The short answer
One page holds roughly 500 words single-spaced or 250 words double-spaced, assuming 12pt Times New Roman on US Letter or A4 with one-inch margins. That is the setup nearly every essay brief and manuscript guideline describes, so it is the one to assume when nobody has told you otherwise.
Why the number moves
A page is a fixed amount of space. How many words fit in it depends on how much room each word takes, and that is decided by three things:
- The font. Calibri is narrower than Times New Roman, so more of it fits. Courier New is monospaced — every letter takes the width of a capital M — so far less does.
- The point size. Going from 12pt to 14pt costs you roughly a quarter of the words on the page.
- The line spacing. This is the big one. Double spacing halves the page, exactly.
Words per page, by setup
| Font and size | Single | 1.5 lines | Double |
|---|---|---|---|
| Times New Roman 12pt | 500 | 333 | 250 |
| Arial 12pt | 470 | 313 | 235 |
| Calibri 11pt | 640 | 427 | 320 |
| Verdana 12pt | 400 | 267 | 200 |
| Comic Sans MS 12pt | 420 | 280 | 210 |
| Courier New 12pt | 350 | 233 | 175 |
What will throw it off
These figures assume solid prose. A document with a heading every few paragraphs, block quotes, a table, an image or a bibliography will run longer than its word count suggests — sometimes by a page or more over a short essay. If you are close to a page limit, check the real document rather than the estimate.
When you are given a page limit
Ask which setup, and if you cannot ask, use 12pt Times New Roman double-spaced with one-inch margins. Hitting a page target by widening the margins or switching to a 14pt font is obvious to anybody who marks for a living, and it is usually the first thing they check.