, and word count, but beyond that, authors are directed to consult the target journal’s own instructions for authors for margins, font, spacing, and layout. This is a structurally different situation from APA/MLA/Chicago, where the style manual itself is the authority on page appearance. In practice, most biomedical/clinical journal submission systems specify their own house requirements — commonly something close to 1-inch margins, 12-point Times New Roman or Arial, and double spacing throughout, matching the general journal-manuscript convention — but “commonly” is not “guaranteed,” and a Vancouver/AMA-style paper’s actual formatting requirement is whatever the submitting journal’s instructions for authors say, not a fixed universal rule. Always check the specific journal before formatting a manuscript for submission under either style.

Heading Hierarchy Formatting

Section headings are a formatting decision layered on top of structure — the outline decides that a subsection exists; formatting decides how it’s visually distinguished from surrounding text. APA 7 is the most explicit style on this point, defining five distinct heading levels:

Level	Format
Level 1	Centered, Bold, Title Case — text begins as a new paragraph below it
Level 2	Flush Left, Bold, Title Case — text starts on the next line
Level 3	Flush Left, Bold Italic, Title Case — text starts on the next line
Level 4	Indented, Bold, Title Case, ending in a period — text continues on the same line
Level 5	Indented, Bold Italic, Title Case, ending in a period — text continues on the same line

MLA and Chicago don’t prescribe an equivalent fixed hierarchy — MLA explicitly leaves heading style to the writer’s discretion, and Chicago’s guidance focuses more on numbering conventions in longer works than on a fixed bold/italic ladder. The rule that carries across every style regardless of the specific format chosen: whatever visual treatment is used for a given heading level, apply it identically at every occurrence of that level throughout the paper. Inconsistent heading formatting — a Level 2 heading bolded in one section and not another — is one of the most common mechanical errors in student and early manuscript drafts, independent of which style guide is in use.

Reference List Formatting Basics (Distinct From Citation Style)

The layout of the reference list itself — as opposed to what information goes into each individual reference entry — follows its own formatting rules, and it’s worth separating from citation style specifically because the two are easy to conflate:

Indentation: APA, MLA, and Chicago (both systems) all use a hanging indent for reference-list/bibliography entries — the first line of each entry is flush left, and any subsequent lines are indented (typically 0.5 inches). Vancouver and AMA, by contrast, use a numbered list format with no hanging indent, since entries are ordered by citation number rather than alphabetically.
Ordering: APA, MLA, and Chicago’s author-date system order the reference list alphabetically by author surname. Chicago’s notes-bibliography system orders its bibliography alphabetically as well, even though in-text citations are numbered footnotes. Vancouver, AMA, and IEEE order the reference list numerically, by order of first citation in the text — not alphabetically.
Spacing: APA and MLA double-space reference-list entries, matching the body text. Chicago single-spaces individual entries but adds a blank line between entries.
Section heading: The label itself varies by style — “References” (APA, Vancouver, AMA, IEEE), “Works Cited” (MLA), or “Bibliography” / “Notes” (Chicago) — and using the wrong label for the style in use is a small but noticeable formatting error.

This is the formatting layer of the reference list — how it looks on the page. What goes inside each entry (author order, title capitalization, DOI placement) is citation-style content, not formatting, and CASRAI covers that separately: see How to Find, Cite, and Use a DOI for full worked reference examples across five styles, How to Cite a Dataset for data and software citation, and Et Al. Citation Rules for the specific author-count thresholds that trigger “et al.” in each style.

Format Requirements Change by Context

The same style’s formatting rules don’t always apply uniformly — the context a paper is produced for changes what’s actually required:

Course papers typically follow a single style manual’s student-paper version in full (e.g., APA 7 student format), as specified by the instructor or department.
Theses and dissertations are usually governed by an institution’s own graduate-school formatting guide, which frequently layers additional requirements — specific margin sizes for binding, mandatory front matter (abstract, table of contents, list of figures), and embargo/deposit formatting — on top of whichever citation style the department uses. See What Is a Dissertation? Structure, Defense, and Deposit for how that front matter and deposit process work.
Journal submissions are governed first by the target journal’s own instructions for authors, which frequently override or supplement the base citation style’s page-format conventions — margins, word limits, and figure/table placement rules are journal-specific even when the citation style itself (e.g., Vancouver) is fixed by the field. Figures specifically carry their own separate technical formatting requirements (resolution, file format, sizing) — see Scientific Figure Rules for Journal Submission.
Systematic reviews add a reporting-structure layer (PRISMA 2020) on top of standard formatting — see PRISMA and Systematic Review Methodology.

In every one of these contexts, the actual governing document — course syllabus, graduate school formatting guide, or journal’s instructions for authors — takes precedence over a style manual’s default when the two conflict. A style guide sets the baseline; the specific venue’s instructions are the final word.

Formatting Checklist Before Submission

Margins match the required style or venue (commonly 1 inch on all sides, but verify — Chicago allows “at least” 1 inch, and journal house styles vary).
Font and point size match the style’s approved options (not just “looks similar”).
Line spacing is applied consistently — including the title page, notes, and reference list, where the style requires it there too.
Page numbers are placed correctly and start where the style specifies (title page counted as page 1 in APA; MLA’s last-name-plus-number format).
The correct title-page/heading-block convention is used for the style AND the student-vs-professional distinction, where that applies (APA).
Running head is included only where actually required (APA professional papers, or when an instructor explicitly asks for one on a student paper) and stays under 50 characters.
Heading levels are formatted consistently at every occurrence, not just the first.
The reference list uses the correct indentation (hanging vs. none), ordering (alphabetical vs. numeric), and section label for the style in use.
For journal submission specifically, the target journal’s current instructions for authors have been checked directly — not assumed from the citation style alone.

Frequently Asked Questions

Is “research paper format” the same as “research paper structure”?

No. Structure is which sections exist and in what order (Introduction, Methods, Results, Discussion, etc.) — covered in CASRAI’s outlining guide. Format, as used on this page, is the page-level visual layout: margins, font, spacing, page numbers, and heading appearance. A paper can have correct structure and incorrect formatting, or vice versa — they’re independent checklists.

What is the standard margin size for a research paper?

1 inch on all sides is the near-universal default across APA, MLA, and most journal house styles. Chicago specifies “at least” 1 inch. Always confirm against the specific style edition or venue in use rather than assuming 1 inch applies everywhere without checking.

What font should I use for a research paper?

It depends on the style. APA 7 and MLA 9 both allow a defined set of serif and sans-serif options (commonly 12-point Times New Roman, or 11-point Calibri/Arial). Chicago recommends a standard 12-point font such as Times New Roman, Arial, or Calibri. For journal submission, the target journal’s instructions for authors take precedence over any style manual’s default.

Does a research paper need a title page?

APA requires one for every paper (student and professional versions differ in content). MLA does not require a separate title page — it uses a heading block on the first page instead, unless an instructor specifically requests one. Chicago typically uses a title page for longer papers but the notes-bibliography and author-date systems don’t mandate one identically across all uses.

Does every research paper need a running head?

No. Running heads are an APA-specific convention, and as of APA 7th edition, student papers no longer include one by default — only professional papers being prepared for publication require it, unless an instructor specifically asks a student to include one.

Is reference-list formatting the same as citation style?

Related, but distinct. Citation style governs what information appears in each reference entry and how in-text citations point to it. Reference-list formatting governs how the completed list looks on the page — indentation, spacing, and ordering. See CASRAI’s Citation Styles and Referencing Formats guide for the style-selection layer this page doesn’t repeat.