Grammarly vs ChatGPT: which to use for emails, essays and proofreading (and how to use both)

Know what each one is built for

Compare what they cost (checked on the official pages)

Both have a free plan that covers a lot of everyday writing. Here's what each official pricing page showed when we checked:

Prices change and can differ by country, so treat the table as a starting point and confirm on each official page before you pay.

Emails: draft in ChatGPT, send with Grammarly

For an email that matters (a complaint, a request to your manager, a reply to an upset customer), get the structure right in ChatGPT, then let Grammarly catch the small stuff in your email app.

Help me write an email to [who] about [topic].
Goal: [what I want them to do or know].
Key facts: [facts, dates, numbers].
Tone: [friendly / firm / apologetic], under [120] words, one clear ask at the end.
Ask me up to 3 questions first if anything important is missing.

Paste the draft into Gmail or Outlook, change anything that doesn't sound like you, and accept or reject Grammarly's suggestions as it underlines them. Read it once more before you hit send: neither tool knows the relationship or history behind the email the way you do.

Essays and school work: use ChatGPT as a coach, not a ghostwriter

Check your school's or teacher's AI policy first. Many allow feedback tools but not AI-written work. A safe pattern is to write the essay yourself and ask ChatGPT for feedback instead of a rewrite:

Here is my essay draft. Don't rewrite it.
1. Tell me in one sentence what my main argument is, as you understand it.
2. List the 3 biggest problems with structure or clarity, with the paragraph number.
3. Point out any claim that needs evidence or a source.
4. Ask me 2 questions that would make the argument stronger.
[paste essay]

Then fix it in your own words, and run Grammarly over the final version for grammar, punctuation and citation consistency. If your school checks for AI-generated text, keep your drafts and notes so you can show your process.

Proofreading: let Grammarly mark changes, or ask ChatGPT to list them

The risk with proofreading in a chat assistant is that it quietly rewrites more than you asked. If you use ChatGPT for it, tell it exactly that:

Proofread the text below. Fix only spelling, grammar and punctuation.
Do not change wording, tone or structure.
Return a table of every change: original | corrected | reason.
Then give the corrected text.
[paste text]

Grammarly avoids the problem by design: every suggestion is shown inline and you accept or dismiss it. For long documents, that is usually faster and safer.

Tone: describe it once, reuse it everywhere

Grammarly's Free plan shows how your writing comes across, and Pro adds one-click tone changes and full-sentence rewrites. In ChatGPT you get the same effect by describing your voice once and reusing it:

Here are 3 emails I wrote that sound like me: [paste].
Describe my writing style in 5 bullet points (sentence length, formality, words I use, words I avoid, how I open and close).
From now on, when I ask you to rewrite something, match that style.

Save that description in ChatGPT's custom instructions or personalization settings so you don't paste it every time (see our custom instructions guide).

Use both together (the 3-pass routine)

1. Think and draft in ChatGPT: brief it with the 5-part formula (role, task, context, format, constraints) from our prompt guide, and ask it to ask you questions first.
2. Make it yours: rewrite anything that sounds generic, add the specifics only you know, and delete anything you can't verify.
3. Polish with Grammarly where you send it: fix the underlined issues and check the tone before you hit send or submit.

Never paste passwords, account numbers or other people's private information into either tool, and check your employer's policy before using them on work documents.

Comparing more writing tools? See our best AI writing tools guide and Copy.ai vs Jasper vs Writesonic.