Fact · Voice and AI
1,000characters
OpenAI said its AI text classifier was very unreliable on short texts, below 1,000 characters.
Checked against its source on October 17, 2026
In the source's own words
“The classifier is very unreliable on short texts (below 1,000 characters).”
New AI classifier for indicating AI-written text (OpenAI, January 31, 2023, with July 2023 update), Jan Hendrik Kirchner et al., OpenAI, 2023, Limitations section of the post.
Open the original- What it measures
- OpenAI also wrote that the classifier should not be used as a primary decision-making tool, but as a complement to other methods of determining the source of a piece of text.
- What it does not show
- This is the company's own warning about its early tool. Detectors built since 2023 may set different length limits, so check the vendor's current documentation before relying on any length figure.