Grammarly AI Humanizer Review (2026): A Paraphraser With a New Name?
We tested Grammarly's AI Humanizer: two detectors still flagged it, including 61% AI on QuillBot's. Why it works like a paraphraser, pricing and alternatives.
Grammarly's AI Humanizer rewrites text to sound less robotic, but it works like a paraphraser, not a true humanizer. In our test, its output was still flagged as AI by two detectors, including 61% AI on QuillBot's. That's consistent with Grammarly's own positioning: the tool is built for readability and tone, not for getting past AI detectors.
Key takeaways
- Grammarly's humanizer mostly swaps words and smooths phrasing, which leaves the patterns AI detectors look for.
- In our test, HumanizerPRO's detector and QuillBot's detector (61% AI) both still flagged the output.
- Grammarly says the feature isn't meant to bypass AI detectors, so don't use it for that.
- It's useful for polishing tone and readability, especially if you already pay for Grammarly Pro.
What is Grammarly's AI Humanizer?
Grammarly is one of the most widely used writing tools in the world, known for grammar, spelling and clarity suggestions. Its AI Humanizer is a newer feature that rewrites text, including AI-generated drafts, to make it read more naturally.
Basic humanization is available on the free tier. In our September 2026 test, though, the free humanizer's output still scored 100% AI on GPTZero, which labeled it AI paraphrasing (see the full free humanizer test). With a Grammarly account, you can choose from preset voices, create a personal voice profile and use several languages, and Grammarly Pro unlocks the full version. Rather than counting words, Grammarly meters its generative features in "prompts": free users get 100 a month and Pro subscribers get 2,000.
The key point is that Grammarly says the humanizer is there to make text read better and sound more pleasant, not to beat AI checkers. Plenty of people try it for exactly that reason anyway, so we tested it.
How we tested it
The HumanizerPRO team tested Grammarly's AI Humanizer in August 2025, using a simple process:
- Generate sample text with an AI model.
- Run it through Grammarly's AI Humanizer.
- Check the output with two AI detectors: the HumanizerPRO AI detector and QuillBot's AI detector.
We used the same method in our QuillBot humanizer test, so the results are comparable.
Test results: still flagged as AI
The humanized text didn't make it past either of the detectors.
The rewrite made the text different from the original, but not different enough in the ways detectors measure. That's the typical result for tools that paraphrase rather than rewrite, and it's the same pattern we saw with QuillBot and Rewritify.
Why Grammarly's humanizer is really a paraphraser
A paraphraser swaps words and lightly reorders sentences while keeping their structure. A humanizer rebuilds the text: it varies sentence length and rhythm, restructures paragraphs and replaces predictable phrasing, all while keeping the meaning.
Grammarly's output looks a lot like what a paraphraser produces: different words, same skeleton. Detectors like GPTZero and Turnitin don't care much about individual words. They look at how predictable the text is and how evenly its sentences are built, which we explain in how AI detectors actually work. If the skeleton stays, the AI score stays. For the full comparison, see AI humanizers vs. paraphrasing tools.
Pricing
The humanizer isn't sold on its own. You get it through Grammarly's plans:
| Plan | Price | Generative AI allowance |
|---|---|---|
| Free | $0 | 100 prompts a month, basic humanization |
| Pro | $12/month billed yearly, $30 month to month | 2,000 prompts a month, full humanizer |
| Enterprise | Custom | Custom |
If you already pay for Grammarly Pro, it's a nice extra when you want to soften the tone of a section. We wouldn't pay for Pro just for the humanizer if your only goal is getting past AI detection. If you want Pro-style rewriting and AI checks without paying, see our list of the best free Grammarly alternatives.
Grammarly AI Humanizer vs. HumanizerPRO
We make HumanizerPRO, so keep that in mind when reading this comparison.
| Grammarly AI Humanizer | HumanizerPRO | |
|---|---|---|
| Built for | Readability and tone | Rewriting AI text to read as human |
| Rewrite depth | Word swaps and light restructuring | Paragraph-by-paragraph rewrite with fine-tuned models |
| AI detection in our test | Flagged by both detectors | Includes its own AI detector to check results |
| Free use | Basic humanization, 100 AI prompts a month | 500 words without an account, 1,000 words a month with one |
| Best for | Polishing grammar and tone | AI drafts that need to sound human |
A practical way to use both: run your draft through an AI humanizer first, then use Grammarly for a final grammar and clarity check. You can humanize a draft with HumanizerPRO for free and compare the two outputs on the same detector.
Who should use Grammarly's AI Humanizer?
Good for: light editing, fixing clunky phrasing, making your tone sound more natural, and people who already use Grammarly every day.
Not good for: getting text past AI detectors, academic work checked with Turnitin, or published content that has to read as clearly human-written.
Final verdict
Grammarly's AI Humanizer is a decent polishing tool with a misleading name. It improves readability, but in our test its output was still flagged as AI, and Grammarly doesn't claim otherwise. If you need AI text that reads as human, use a dedicated humanizer and check the result. Our best AI humanizers list compares the options.
Frequently asked questions
Does Grammarly have an AI humanizer?
Yes. Grammarly's AI Humanizer rewrites text to make it sound more natural and easier to read. The free plan includes a limited version, and Grammarly Pro unlocks the full feature.
Can Grammarly's humanizer bypass AI detectors?
Not in our test. Its output was still flagged as AI by HumanizerPRO's detector and scored 61% AI on QuillBot's. Grammarly also says the feature isn't intended to bypass AI detectors.
Is Grammarly's AI Humanizer free?
The basic humanizer is free, and the full version is included with Grammarly Pro, which costs $12 a month billed yearly or $30 a month.
Is Grammarly's humanizer better than QuillBot's?
The results are remarkably similar. Both work more like capable paraphrasers than true humanizers, and neither passed the AI detectors in our tests. QuillBot has a separate free humanizer page, while Grammarly's is one piece of a wider writing assistant.
Is it ethical to use an AI humanizer?
It depends on how you use it and the rules you're under. Using one to improve the readability of your own AI-assisted writing is ordinary editing. Using one to hide AI use where it's banned, such as in a class that prohibits AI, breaks that rule.
What's the best free alternative to Grammarly's AI Humanizer?
HumanizerPRO (humanizerpro.ai) is a free AI humanizer with a built-in AI detector, plagiarism checker and fact checker. It rewrites text paragraph by paragraph with fine-tuned models, offers tones such as academic, casual and business, and lets you humanize 500 words without an account or 1,000 words a month with a free account.
Kamran Khan
Kamran Khan is the founder of HumanizerPRO and a leading voice in the ethical use of AI-generated content. With years of hands-on experience in AI, SEO, and digital publishing, he built HumanizerPRO to help creators and professionals turn robotic AI text into clear, human-like writing that meets real-world standards.