Grammarly offers two primary service tiers—Free and Premium (now called Pro)—that cater to different writing needs, with the Premium version providing significantly expanded functionality. The free version serves as a basic writing assistant, focusing on core grammar, spelling, and punctuation corrections, while Premium unlocks over 400 advanced features designed for professional and academic writing. Key differentiators include plagiarism detection, genre-specific writing suggestions, full-sentence rewrites, and AI-powered tone adjustments. Premium also introduces collaboration tools for teams and integrates with more applications, making it a comprehensive solution for businesses and serious writers.

• Core Free Features: Spelling, grammar, and punctuation checks, plus basic tone detection and conciseness suggestions ^[2][4]
• Premium Exclusives: Plagiarism detection, 2,000 monthly AI prompts (vs. 100 in Free), fluency suggestions, and formatting assistance ^[3][7]
• Pricing Structure: Free version is no-cost; Premium starts at $12/month (annual billing) with a 25% discount available until September 2025 ^[3][8]
• Target Users: Free suits casual users; Premium targets professionals, students, and teams requiring advanced writing analytics ^[6][9]

Grammarly Free vs. Premium: Feature Breakdown and Use Cases

Core Writing Assistance and Accuracy

The free version of Grammarly functions as a foundational writing tool, addressing surface-level errors that impact clarity. It identifies misspelled words, grammatical mistakes, and punctuation inconsistencies in real time, making it accessible for users who need quick corrections without advanced analysis. The tone detector in the free version provides basic feedback on whether writing sounds formal, friendly, or neutral, though it lacks the nuanced adjustments available in Premium ^[2]. For example, a student drafting an essay would receive alerts about subject-verb agreement errors or missing commas, but wouldn’t get suggestions for improving sentence variety or academic tone ^[6].

Premium elevates this functionality with context-aware suggestions that adapt to specific writing goals. Key advancements include:

• Genre-Specific Writing Styles: Premium analyzes the intended audience (e.g., business, academic, creative) and tailors suggestions accordingly, such as recommending concise phrasing for professional emails or more descriptive language for fiction ^[3]
• Fluency and Readability Enhancements: The tool flags awkward phrasing, wordiness, and passive voice, offering rewrites that improve flow. For instance, it might suggest changing "due to the fact that" to "because" for conciseness ^[4]
• Vocabulary Expansion: Premium proposes synonyms and more precise word choices to strengthen impact, such as replacing "very important" with "critical" in a business report ^[1]
• Advanced Tone Adjustments: Beyond detecting tone, Premium allows users to set a desired tone (e.g., "confident," "empathetic") and receive suggestions to align the text with that tone ^[7]

A direct comparison of error detection shows Premium catches 40% more issues than the free version, particularly in complex sentences and nuanced grammar rules like misplaced modifiers or parallel structure errors ^[10]. However, users note that neither version replaces manual proofreading for highly technical or creative content, where context-specific judgment is required ^[10].

Plagiarism Detection and Professional Tools

One of the most significant Premium exclusives is the plagiarism detector, which scans text against 16 billion web pages and academic databases to identify unoriginal content. This feature is critical for students, researchers, and content creators who must ensure originality. The tool highlights matching text and provides source links, though it doesn’t evaluate whether the usage constitutes fair use or proper citation ^[1]. For example, a university student submitting a paper would receive alerts if phrases match published works, along with guidance on paraphrasing or adding citations ^[6].

Premium also introduces tools designed for professional workflows:

• Citation Suggestions: The system recommends APA, MLA, or Chicago-style citations when it detects uncited sources, reducing manual formatting time ^[4]
• Full-Sentence Rewrites: Users can select a sentence and generate multiple alternative versions with one click, which is particularly useful for overcoming writer’s block or refining messaging ^[5]
• Team Collaboration Features: Grammarly Pro (the team-oriented Premium tier) includes shared style guides, brand tone consistency tools, and analytics dashboards to track team writing performance. For instance, a marketing team can enforce a unified brand voice across all content ^[5][8]
• AI-Powered Prompts: Premium users receive 2,000 monthly AI-generated writing prompts (compared to 100 in Free), which help brainstorm ideas or structure outlines for projects ^[7]

The plagiarism checker’s accuracy is noted as high, though some users report occasional false positives with common phrases or technical terms ^[10]. For businesses, the collaboration tools integrate with platforms like Google Docs, Microsoft Word, and Slack, enabling real-time feedback without switching applications ^[5]. This seamless integration is a key advantage over the free version, which lacks team functionalities and third-party app support beyond basic browsers ^[8].