How long should a conclusion be?

The 5-10% rule

Conclusions run shorter than introductions because their job is smaller: no orientation needed, no question to set up — just the argument's landing. For a 1,500-word essay that's 75–150 words; for a 3,000-word paper, 150–300.

A conclusion that balloons past 10% is usually doing forbidden work: introducing new evidence, starting a fresh argument, or re-summarizing every section in order. If a point matters, it belongs in the body; the conclusion states what the body earned.

What a conclusion actually does

Two moves, occasionally three: restate the thesis in the light of the evidence presented (not verbatim), state the answer's significance — why it matters beyond this essay — and, where the genre allows, one forward-looking sentence: a limitation, an open question, an implication.

The weakest conclusions start "In conclusion" and repeat the introduction with synonyms. Markers read hundreds of those; landing the significance instead is what separates strong finishes.

Can a conclusion be one sentence?

In short-form writing, yes — a decisive closing line can outperform a paragraph. In academic essays a single-sentence conclusion reads as abrupt; aim for at least 3–4 sentences that restate, contextualize and close.

Should the conclusion repeat the introduction?

It should mirror the introduction's promise, not repeat its words. The introduction says what you'll argue; the conclusion says what the argument established and why it matters — informed by everything between.