They’re often compared as if they do the same job. They don’t. Here’s what each one is built for, what it really costs, and what independent research says about how well it works.
Evidence review of official pricing pages, privacy policies and peer-reviewed studies, checked 14–15 Oct 2026. Hyptor Lab’s hands-on test (20 texts with known errors) is scheduled. No affiliate links. How we test
The short answer
Choose Grammarly to correct and polish what you wrote; choose QuillBot to reword it. QuillBot Premium is about 31% cheaper per year — and research shows Grammarly still misses about half of the issues humans catch.
Grammarly Pro: $144/yr · QuillBot Premium: $99.95/yr · Use both free tiers first · Confidence: Medium — prices verified; independent quality research is limited and mostly on free tiers.
What they claim vs what the evidence shows
| Their claim | Verdict | What the evidence shows |
|---|---|---|
| Grammarly: “Write without spelling and grammar mistakes” [2] | Overstated | A 2026 peer-reviewed study found Grammarly’s suggestions highly precise, but its recall was 51% — it “failed to identify almost half of the sentence-level issues” in 53 essays [8]. |
| Grammarly: organisations “save an average of $5,000 per employee per year” [10] | Untested | A vendor figure with no independent verification we could find. |
| QuillBot: helps “rewrite, edit, and change the tone of their text to improve clarity” [12] | Holds, with caveats | Small studies found QuillBot useful for paraphrasing and, in one test, better than free Grammarly at grammar checks [13][14] — but samples were small and used free tiers. |
Why this matters
Students and non-native writers often pay for one of these tools believing it will catch every error. Knowing what each is actually designed for — and how much it misses — saves money and embarrassment.
How we built this verdict
Prices and limits come from Grammarly’s plans and support pages [1][2] and QuillBot’s pricing and help pages [3][4]. QuillBot blocked automated access, so its figures were read from Wayback Machine copies dated 2–12 Oct 2026 — check the live price before buying. Quality evidence comes from three academic studies [8][13][14].
They’re built for different jobs
Finding: Grammarly’s free tier is designed around correction [2]. QuillBot’s free limits are designed around paraphrasing: 125 words per paraphrase free, unlimited on Premium, plus a summarizer and a plagiarism checker (25,000 words/month on Premium) [4].
In practice: if your problem is mistakes, start with Grammarly; if it’s awkward phrasing or rewording sources, start with QuillBot.
Grammarly is precise, but misses about half the issues
Finding: researchers compared Grammarly with two human annotators on 53 argumentative essays by second-language writers. When Grammarly flagged something, it was usually right — but its recall was 51% [8].
In practice: a clean Grammarly report doesn’t mean a clean essay. Still proofread — or ask a person.
The surprise: QuillBot beat free Grammarly in one study
A small study of ESL diploma students’ writing found QuillBot’s grammar checker outperformed the free versions of Grammarly and Ginger, though the author advises it “should be used to supplement and not replace teacher feedback” [13]. A 2025 study of 52 students found the reverse strength profile: Grammarly gave “the most comprehensive feedback” while QuillBot provided “valuable paraphrasing support” [14].
What they really cost
| Plan | Price | Key limits |
|---|---|---|
| Grammarly Free | $0 | 100 AI prompts/month; spelling and grammar |
| Grammarly Pro | $30/mo, $60/quarter or $144/yr ($12/mo) | 2,000 prompts/month; rewrites; plagiarism and AI detection; 7-day trial |
| QuillBot Free | $0 | 125-word paraphrases; 1,200-word summaries; no plagiarism checker |
| QuillBot Premium | $19.95/mo, $39.95/quarter, $79.95/6 mo or $99.95/yr ($8.33/mo) | Unlimited paraphrasing, 9 modes; 25,000 words/month plagiarism checks |
Privacy: both train on your text unless you opt out
Grammarly’s parent company — now Superhuman Platform Inc. (formerly Grammarly) — says “we also use information we collect to train our AI models”, with a setting to opt out [5][15]. QuillBot (owned by Learneo, formerly Course Hero [6][7]) says inputs are used for training and that storing inputs is “on by default”, except for Team Plan users [9]. Both say they don’t sell your content or let third-party AI providers train on it [9][15].
Which should you choose?
Grammarly if: you mainly need error correction and tone suggestions across email and documents. QuillBot if: you mainly reword, summarise or need a cheaper plagiarism checker. Neither paid plan if: the free tiers cover you — test them first. Students: check your institution’s rules on paraphrasing tools.
Questions people ask
Is QuillBot better than Grammarly?
For paraphrasing, QuillBot is the specialist; for correction, Grammarly. One small study found QuillBot’s grammar checker beat free Grammarly [13], but evidence on paid tiers is lacking.
Is Grammarly Premium worth it?
At $144/year it adds rewrites, more AI prompts and plagiarism/AI checks [1][2]. Remember it still missed about half of issues in a peer-reviewed test [8]; try the 7-day trial first.
Can you use QuillBot and Grammarly together?
Yes — many people paraphrase in QuillBot and proofread in Grammarly. Both free tiers are enough to see if that workflow suits you.
The verdict
Grammarly and QuillBot overlap less than their marketing suggests, and neither replaces a careful human read. The decision: match the tool to the job, start free, and only pay for the one you use every week.
Change log
15 Oct 2026 — Published as an evidence review. Hyptor Lab hands-on test scheduled.
Sources
- Grammarly Support, “How much does Grammarly Pro cost?”, accessed 14 Oct 2026 — support.grammarly.com
- Grammarly Plans, accessed 14 Oct 2026 — grammarly.com
- QuillBot pricing page, Wayback snapshot 2 Oct 2026 — web.archive.org
- QuillBot Help, free vs Premium, Wayback snapshot 4 Oct 2026 — web.archive.org
- Superhuman Platform Inc., Privacy Policy (effective 6 Jul 2026) — superhuman.com
- QuillBot privacy page, Wayback snapshot 1 Oct 2026 — web.archive.org
- Learneo, “Introducing Learneo”, 14 Dec 2022 — learneo.com
- Koltovskaia, Saeli & Rahmati, “An inquiry into Grammarly’s precision and recall”, Journal of Second Language Writing, 2026 — doi.org
- QuillBot Trust Center, Wayback snapshot 10 Aug 2026 — web.archive.org
- Grammarly homepage, accessed 15 Oct 2026 — grammarly.com
- QuillBot homepage, Wayback snapshot 6 Oct 2026 — web.archive.org
- QuillBot Paraphrasing Tool, Wayback snapshot 12 Oct 2026 — web.archive.org
- Ho Chui Chui, “The QuillBot Grammar Checker: Friend or Foe of ESL Student Writers?”, CPLT 10(1) — journal.uitm.edu.my
- “Enhancing EFL Students’ Recount Writing: A Comparative Analysis of Grammarly, QuillBot, and GrammarCheck”, JEAPCO, 12 Jul 2025 — polije.ac.id
- Grammarly Trust, accessed 15 Oct 2026 — grammarly.com
Right of reply
Grammarly/Superhuman and QuillBot can respond via our contact page.