Bottom Line: Grammarly is the most polished writing assistant available. The free plan catches real errors (not just typos), and Premium's AI features — especially the tone detector and rewriting suggestions — are worth the $12/month for anyone who writes professionally.
What is Grammarly?
Grammarly is an AI writing assistant that checks grammar, spelling, style, clarity, and tone across virtually every place you write — from Google Docs to Gmail to Slack. With over 30 million daily users, it's the most widely deployed writing tool in the world.
In 2024 Grammarly significantly expanded its AI features — moving beyond error correction into full sentence rewrites, tone transformation, and an "Authorship" feature that detects how much of your writing is AI-generated. We tested both the free and Premium plans across multiple writing contexts.
Free vs Premium: What's the Real Difference?
Free Plan
Grammarly's free plan catches grammar errors, basic spelling mistakes, and punctuation issues. It works in 500,000+ apps via the browser extension. In our testing, it caught about 70% of the issues that Premium caught — making it genuinely useful, not just a crippled demo.
Premium Plan ($12/mo, billed annually)
Premium adds: clarity rewriting suggestions, advanced style improvements, tone detection, full-sentence rewrites, vocabulary enhancement, formality level adjustments, and a plagiarism checker (250 million documents). The AI writing suggestions in 2025 are noticeably better than 2023 — more natural, context-aware rewrites rather than mechanical corrections.
Business Plan ($15/user/mo)
Adds brand tone guidelines (so Grammarly writes in your company voice), admin controls, team analytics, and priority support. Worth it for teams of 3+.
"I've been using Grammarly Premium for 4 years and it catches things that would embarrass me in client emails every single week. It's my most-used tool by time saved."
Ratings
Pricing
| Plan | Price | Key Features |
|---|---|---|
| Free | $0 | Grammar, spelling, punctuation, browser extension, 500K+ app integrations |
| Premium ⭐ | $12/mo (annual) | +Clarity, style, tone, rewrites, vocabulary, plagiarism checker |
| Business | $15/user/mo | +Brand tone, team analytics, admin controls, SAML SSO |
Pros & Cons
- Works everywhere — 500,000+ app integrations
- Free plan is genuinely useful, not a trial
- Premium AI rewrites are natural and context-aware
- Tone detector is best-in-class
- Annual Premium is just $12/mo — excellent value
- Not a content creator (limited to editing existing text)
- Can be overly aggressive with suggestions on creative writing
- Plagiarism checker database less comprehensive than Turnitin
- Monthly billing is expensive ($30/mo vs $12/mo annual)
Final Verdict
Grammarly at $12/month (billed annually) is one of the most defensible subscriptions in this guide. It makes you a measurably better writer by catching errors before they reach clients, colleagues, or readers. The free plan is worth installing for anyone who writes. Premium is worth it for anyone who writes professionally.
Annual Premium is 60% cheaper than monthly billing. Best price is usually in November during Black Friday sales — Grammarly often offers 55–60% off annual plans. Start with Free →