GPT-5.1 vs Grammarly
A detailed comparison to help you choose the right AI tool for your needs.
Our Pick
GPT-5.1 Instant
GPT-5.1 Instant edges out Grammarly with superior overall performance and features that make it the better choice for most users.
Try GPT-5.1Feature Comparison
Feature
GPT-5.1
Grammarly
Ratings
Overall Rating
4.7
4.6
Coding
4.5
-
Writing
4.6
4.8
Reasoning
4.8
4.0
Speed
4.8
5.0
Value
4.6
4.5
Pricing
Monthly Price
$20
$12
Free Tier
Input (per 1M tokens)
$2.5
-
Output (per 1M tokens)
$10
-
Features
Context Window
128K
50K
Vision/Images
Audio
Video
Code Generation
AI Agents
GPT-5.1 Instant
Pros
- Fast responses with adaptive reasoning
- New personalization presets
- Strong math and coding improvements
- Multimodal (text, image, audio)
- Free tier available
Cons
- Coding not as strong as Claude Opus
- Can be verbose
- Writing style less natural than Claude
Grammarly
Pros
- Works everywhere (browser, desktop, mobile)
- Excellent grammar and spelling
- Tone detection
- Plagiarism checker
- GrammarlyGO AI assistant
Cons
- Not for creative writing
- Premium features require subscription
- Can be overly corrective
Choose GPT-5.1 if you need:
General assistant, math problems, quick coding help
Choose Grammarly if you need:
Grammar checking, professional emails, academic writing
Ready to get started?
Both tools offer free tiers or trials. Try them out and see which one works best for your workflow.