Why AI Detector Scores Change Across Tools

An AI detector score can look precise: 17%, 62%, mixed, likely AI. That precision is easy to overread. Most detectors are probabilistic systems, not proof machines. They look for patterns that resemble text from certain model families, then translate those patterns into a score, label, or confidence band. Change the detector, the threshold, or even the amount of surrounding text, and the result can move. Sometimes it moves a little. Sometimes it jumps enough to feel suspicious, even when the draft itself has barely changed.

Text length matters more than many writers expect. A short passage gives the detector very little context, so a few similar sentence structures can carry too much weight. A longer essay gives more signals, but it can still be affected by a template-like introduction, a repetitive methods paragraph, or a stack of formal transitions. Small edits can also redistribute probability. Removing headings, changing citations, or splitting a paragraph may alter how the system reads the whole piece.

A practical review starts away from the number. Look for three things first: sentences that are almost all the same length, transitions that announce every logical move, and paragraphs that sound fluent but do not add concrete evidence. If those issues are present, revise for clarity and texture. Add the specific example. Vary the sentence movement. Let the argument breathe where it needs a pause.