QuillBot AI Humanizer vs Grammarly AI Humanizer Pricing

QuillBot and Grammarly both give away an AI humanizer and both sell an AI detector. QuillBot's free tier caps each pass at 125 words and lifts that on Premium with "No word or usage limit". Grammarly's is free to its Free, Plus and Pro users but never publishes the allowance as a number, and its page states outright that the tool "is not intended to bypass AI detectors". If your writing simply reads stiff, either is worth the zero dollars. If a checker sits at the end of your pipeline, neither company is selling you that, and both say so in their own words.

This is a buying decision people get wrong in a specific way: they compare output quality when the thing that will actually decide it is a word cap and a data-handling notice. So this comparison starts with the numbers each vendor publishes, and flags every place a vendor declines to publish one.

QuillBot AI humanizer vs Grammarly humanizer pricing, side by side

Everything in this table was read on the vendor's own page on August 20, 2026.

The 125-word cap decides more of this than quality does

QuillBot publishes its free limit, which is more than most of this market does, and the number is small. It is also two limits rather than one, which we work through on the QuillBot AI humanizer page. A 2,000-word article is sixteen separate passes. That matters beyond the clicking, because each pass rewrites in isolation: the tool has no view of the paragraph before or the paragraph after, so register drifts between blocks and the seams show. Uniform rhythm is the property AI detectors measure most reliably, and stitched output can end up more uniform, not less, because every block gets pulled toward the same middle.

Grammarly does not publish a free number at all, which is a different problem. You find the ceiling by hitting it, usually in the middle of something. Between a small published cap and an unpublished one, the published cap is easier to plan around, and Premium removing it entirely is the cleanest thing on either vendor's pricing page.

Which one changes the text more?

Grammarly, if you use the part people skip. The default rewrite on both tools is a polish: shorter sentences, fewer stock connectives, a warmer register. Grammarly's custom voice is the exception, because it targets a sample of your own writing rather than a generic preset. Feed it 200 words you wrote before you ever used an AI tool and the rewrite has something specific to aim at.

That distinction matters more than it sounds. Detectors are not looking for a fingerprint; they are measuring how predictable and how even the prose is. Matching your own uneven rhythm moves those numbers further than matching an average one. The mechanism, including why swapping synonyms one sentence at a time almost never helps, is laid out in how AI detectors work.

Does QuillBot or Grammarly bypass Turnitin?

Neither company claims it, and one of them explicitly rules it out. Grammarly's page says the tool "is not intended to bypass AI detectors" and adds that "the use of AI humanizers can be frowned upon in certain contexts". QuillBot makes no bypass claim either: it returns a Human score, and its own FAQ heading asks whether you should worry when that score is not 100 percent.

Nobody outside Turnitin can verify a Turnitin pass rate anyway. Turnitin sells to institutions rather than individuals, exposes no public API, and states that it trains against rewriting tools while refusing to name them, specifically so that no vendor can find out whether it is on the list. Every confident bypass percentage in this market was produced by the company selling the tool, on a test nobody else can repeat. QuillBot's own exposure to this is covered in does Turnitin detect QuillBot paraphrasing.

The honest mechanism is smaller and more useful than a percentage. GPTZero states in its FAQ that its classifier "is not trained to identify AI-generated text after it has been heavily modified after generation". Heavy editing moves a text out of the distribution a classifier learned. A light polish does not. That is the whole of it, and it is why a free one-click pass so often changes nothing about the score.

Both of them also sell you the checker

This is the strangest thing about comparing these two products and almost nobody says it out loud. QuillBot ships an AI detector. Grammarly ships an AI detector and Authorship, which records the writing process itself. So in both cases the company selling you the rewrite also sells your reader the tool that scores it.

None of that is dishonest, and it does not make either humanizer worse. It does mean a Grammarly humanizer output scored by a Grammarly detector proves nothing, and it explains why both companies word their humanizer pages so carefully. It is also worth knowing how well the detector half performs before you lean on it: Grammarly's detector page claims 99 percent accuracy while stating on the same page that "No AI detector is 100% accurate", and PCWorld ran a Gemini-written story through it and reported 37 percent, twice. The fuller picture, Authorship included, is on the best AI humanizer for Grammarly page.

Which should you buy?

Four situations cover almost everyone.

You already pay for Grammarly. Use the Humanizer that comes with it, build the custom voice, and buy nothing else. It runs where you already write, and for unstiffening a report or an email it is the cheapest correct answer available to you.

You paste long documents and hate the caps. QuillBot Premium at $8.33 a month billed annually removes the word and usage limit outright, and that is a clean fix for a specific, measurable annoyance. Our own read of the wider QuillBot picture is on the QuillBot alternative page.

The text is confidential. Check the data notice before the feature list. OpenAI's own humanizer inside ChatGPT carries the line that chats may be reviewed and used to improve its models. If the draft is a client deliverable or unreleased research, that single sentence settles the choice regardless of output quality.

A detector sits at the end of your pipeline. Then you are shopping outside these two, because they have told you this is not the job. That is the case we make on the Grammarly AI humanizer page, and the paid field is compared on price, allowance and data handling on the best AI humanizer page. Our own plans start at $9 a month for 15,000 words, with our own AI-pattern score on screen. We save every run to your account history so you can come back to it, and every run has a delete button; the details are on our privacy page.

When neither is the right purchase

Sometimes the rewrite is not the problem. A humanizer changes rhythm and register; it does not add evidence, repair a thin argument, or check a fact. Run a draft with an invented citation through any tool on this page and you get the same invented citation in better prose, which is worse, because it now reads convincingly.

If what you actually need is writing that was good in the first place, the money goes somewhere else entirely. For a one-off piece that has to land, briefing a vetted freelance writer costs more per word and removes the problem instead of smoothing it. For anything going in front of an academic checker, the durable answer has never been a tool at all: it is a record of how the document was written, which is why version history and dated drafts settle disputes that no score ever will.

The short version

QuillBot is the better free tool if you want control and a visible number, and Premium at $8.33 a month billed annually buys off the only hard limit it publishes. Grammarly is the better free tool if you already pay for it, write in more than one language, or will actually build the custom voice. Both are readability products sold by companies that also sell detectors, both say as much in their own careful wording, and neither is trying to win the argument people are really having when they search for a humanizer.