Grammarly has shifted from a grammar-checking browser extension to an AI writing platform, and its pricing now reflects that: the free plan includes a monthly AI-prompt allowance, not just spell-check. Pro multiplies that allowance twentyfold and adds the rewriting and plagiarism-detection tools most people associate with “real” Grammarly, but its $12-a-month headline price only applies if you pay for the full year upfront.
Get Grammarly: Visit the official Grammarly plans page →
At a Glance
| Plan | Price | AI Prompts/Month | Best For |
|---|---|---|---|
| Free | $0/mo | 100 per user | Basic mistake-checking and tone awareness |
| Pro | $12/mo billed annually ($144/yr); $20/mo quarterly; $30/mo monthly* | 2,000 per member | Full rewrites, plagiarism checks, style guides, up to 149 members |
| Enterprise | Contact sales | Unlimited per member | SSO, SCIM, custom roles, audit logs, large organizations |
*Grammarly’s own pricing page lists Pro at a flat $12 without specifying the billing cycle; the monthly/quarterly/annual breakdown above comes from a third-party pricing analysis and reflects Grammarly’s long-standing billing structure rather than a figure confirmed directly on the current official pricing page.
Short Verdict
Grammarly Free is still a genuinely useful spell- and grammar-checker with basic tone detection and a real, if modest, monthly AI allowance. Pro’s value case rests almost entirely on two things: full-sentence rewrites that go beyond flagging errors, and plagiarism detection, which Free doesn’t offer at all. If you write occasionally and don’t need either, Free remains a reasonable stopping point. If you’re drafting professionally every day, the jump to Pro’s 2,000 monthly AI prompts and rewrite tools pays for itself quickly — just pay annually, since the monthly plan costs 2.5 times as much per month.
What It Is
Grammarly is a writing assistant available as a browser extension, desktop app, mobile keyboard, and plugins for Microsoft Word and Google Docs. It checks grammar, spelling, and punctuation in real time, flags tone, and — on paid tiers — rewrites full sentences and paragraphs rather than just pointing out individual errors. It works across most text fields on the web, not only inside its own app.
Free vs. Pro: What Actually Changes
- Tone: Free shows you your writing’s detected tone. Pro and Enterprise let you actively adjust it to a target tone.
- Rewriting: Free sticks to flagging individual mistakes. Pro adds full-sentence rewrites, fluency suggestions for non-native English writers, inclusive-language checks, citation consistency checks, and AI-generated text detection.
- Plagiarism detection: Not available on Free at all. Included on both Pro and Enterprise.
- AI prompts: Free gets 100 per month; Pro gets 2,000 per member per month; Enterprise is unlimited per member.
- Style guides and brand tones: Free has none. Pro allows one of each; Enterprise is unlimited — relevant mainly to teams maintaining consistent brand voice across writers.
- Admin and security controls: Pro adds account roles/permissions and basic team analytics. Enterprise layers on SAML SSO, SCIM, custom roles, data loss prevention, an Audit Logs API, and session timeout controls.
Pro is listed as available to both individuals and “eligible teams” up to 149 members, which blurs what used to be a separate Business tier — Grammarly’s current pricing page shows only Free, Pro, and Enterprise, with no standalone Business plan listed.
Pros
- Free plan includes a real monthly AI-prompt allowance, not just basic spell-check.
- Works across most of the web through its browser extension, not locked to one writing app.
- Pro’s annual price works out to $12/month — among the cheaper premium AI writing tools when paid yearly.
- Enterprise’s unlimited AI prompts and SSO/SCIM support make it a realistic fit for large, security-conscious organizations.
Cons
- Plagiarism detection, one of Grammarly’s signature features, is completely absent from the free plan.
- Monthly billing on Pro costs $30/month versus $12/month paid annually — a 2.5x markup for flexibility.
- No separate, clearly priced Business tier anymore; teams are funneled into either Pro or a sales conversation for Enterprise.
- 100 AI prompts a month on Free is easy to exhaust if you lean on tone adjustment or rewrite suggestions regularly.
Who It’s a Good Fit For
Students, casual bloggers, and anyone writing occasional emails will likely find Free sufficient for catching mechanical errors. Professional writers, marketers, and anyone submitting work where plagiarism checks or full-sentence rewrites matter should budget for Pro, paid annually to avoid the monthly-billing markup.
Who Should Look Elsewhere
Writers who mainly want a general-purpose AI drafting and editing assistant, rather than a grammar layer on top of writing they’ve already done, may get more value from a general AI writing tool like ChatGPT Plus (covered in this site’s AI writing assistant roundup) — Grammarly is built to refine existing text, not generate long-form drafts from a prompt.
Bottom Line
Grammarly’s free plan is more capable than it used to be thanks to its built-in AI allowance, but plagiarism detection and full-sentence rewriting still require Pro. At $12/month paid annually it’s a reasonable upgrade for regular writers — just avoid the $30/month billing option unless you genuinely need the flexibility.
How Grammarly Compares to ProWritingAid
The single biggest difference between the two is plagiarism detection: Grammarly includes it on Pro ($12/month billed annually) and Enterprise, while ProWritingAid doesn’t bundle plagiarism checking into any plan at all — it’s sold separately as pay-per-use Story Credits, even on its top Premium Pro tier. ProWritingAid’s entry paid tier, Premium, is cheaper than Grammarly Pro at $10/month billed yearly ($120/year) versus Grammarly’s $12/month ($144/year), and it removes Grammarly Free’s 100-AI-prompt ceiling with unlimited line-editing runs and rewrites (ProWritingAid calls these “Rephrases”). ProWritingAid’s Premium Pro tier, at $12/month billed yearly, matches Grammarly Pro’s price almost exactly, but spends that parity on community features — live workshops, critique sessions, cowriting sprints — rather than Grammarly’s plagiarism and team-admin tools. ProWritingAid also offers a one-time lifetime purchase ($399 for Premium, $699 for Premium Pro) that Grammarly doesn’t offer in any form; Grammarly is subscription-only. Free-tier limits differ too: Grammarly Free allows 100 AI prompts a month with no document-length cap, while ProWritingAid Free caps each editing report at 500 words.
| Spec | Grammarly | ProWritingAid |
|---|---|---|
| Plagiarism detection | Included on Pro and Enterprise | Not included on any plan — sold separately |
| Entry paid price | $12/mo billed annually ($144/yr) | $10/mo billed yearly ($120/yr, Premium) |
| Free-tier limit | 100 AI prompts/month, no length cap | 500 words per editing report |
| One-time purchase option | None — subscription only | Lifetime: $399 (Premium) or $699 (Premium Pro) |
| Best for | Teams needing plagiarism checks and admin controls | Long-form writers wanting a one-time purchase and community features |
Frequently Asked Questions
- Is Grammarly free forever? Yes — the free plan never expires, including its 100 monthly AI prompts, but it never adds plagiarism detection or full-sentence rewrites no matter how long you use it.
- Does Grammarly work with Microsoft Word and Google Docs? Yes — Grammarly ships as plugins for both, alongside its browser extension, desktop app, and mobile keyboard, on every plan including Free.
- Is Grammarly worth it if I only need basic spelling and grammar checks? Probably not — Free already covers mechanical error-checking and tone detection, so there’s no need to pay unless you specifically want plagiarism detection or full-sentence rewrites.
- Is Grammarly or ProWritingAid cheaper for plagiarism checking? Grammarly, by a clear margin — it’s bundled into the $12/month Pro plan, while ProWritingAid doesn’t include plagiarism checking in any subscription tier and charges for it separately.
Sources
- Grammarly plans and pricing (official)
- Grammarly pricing breakdown by billing cycle (eesel.ai, June 2026)
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