"How many sources do I need?" is one of the most asked questions on every student forum. The honest answer is: it depends on the word count, level, and subject — but there are reliable rules of thumb that work across most contexts.
The short answer
| Essay length | Typical source range |
|---|---|
| 500–800 words | 3–6 sources |
| 1,000 words | 5–8 sources |
| 1,500 words | 7–12 sources |
| 2,000 words | 8–15 sources |
| 3,000 words | 12–20 sources |
| 5,000 words | 18–30 sources |
| Dissertation (10,000+ words) | 40–80+ sources |
These are starting points, not strict rules. A focused essay on a narrow topic may use fewer sources from a concentrated area of the literature; a broad comparative essay may need more.
Why source count matters (and why it's not the main thing)
Source count signals engagement with the literature, but markers are looking at something deeper: whether you are using sources to make an argument.
An essay that cites 20 sources superficially — "X argued this (Smith, 2019). Y argued that (Jones, 2021). Z suggested something else (Brown, 2022)..." — scores lower than an essay with 10 sources that are genuinely integrated into a line of argument. Padding a bibliography does not improve an essay.
The useful question is not "do I have enough sources?" but "does every source I've cited support a specific claim in the body?"
By academic level
GCSE and IGCSE
Most GCSE essays are written in timed exam conditions and do not require formal citations. For coursework, 4–8 sources is typically sufficient. At this level, the expectation is that you can demonstrate understanding of evidence — not a mastery of the academic literature.
A-Level
A-Level essays — both coursework and extended essays (EPQ, IB Extended Essay) — expect 8–15 sources for substantial pieces. The expectation is that sources include academic texts (journals, scholarly books) rather than only textbooks. A-Level history coursework might cite primary sources, secondary academic sources, and historiographical debate material.
Undergraduate university
This is where source expectations are most variable. The general principle:
- 1,000-word essays: 5–8 sources
- 2,000-word essays: 8–15 sources
- 3,000-word essays: 12–20 sources
- Dissertations: 40–80+ sources depending on the discipline
Check the assignment brief and marking rubric first — some departments specify minimum source counts. Some assignment briefs explicitly state a required number; others leave it to judgement.
Postgraduate (Masters, PhD)
Postgraduate work expects engagement with the full field. An MA dissertation of 15,000 words might cite 80–120 sources; a literature review chapter in a PhD might systematically cover hundreds of papers. At this level, the question is less "how many sources?" and more "does your bibliography demonstrate command of the relevant literature?"
By subject
Source expectations vary significantly between disciplines:
Sciences and medicine: Primary research papers are the main source type. Literature reviews may cite 30–100 papers per 5,000 words. Textbooks are secondary sources used for background, not as primary evidence.
Social sciences: Mix of peer-reviewed journals, reports, and policy documents. Statistical sources (ONS, Pew, national datasets) count. 10–20 sources per 2,000–3,000 words is typical.
Humanities (English, History, Philosophy): Mix of primary texts, academic books (monographs), and journal articles. A history essay might cite 3 primary sources and 8 secondary academic sources for 2,000 words.
Law: Case law, statutes, and academic commentary. Citations are heavy and specific. An essay may cite 20 cases and 10 academic sources in 2,000 words.
Business and management: Mix of academic journals, reports, and industry statistics. 10–15 sources for a 2,000-word essay is typical.
What counts as an academic source?
| Source type | Counts? | Notes |
|---|---|---|
| Peer-reviewed journal article | Yes | The gold standard for evidence |
| Academic book (monograph) | Yes | Good for theory and background |
| Edited academic book chapter | Yes | Cite the chapter, not just the book |
| Government statistics (ONS, BLS, etc.) | Yes | Cite the specific dataset |
| Published report (Pew, IPCC, etc.) | Yes | Note the publishing organisation |
| Newspaper article | Sometimes | Only for primary sources / examples of discourse, not academic claims |
| Textbook | Sometimes | Good for definitions; weak as primary evidence |
| Wikipedia | No | Useful for orientation; not citable |
| General websites / blogs | No | Not unless the site is an authoritative institution |
| ChatGPT / AI output | No | AI is not a citable source |
The per-paragraph check
The practical way to audit your sources is to read each body paragraph and ask: is there at least one in-text citation that supports the main claim of this paragraph? If any paragraph makes a factual or analytical claim with no citation, that is where you need to add a source.
Aim for at least one citation per paragraph. Two to three citations per paragraph is normal for a well-evidenced piece; more than four in a single short paragraph may mean you are writing a literature survey rather than an argument.
How to find more sources quickly
If you are short on sources, the most efficient routes are:
- Google Scholar — search the key terms of your argument; filter by year if you need recent work
- Backward chaining — find one strong paper, then check its bibliography for related work
- Your university library database — JSTOR, PsycINFO, EBSCO, depending on your subject
- Cite a cite — if a claim is widely made in your literature, find the original source it traces back to
For a full guide on locating academic sources, see How to Find Academic Sources. For formatting your bibliography correctly, use the Citation Reference Formatter.
Plan your essay before you write a single word
Use the free Essay Structure Planner to build your argument outline, map PEEL paragraphs, and structure your introduction and conclusion — then take the free Academic Writing Fundamentals course for the complete essay-writing system.