Pick Grammarly if…
you write all day across email, docs and chat apps and want errors and tone caught without stopping to paste anything.
They overlap on rewriting, and that's where people compare them. Grammarly checks your writing in real time, everywhere you type, and adds tone detection and AI rewrites. ChatGPT rewrites, drafts and explains whenever you paste text in or ask, and it does far more besides. Its AI rewrites, though, are generic and rule-bound next to a full LLM. What it still offers is checking that happens automatically while you write.
Keep Grammarly if you want mistakes and tone flagged automatically as you write. The free plan covers that, and Pro is cheaper billed annually than at its $30/mo monthly price. Use ChatGPT (free, or Plus at $20/mo) if you'd rather paste text in for rewrites and also want an assistant for everything else.
| App | Free tier | Paid from | Top plan | Best for |
|---|---|---|---|---|
| Grammarly | Yes | $30/mo | $30/mo | Non-native and casual writers who want real-time grammar, tone, and clarity fixes everywhere they type |
| ChatGPT | Yes | $8/mo | $500/mo | Everyday writing, brainstorming, image generation, casual coding |
Monthly prices in US dollars before tax, from each vendor's official pricing (US list price; weekly-billed plans converted to a monthly figure). Updated November 2, 2026
| Grammarly | ChatGPT | |
|---|---|---|
| How it works | Real-time checks wherever you type | On request: paste text or ask in chat |
| Free tier | Grammar & spelling, tone detector, 100 AI prompts/mo | GPT-6 Luna, unlimited text chats |
| Paid plan | Pro: full-sentence rewrites, 2,000 AI prompts/mo | Plus: GPT-6.1 Sol, Deep Research, custom GPTs |
| Checks | Pro: plagiarism and AI-text detection | Not a plagiarism or AI-text checker |
| Beyond writing | Writing only | Images, voice, file analysis, coding |
you write all day across email, docs and chat apps and want errors and tone caught without stopping to paste anything.
you mostly need drafts and rewrites on demand, and want the same subscription for research, images and code.
For rewriting, largely yes, and ChatGPT's free plan has unlimited text chat. What it doesn't replace is Grammarly's automatic, real-time checking as you type, or the plagiarism and AI-text detection in Grammarly Pro.
At monthly list prices, ChatGPT Plus ($20/mo) is cheaper than Grammarly Pro ($30/mo). Billed annually, Grammarly Pro costs less than Plus.
Yes. Real-time grammar and spelling checks, the tone detector and 100 AI prompts a month are free.
How we choose: prices come from each vendor's official pricing page and are re-checked every week. We take no affiliate fees, so rankings aren't for sale.