0%
Risk for Grammar Checks
92%
GrammarlyGO AI Score
0%
After Humanizer
$1.45
Per Week
The Short Answer: It Depends on How You Use Grammarly
Unlike ChatGPT, Claude, or Grok, Grammarly is not primarily an AI text generator. It's a writing assistant with a spectrum of features — from basic grammar checks that are completely safe to AI-powered generation that gets caught every time. The answer to "Can Turnitin detect Grammarly?" depends entirely on which end of that spectrum you're using.
Most students use Grammarly for what it does best: fixing grammar, spelling, and punctuation. These corrections are 100% safe. They make targeted fixes to YOUR words without generating new text, so Turnitin sees no AI fingerprint whatsoever. You can use Grammarly's grammar checker on every essay with zero risk.
The problem starts when students use Grammarly's newer AI features — GrammarlyGO, full-sentence rewrites, and paragraph-level paraphrasing. These features use a large language model to generate new text, and Turnitin's AI detection engine catches LLM-generated text regardless of which model produced it.
The Most Common Mistake
Students assume ALL of Grammarly is safe because it's marketed as a "grammar tool." This was true before GrammarlyGO launched. Now Grammarly includes a full AI text generator that produces the same statistical patterns as ChatGPT. Using GrammarlyGO and assuming you're safe because "it's just Grammarly" is how students get caught.
The rest of this guide breaks down exactly which features are safe, which get caught, and how to use Grammarly's AI features without detection using humanization.
Grammar Corrections vs AI Rewriting: The Critical Difference
The key distinction is simple: does Grammarly fix your words, or generate new ones? Fixing your words is safe. Generating new text gets caught.
What's Safe
- Spell check corrections
- Grammar fixes (subject-verb agreement, tense)
- Punctuation corrections
- Basic clarity suggestions
- These fix YOUR words → 0% AI detected
What Gets Caught
- Full sentence rewrites
- Paragraph restructuring
- GrammarlyGO compose
- GrammarlyGO rewrite
- These generate NEW text → 60-95% AI detected
Why the difference matters technically: Turnitin detects statistical patterns in generated text — specifically perplexity (how predictable each word is) and burstiness (how varied sentence structures are). Grammar corrections don't change these patterns because they're making targeted fixes, not rewriting from scratch. AI generation creates entirely new text with the telltale low-perplexity, low-burstiness signature that Turnitin's classifier is trained to detect.
Grammar Fix (Safe)
Your text: "The students was struggling with there assignments." → Grammarly: "The students were struggling with their assignments." — Two words changed. Your voice, your structure, your statistical fingerprint. Turnitin sees nothing.
AI Rewrite (Caught)
Your text: "The students was struggling with there assignments." → GrammarlyGO: "Many students have been experiencing significant difficulties in completing their academic coursework and assigned tasks." — Entirely new sentence generated by an LLM. New statistical fingerprint. Turnitin flags it immediately.
This same principle applies to all paraphrasing tools that Turnitin catches — it's not about which tool you use, but whether it generates new text or edits existing text.
GrammarlyGO and AI Features: What Turnitin Actually Catches
GrammarlyGO launched as Grammarly's AI writing assistant, powered by a fine-tuned large language model. It can compose emails, rewrite paragraphs, adjust tone, and generate content from prompts. It's essentially a built-in ChatGPT competitor inside Grammarly.
And Turnitin treats it exactly the same way. GrammarlyGO output scores 85-95% AI detected on Turnitin — virtually identical to raw ChatGPT or Claude output. Turnitin's classifier doesn't care which LLM generated the text. It detects the shared statistical patterns that all transformer-based models produce: uniformly low perplexity, predictable token distributions, and flat sentence structure variance.
GrammarlyGO = AI Text Generation
Turnitin treats GrammarlyGO output the same as ChatGPT, Claude, or Gemini output. The fact that it's inside a "grammar tool" doesn't change the detection. If the text was generated by an LLM, Turnitin detects it.
The highest-risk GrammarlyGO features are "Compose" and "Rewrite". Compose generates entirely new text from a prompt — functionally identical to asking ChatGPT to write something. Rewrite takes your text and regenerates it from scratch using the LLM. Both produce text with the full AI statistical fingerprint.
For a full comparison of how Turnitin handles different AI tools, see our ChatGPT Turnitin detection analysis — the detection mechanisms are identical because the underlying technology is the same.
Detection Rates by Grammarly Feature
Here's the complete detection spectrum for every Grammarly feature. The pattern is clear: the more text Grammarly generates (rather than edits), the higher the detection rate.
| Grammarly Feature | Detection Risk | Typical AI Score | Safe? |
|---|---|---|---|
| Spell check | None | 0% | ✓ |
| Grammar correction | None | 0-2% | ✓ |
| Punctuation fixes | None | 0% | ✓ |
| Sentence clarity | Low | 5-15% | ⚠ Caution |
| Full sentence rewrite | High | 60-75% | ✗ |
| Paragraph restructure | High | 70-85% | ✗ |
| GrammarlyGO compose | Very High | 85-95% | ✗ |
| GrammarlyGO rewrite | Very High | 80-92% | ✗ |
| After humanization (any feature) | None | 0% | ✓ |
The bottom row is the key takeaway: regardless of which Grammarly feature you used, humanization drops the AI score to 0%. Whether your text was generated by GrammarlyGO compose (95%) or lightly rewritten by sentence clarity (15%), the humanizer rewrites the statistical fingerprint to produce completely undetectable text.
The 3-Step Method: Use Grammarly Without Getting Caught
You don't have to stop using Grammarly. You just need to know which features are safe and what to do after using the risky ones. Here's the method that guarantees 0% AI detection on Turnitin.
Step 1: Use Grammarly for What It Does Best
Use Grammarly freely for grammar, spelling, punctuation, and basic clarity. These features are completely safe — they fix YOUR words without generating new text. Run your essay through Grammarly's grammar checker as many times as you want. Zero detection risk.
The rule of thumb: if Grammarly is underlining errors in your text and suggesting fixes, you're safe. If Grammarly is offering to rewrite, compose, or generate text for you, proceed to Step 2.
Step 2: Humanize Any AI-Generated Text
If you used GrammarlyGO, full sentence rewrites, or heavy paraphrasing, paste the output into the StudySolutions AI Humanizer. In 15-30 seconds, the humanizer rewrites the statistical fingerprint — injecting natural perplexity variance, restoring burstiness, and transforming token distributions that Turnitin's classifier scans for.
This is not paraphrasing. It's structural rewriting at the statistical level. The result preserves your argument and evidence while producing text that is 100% undetectable by Turnitin and every other AI detector.
Step 3: Verify With the Real Turnitin Engine
Run your final text through the built-in Turnitin Checker — the same engine your professor uses. Not a clone, not an approximation. You see the exact AI detection score and per-sentence highlighting your professor will see.
If the report shows 0% AI detected, you're clear to submit. If any sentences flag (rare but possible on highly technical content), re-humanize those sections and re-check. You never submit blind.
Plans and Pricing
Every plan starts at $1.45/week. If you regularly use GrammarlyGO or heavy rewriting features, the Study Pass at $4.50/week bundles the humanizer with real Turnitin checks — the complete generate-humanize-verify workflow.
| Feature | Basic Free | Turnitin Pass $1.45/wk | Turnitin+ Pass $2.49/wk | Study Pass $4.50/wk | Study Pass+ $9.95/wk |
|---|---|---|---|---|---|
| Humanizer Words | 500 lifetime | — | — | 50,000/week | 250,000/week |
| Real Turnitin Checks | — | 2/week | 5/week | 3/week | 10/week |
| AI Detection Report | Included | Included | Included | Included | Included |
| Homework Unlocks | — | — | — | Included | Included |
Recommended for GrammarlyGO users: the Study Pass at $4.50/week. You get 50,000 humanizer words plus 3 real Turnitin checks per week — enough to humanize GrammarlyGO output and verify it before every submission. If you only need Turnitin checks without humanization (because you stick to safe Grammarly features), the Turnitin Pass starts at $1.45/week.
Every paid plan bills weekly with no contracts. Compare all options on the pricing page.