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October 2026 review · same 50 texts

Undetectable.ai vs WriteHuman

In the October 2026 HumanizerEval review, Undetectable.ai and WriteHuman rewrote the same 50 English texts. Undetectable.ai cleared all 6 detectors on 1 of them; WriteHuman on 0. The difference is mostly Pangram: on 12 samples Undetectable.ai passed it where WriteHuman failed, and the reverse happened on 5. On GPTZero, Originality.ai Turbo, Originality.ai 5.0, ZeroGPT and Winston AI the two were close to even.

Per-sample agreement

Per-sample agreement, October 2026. Counts are out of the 50 shared samples, computed at the 50% human-score threshold. Margin counts the samples only one tool passed, higher count first.
DetectorPassed more oftenMarginBoth passedNeither passed
Pangram 4.1Undetectable.ai12 to 5825
GPTZero 2026-10-07-baseWriteHuman4 to 2413
Originality.ai TurboWriteHuman1 to 0490
Originality.ai 5.0 model-5.0WriteHuman3 to 2045
ZeroGPT defaultUndetectable.ai2 to 0480
Winston AI 5.0Tied0 to 0500
All 6 detectorsUndetectable.ai1 to 0049

Every count is computed from scores.csv at build time, not transcribed. “Neither passed” counts the texts that defeated both tools; on Pangram that was 25 of 50 here.

Quality and output discipline

Quality and output discipline, October 2026.
MeasureUndetectable.aiWriteHuman
32%38%
28%50%
90%98%
60%50%
1.271.06
110
00
University / General Writing / More Human, v11srAPI default
Websiteundetectable.ai writehuman.ai

On per-sample quality scores, Undetectable.ai scored higher on 14 samples, WriteHuman on 26, and the two tied on 10. WriteHuman’s output was shorter on 46 of 50 samples; mean length ratios were 1.27 and 1.06, or 27% longer than the input and 6% longer than the input respectively.

Where each one outperforms the other

Undetectable.ai

  • Pangram: passed 20 of 50 against 13, including 12 samples where WriteHuman failed, against 5 the other way.
  • GPTZero: passed 2 samples where WriteHuman failed, even though it was detected more often overall, passing 43 to 45.
  • Originality.ai 5.0: passed 2 samples where WriteHuman failed, even though it was detected more often overall, passing 2 to 3.
  • ZeroGPT: passed 50 of 50 against 48, including 2 samples where WriteHuman failed, against 0 the other way.
  • Stance preservation: 60% against 50%.

WriteHuman

  • Pangram: passed 5 samples where Undetectable.ai failed, even though it was detected more often overall, passing 13 to 20.
  • GPTZero: passed 45 of 50 against 43, including 4 samples where Undetectable.ai failed, against 2 the other way.
  • Originality.ai Turbo: passed 50 of 50 against 49, including 1 sample where Undetectable.ai failed, against 0 the other way.
  • Originality.ai 5.0: passed 3 of 50 against 2, including 3 samples where Undetectable.ai failed, against 2 the other way.
  • Winston AI: tied at 50 of 50 but on a higher mean human score, 99.6% to 98.5%. It passed 0 samples where Undetectable.ai failed.
  • Factual consistency: 38% against 32%.
  • Naturalness: 50% against 28%.
  • Syntax integrity: 98% against 90%.
  • Length: shorter output on 46 of 50 samples, which matters under a word limit.

Undetectable.ai vs WriteHuman FAQ

Is Undetectable.ai better than WriteHuman?

In the October 2026 HumanizerEval review, Undetectable.ai cleared all 6 detectors on 1 of the 50 shared samples and WriteHuman on 0. On GPTZero, Originality.ai Turbo, Originality.ai 5.0, ZeroGPT and Winston AI the two were within 6 points of each other. Quality ran 14 samples to 26, with 10 ties.

Which humanizer is best for Pangram, Undetectable.ai or WriteHuman?

Undetectable.ai. In October 2026, Undetectable.ai passed Pangram on 20 of the 50 shared samples and WriteHuman on 13. On 12 samples Undetectable.ai passed where WriteHuman failed; the reverse happened on 5. Both failed on 25.

Which humanizer changes the text less?

WriteHuman. It scored higher on per-sample quality on 26 of 50 samples, against 14. Undetectable.ai’s outputs averaged 1.27× the input length and passed factual consistency on 32%; WriteHuman’s averaged 1.06× and passed on 38%. On stance preservation the split was 60% to 50%. WriteHuman produced the shorter output on 46 of 50 samples.

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