TL;DR
The Grammarly vs ProWritingAid question splits on manuscript length. ProWritingAid
Premium ($10/mo annual, $120/yr — or $399 lifetime) is built for long-form authors:
25+ document-wide reports, Scrivener support, one payment. Grammarly Pro ($12/mo
annual, $144/yr; $30 month-to-month) is the better everyday editor — instant corrections
in every app, a free tier you can actually live on, plagiarism detection included.
Book writers should buy ProWritingAid; everyone else starts free on Grammarly.
The contenders
- Grammarly (now part of Superhuman) checks grammar, spelling, tone, and clarity everywhere you type — browser, desktop, mobile, Docs, Word. Its old Premium tier is now Pro (1–149 seats), and the old Business plan folded into it.
- ProWritingAid is a manuscript-analysis suite: solid line editing plus 25+ reports (pacing, echoes, sticky sentences, dialogue tags) that read your whole document, aimed squarely at novelists and long-form writers.
Pricing as of October 2026 (grammarly.com/plans, prowritingaid.com/pricing):
| Plan | Grammarly | ProWritingAid |
|---|---|---|
| Free | Basic grammar, tone detection, 100 AI prompts/mo | 500 words at a time, 2 report runs/day, 10 rephrases/day |
| Paid, monthly | Pro: $30/mo ($60 per quarter) | Premium: $30/mo; Premium Pro: $36/mo |
| Paid, annual | Pro: $12/mo ($144/yr) | Premium: $10/mo ($120/yr); Premium Pro: $12/mo ($144/yr) |
| Lifetime | — | Premium $399; Premium Pro $699, one-time |
| Plagiarism check | Included in Pro | Additional cost on every tier |
| Other | Enterprise: contact sales, unlimited prompts | Student 20% off; K-12 free; Story Credits sold separately |
ProWritingAid Premium is 17% cheaper per year ($120 vs $144), and its $399 lifetime
license breaks even against Grammarly Pro in about 2.8 years ($399 ÷ $144) — after
that, your editing costs nothing. Grammarly is subscription-only; there is no way to buy
it once.
Evidence and scope
Both tools were re-checked against their official pricing and feature pages on October 4,
- Every price, quota and limit below comes from the vendors' own pages. We did not run a blind or seeded-error test for this article; earlier draft accuracy figures and scores have been removed.
Grammarly vs ProWritingAid side by side
| Dimension | Grammarly Pro | ProWritingAid Premium |
|---|---|---|
| Annual cost | $144/yr | $120/yr (or $399 lifetime) |
| Free-tier ceiling | Unlimited basic checks, 100 AI prompts/mo | 500 words/check, 2 report runs/day |
| Correction speed | Instant, inline, everywhere you type | Good inline; reports run on demand |
| Whole-document analysis | Sentence-by-sentence plus one overall score | 25+ reports across the full document |
| AI assistance | 2,000 prompts/mo, full-sentence rewrites | Unlimited rephrases; 5 Sparks/day (50/day on Pro) |
| Plagiarism | Included | Paid add-on |
| Integrations | Browser, desktop, mobile, Docs, Word | Docs, Word, Scrivener, Vellum, Chrome/Edge/Firefox |
| Fiction-aware reports | None | Dialogue tags, pacing, sensory detail |
ProWritingAid's distinguishing scope: it is the only one of the two that reports on the
document as a whole, flagging sentence-length plateaus, repeated echoes, and pacing dips
Grammarly never mentions. Its weakness is the free tier: 500 words at a time makes a real
evaluation awkward, while Grammarly's free plan works all day.
Where Grammarly wins
- Corrections where you type: inline suggestions in every app you use — browser, desktop, mobile, Docs, Word.
- Coverage: email, Slack, CMS, Docs, mobile keyboard — one checker across the OS.
- Free tier: unlimited basic grammar, spelling, and tone feedback plus 100 AI prompts a month.
- Bundled extras: plagiarism and AI-text detection sit inside Pro; ProWritingAid charges extra for plagiarism on every tier.
- Teams: Pro carries style guides, brand tones, snippets, and analytics for up to 149 seats.
Where ProWritingAid wins
- Depth: 25+ reports (pacing, echoes, sticky sentences, overused words, dialogue tags) diagnose the whole manuscript — Grammarly works one sentence at a time.
- Lifetime license: $399 once (Premium Pro $699) versus renting Grammarly at $144/yr forever.
- Price: $120/yr annual, 17% below Grammarly Pro.
- Author tooling: Desktop Everywhere runs reports inside Scrivener, Vellum, and Word; Grammarly has never supported Scrivener.
- Writer extras: author comparison, custom style guide, daily Chapter Critique, discounted Story Credits, 20% student discount.
Who should pick what
Pick Grammarly if…
- Your writing lives in email, Docs, Slack, and CMS posts — short-form, everywhere.
- You want a free tool with no word caps that holds up for daily use.
- You need plagiarism and AI detection included rather than as an add-on.
- You run a team and want style guides, brand tones, and seat analytics.
Pick ProWritingAid if…
- You are writing a book, thesis, or any 5,000+ word piece where structure matters.
- You want to see patterns — rhythm, repetition, pacing — not just corrections.
- You work in Scrivener or Vellum and refuse to copy-paste chapters into a web box.
- You plan to write for years: $399 once beats $144 a year after about 2.8 years.
Buy both if…
- Editing is your livelihood. Grammarly Pro during drafting ($144/yr) plus ProWritingAid Premium for the structural pass ($120/yr) is $264/yr combined — less than one hour of a human editor, and the tools cover different stages of the same manuscript.
The bottom line
Grammarly vs ProWritingAid is not a quality contest; it is a stage-of-writing choice.
Drafting, email, and everything short: Grammarly, free or $144/yr. Manuscript editing,
deep reports, and a lifetime horizon: ProWritingAid at $120/yr or $399 once.
Verdict: ProWritingAid for long-form authors; Grammarly for everyday writers
If you are producing a book or any document where structure, pacing, and repetition
decide whether it reads well, ProWritingAid is the editor that earns the money — its
reports show what sentence-by-sentence checking cannot, and the $399 lifetime option means
you never think about the bill again. If your writing is the work around the book —
emails, docs, posts, client work — Grammarly's free tier already covers you, and Pro is
worth $144/yr the day you need plagiarism checks, tone control, or team style guides.ProWritingAid Premium $120/yr or $399 lifetime; Grammarly Pro $144/yr — 25+ whole-document reports vs instant everywhere-editing.
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