Mary Shelley was about 18–19 years old when she wrote Frankenstein , and 19 when she completed it.

Quick Scoop: How old was Mary Shelley when she wrote Frankenstein?

If you’ve ever looked at Frankenstein and thought, “No way someone young wrote this,” you’re not alone. The core fact, though, is surprisingly simple:

  • Mary Shelley began writing Frankenstein at about 18 years old.
  • She completed the novel when she was about 19 years old.
  • The book was first published in 1818, when she was around 20.

So when people ask “how old was Mary Shelley when she wrote Frankenstein ,” the most accurate short answer is:

She started it at 18 and finished it at 19.

Tiny bit of context

  • Mary Shelley was born on 30 August 1797 in London.
  • The famous ghost-story gathering at Lake Geneva with Percy Bysshe Shelley and Lord Byron, which sparked the idea for Frankenstein , happened in 1816, when she was still a teenager.
  • The novel that came out of that challenge— Frankenstein; or, The Modern Prometheus —became one of the most influential works in Gothic and early science fiction literature.

A lot of forum and “Today I Learned” discussions latch onto this age detail because it’s striking: a teenage writer creating a book that would echo through centuries.

Why this is a trending/“TIL” style topic

On forums and social platforms, you’ll often see posts framed like:

“TIL Mary Shelley was only 19 when she completed Frankenstein.”

These posts usually spark reactions like:

  • People comparing their own age and achievements to hers (often jokingly calling themselves “failures”).
  • Others pointing out she started at 18, emphasizing how early the creative spark hit.
  • Some discussions expand into how environment, privilege, tragedy, and intense intellectual circles shaped her early life and writing.

This keeps the question “how old was Mary Shelley when she wrote Frankenstein ” circulating as a mini-trivia and inspiration point in modern “latest news” or “forum discussion” style posts.

Mini timeline (age vs. Frankenstein)

[3][5][7][9][1] [7][10] [10][4][6][2] [7][10]
Year Mary Shelley’s age What was happening?
1797 0 Mary Shelley is born in London.
1816 18–19 “Year without a summer” in Geneva; she conceives and starts writing Frankenstein.
1817 19 She completes the manuscript of Frankenstein.
1818 20 First edition of Frankenstein is published anonymously.

TL;DR

Mary Shelley started writing Frankenstein at about 18 and finished it at 19; it was published when she was around 20.

Information gathered from public forums or data available on the internet and portrayed here.