Grammarly vs ChatGPT for Writing: Do You Need Both?

I pay for both Grammarly Premium and ChatGPT Plus. Recently I started wondering if that’s stupid.

So I ran an experiment: used only ChatGPT for a week, then only Grammarly, then both together. Here’s what I learned.

What Each Tool Actually Does

Grammarly: Catches errors and suggests improvements in whatever you’re typing. Always running in the background. Browser extension + apps.

ChatGPT: Generates, rewrites, and transforms text based on what you ask. You go to it actively.

Different tools. Different jobs.

Where Grammarly Wins

Passive Error Catching

Grammarly catches stuff while I’m typing in Gmail, Docs, Slack - everywhere. I don’t have to think about it.

ChatGPT requires me to copy text, paste it, ask for proofreading, then copy the result back. More steps.

For quick emails and messages, Grammarly’s passive checking is genuinely useful.

Consistency Over Long Documents

Grammarly tracks style choices across a document. If you write “e-mail” once and “email” later, it flags it.

ChatGPT reviews whatever you give it. It doesn’t remember your style choices from the last thing you pasted.

Learning While You Work

Grammarly shows you why something’s wrong. Over time, you make fewer of those mistakes.

ChatGPT fixes things but doesn’t always explain why. Less educational.

Where ChatGPT Wins

Major Rewrites

“Make this paragraph more conversational” - ChatGPT does this dramatically better.

Grammarly makes incremental suggestions. ChatGPT can transform entire pieces.

For any significant rewriting, ChatGPT is the tool.

Writing From Scratch

Obviously, Grammarly can’t write for you. It only improves existing text.

ChatGPT can draft entire documents, brainstorm ideas, create outlines.

Different category entirely.

Voice and Tone

“Rewrite this to sound more confident” or “Make this funnier” - ChatGPT handles this.

Grammarly can suggest tone adjustments, but they’re subtle. ChatGPT can completely transform voice.

Solving Writing Problems

“I’m trying to say X but it comes out awkward” - ChatGPT can give you five alternatives.

Grammarly can only work with what you’ve written. It can’t generate options.

The Week-Long Experiment

Week 1: Only ChatGPT (No Grammarly)

What happened: I caught myself copying emails into ChatGPT just to check for typos. Annoying.

I also missed things. ChatGPT doesn’t catch everything when you ask for proofreading. I published a blog post with “their” instead of “there” because I didn’t think to have ChatGPT proofread before publishing.

Week 2: Only Grammarly (No ChatGPT)

What happened: I found myself thinking “ChatGPT would just rewrite this better” constantly.

Grammarly is great at fixing what’s there. It’s bad at helping when the whole paragraph needs rethinking.

I was spending more time trying to fix sentences when I should have just rewritten them.

Week 3: Both Together

What happened: This is clearly the best workflow.

• Grammarly catches typos and basic issues passively
• ChatGPT handles significant rewrites and transformations
• They don’t overlap much in practice

Do You Need Both?

Yes, if: You write professionally and the $12/month for Grammarly + $20/month for ChatGPT Plus is trivial for your budget.

Maybe not, if: Money is tight. In that case, prioritize ChatGPT.

Here’s my reasoning: ChatGPT can do 90% of what Grammarly does if you’re willing to paste and prompt. Grammarly can’t do what ChatGPT does at all.

If I had to pick one, ChatGPT wins easily.

The Actually Smart Setup

Minimal (free/cheap):

• Grammarly Free (catches basic errors passively)
• ChatGPT Free (handles rewrites and generation)
• Total: $0

Standard (most writers):

• Grammarly Free (basic errors)
• ChatGPT Plus (better model, faster responses)
• Total: $20/month

Full stack (professional writers):

• Grammarly Premium (advanced suggestions, clarity improvements)
• ChatGPT Plus (powerful generation/rewriting)
• Total: $32/month

Most people are fine with the Standard setup. The Grammarly Premium upgrade is the weakest link - ChatGPT handles most of those “advanced suggestions” better anyway.

My Current Setup

I kept both after the experiment, but I’m questioning Grammarly Premium specifically.

What I actually use Grammarly for:

• Catching typos in emails and Slack
• Passive checking while I write in Google Docs

What I use ChatGPT for:

• First drafts
• Major rewrites
• “Make this sound better” requests
• Any significant writing task

There’s almost no overlap. They’re genuinely complementary.

But Grammarly Premium specifically? I’m probably downgrading to free. The advanced features just duplicate what ChatGPT does better.

Bottom Line

Grammarly: Keep for passive error catching. Free tier is probably enough.

ChatGPT Plus: Worth the $20/month if you write regularly.

Both together: Makes sense, but don’t overspend on Grammarly Premium.

The marketing makes them seem like competitors. In practice, they’re different tools for different jobs. The question isn’t “which one” - it’s how much of each you need.