How to use the free AI detector
- Paste your text into the box above. Anything from a paragraph to 1,500 words works, and longer samples give steadier results.
- Click Check. Within seconds you get an AI-likelihood score from each detector, shown next to each other.
- Compare the scores. If they agree, you have a clear answer. If they split, read the section below on why that happens.
- If the text scores as AI and you want it to read as yours, send it to the AI humanizer and check again.
Free use gives you 5 checks per day. Paid plans raise that to 50 checks per day, which suits teachers, editors and anyone reviewing several documents at once. Details are on the pricing page.
How to read an AI score
An AI score is a probability, not a verdict. A result of 80% AI means the detector thinks text like this is much more likely to come from an AI writer than from a person. It does not mean 80% of the sentences were written by AI, and it does not prove anything about who wrote it.
A rough way to read the numbers:
- 0 to 20%: reads as human. Most detectors would not flag it.
- 20 to 50%: mixed signals. Common for edited AI drafts, very formal writing and text by non-native writers.
- 50 to 80%: likely to be flagged by at least some detectors. Worth revising.
- 80 to 100%: strong AI patterns. Typical of unedited ChatGPT, Gemini or Copilot output.
Look at the spread as well as the average. One high score among several low ones tells you something different from every detector reading high.
What detectors actually measure
AI detectors do not compare your text to a database of AI answers. They measure patterns. The two most common are perplexity (how predictable each next word is) and burstiness (how much sentence length and structure vary). AI writers tend to choose the most likely word every time and to write sentences of similar length, so their text is low in both.
Detectors also pick up on repeated transitions ("Moreover", "Furthermore", "In conclusion"), tidy three-item lists everywhere, and stock phrases such as "delve into", "a testament to" or "in today's fast-paced world". Formatting habits like frequent em dashes and markdown headings are a giveaway to human readers, though they matter less to the scoring itself. Our AI text cleaner removes those for free.
Why scores differ between detectors
It is normal for one detector to say 95% AI and another to say 30% on the same text. Each one was trained on different examples, weighs different signals and sets its own threshold for what counts as AI. Some are tuned to catch as much AI text as possible and accept more false alarms. Others are tuned to avoid accusing people and miss more AI text.
Short text makes the gap wider. Under about 150 words there is not much pattern to measure, so scores jump around. Lists, code, tables and heavily cited passages also confuse detectors because they are repetitive by nature.
This is the reason to check several detectors at once. The school or client reviewing your work may use any one of them, so a result that is low across the board is far more reassuring than a single good score. Turnitin in particular is only available to institutions, so no public tool can show you its exact number. Our guide to Turnitin AI detection explains what it looks for.
False positives: when human writing gets flagged
Every AI detector produces false positives. Writing that is careful, formal and evenly structured can look machine-made even when a person wrote every word. The groups most often affected:
- Non-native English writers, who often use simpler, more predictable vocabulary.
- Students following strict essay templates with set topic sentences and transitions.
- Technical, legal and scientific writing, where precise standard phrasing is the norm.
- Text that went through grammar tools, which smooth out natural variation.
If your own writing is flagged, keep your drafts and version history; they are the strongest evidence of your process. Then vary sentence length, swap generic transitions for specific links between ideas, and add concrete details only you would know. If you would rather not do that by hand, the essay humanizer rewrites the text in a natural voice while keeping your arguments and citations. You are responsible for following your school's academic-integrity policy, and the tool works best for polishing your own drafts.