Head-to-head

Grammarly Pro vs ChatGPT Business vs Microsoft 365 Copilot

Grammarly Pro

8.6 $12

ChatGPT Business

9.5 $20

Microsoft 365 Copilot

9.1 $30

Verdict

Grammarly Pro

The most focused tool for writing quality: grammar, tone, and rewrites that work everywhere you type, plus team style guides, at $12/user/mo annual. Narrower than a full AI assistant, the prompt cap has no top-up, and auto-renewal billing catches people out.

ChatGPT Business

The most flexible single AI subscription: GPT-5.5 plus Deep Research, Custom GPTs, Canvas, and the Codex coding agent in one team workspace with strong admin controls. The two-seat minimum and per-seat feature limits aside, it does the most for the money.

Microsoft 365 Copi

The default AI layer for Microsoft-heavy teams: unmatched inside Word, Excel, Outlook, and Teams, and grounded in your own data through Graph. Just budget for the base license it rides on (real cost runs 2-3x the add-on price), and don't expect it to reach non-Microsoft tools.

Best for

Grammarly Pro

Students, professionals, sales teams, support teams, and anyone who writes often and wants clearer grammar, tone, rewriting, and everyday polish.

ChatGPT Business

Small businesses, solo operators, students, creators, and teams that want one flexible AI assistant for writing, research, planning, analysis, brainstorming, and everyday productivity.

Microsoft 365 Copi

Teams already standardized on Microsoft 365 who want AI built directly into the apps they live in — drafting and triaging email in Outlook, recapping meetings and surfacing action items in Teams, generating and rewriting documents in Word, building slides in PowerPoint, and getting formula and analysis help in Excel — without copying work into a separate chatbot.

Avoid if

Grammarly Pro

you need a full general-purpose AI assistant for research, reasoning, strategy, data analysis, or creative production.

ChatGPT Business

your main need is AI embedded directly inside Microsoft 365 or Google Workspace, or you only need a narrow specialist tool for design, grammar, or source-backed research.

Microsoft 365 Copi

Your organization isn't on a qualifying Microsoft 365 business plan, your team mostly works in Google Workspace or standalone tools, or you primarily want a general-purpose chat assistant for research and writing rather than AI embedded inside the Office apps.

Score breakdown

fit

Grammarly

8.6

ChatGPT Bu

9.6

Microsoft

9.2

ease

Grammarly

9.2

ChatGPT Bu

9.2

Microsoft

9.2

value

Grammarly

8.4

ChatGPT Bu

9.0

Microsoft

8.6

quality

Grammarly

8.5

ChatGPT Bu

9.5

Microsoft

8.9

Specs

Price

$12/user/mo annual ($144/yr); $30/mo monthly; $60/quarter (~$20/mo)

$25/user/mo monthly, $20/user/mo annual (2-seat minimum)

—

Seats

1–149 seats on Pro (replaces the old Premium and Business plans); 150+ goes to Enterprise

—

Security

SOC 2 Type 2; SSO/SCIM/DLP/BYOK and HIPAA BAAs are Enterprise-only

—

Works in

Browser extension, desktop app, mobile keyboard; integrates with Google Docs, Microsoft Word, and email

—

AI prompts

2,000 AI prompts/member/month (Free gets 100; Enterprise is unlimited)

—

Pro extras

Plagiarism detection, AI text detection, vocabulary and formatting suggestions, generative AI

—

Core writing

Grammar, spelling, clarity, conciseness, tone suggestions, and full-sentence rewrites

—

Team features

Style guide, brand tones, snippets, and team analytics

—

Enterprise step-up

Unlimited AI prompts, advanced security and admin, via Grammarly and Superhuman Go

—

API

—

Not included — billed separately

—

Trial

—

14-day onboarding trial

—

Models

—

GPT-5.5 and GPT-5.5 Pro, plus reasoning/Thinking models

OpenAI (GPT) models, with Anthropic Claude now also selectable

Compliance

—

SOC 2 Type 2, ISO 27001; no training on workspace data by default

—

Seat types

—

Standard ChatGPT seat, or usage-based Codex-only seat

—

Included tools

—

ChatGPT + Codex, Custom GPTs, Projects, Canvas, Deep Research, ChatGPT Agent, image generation

—

Admin & security

—

Shared workspace, admin console, SAML SSO, SCIM, MFA

—

Knowledge connectors

—

Google Drive, SharePoint, GitHub, and company knowledge

—

Advanced-feature limits

—

Per-seat limits on Deep Research, image gen, voice, and Codex; workspace credits cover overage

—

Apps

—

Word, Excel, PowerPoint, Outlook, and Teams, plus Copilot Chat on the web

Free tier

—

Copilot Chat — web-grounded chat included with eligible M365 plans; no access to org files, email, or Teams

Add-on model

—

An add-on to Microsoft 365 — cannot be bought standalone; requires a qualifying base plan

Custom agents

—

Copilot Studio for internal agents (capacity-based; Azure subscription required to run agents)

Data grounding

—

Your organization's data via Microsoft Graph; respects each user's existing permissions

Enterprise price

—

$30/user/mo, annual commitment

True all-in cost

—

~$30–43/user/mo on the Business lane to ~$66–87 on the Enterprise lane, including the base license

Base license required

—

Business Standard/Premium (Business tier) or E3/E5 (Enterprise tier)

Security & compliance

—

SOC 2, ISO 27001, GDPR, and HIPAA support at the Enterprise tier

Business price (≤300 users)

—

$18/user/mo promotional (standard $21), annual; ~$25.20 month-to-month

Buy →Buy →Buy →

	Grammarly Pro	ChatGPT Business	Microsoft 365 Copilot
Score	8.6	9.5	9.1
Price	$12	$20	$30
Verdict	The most focused tool for writing quality: grammar, tone, and rewrites that work everywhere you type, plus team style guides, at $12/user/mo annual. Narrower than a full AI assistant, the prompt cap has no top-up, and auto-renewal billing catches people out.	The most flexible single AI subscription: GPT-5.5 plus Deep Research, Custom GPTs, Canvas, and the Codex coding agent in one team workspace with strong admin controls. The two-seat minimum and per-seat feature limits aside, it does the most for the money.	The default AI layer for Microsoft-heavy teams: unmatched inside Word, Excel, Outlook, and Teams, and grounded in your own data through Graph. Just budget for the base license it rides on (real cost runs 2-3x the add-on price), and don't expect it to reach non-Microsoft tools.
Best for	Students, professionals, sales teams, support teams, and anyone who writes often and wants clearer grammar, tone, rewriting, and everyday polish.	Small businesses, solo operators, students, creators, and teams that want one flexible AI assistant for writing, research, planning, analysis, brainstorming, and everyday productivity.	Teams already standardized on Microsoft 365 who want AI built directly into the apps they live in — drafting and triaging email in Outlook, recapping meetings and surfacing action items in Teams, generating and rewriting documents in Word, building slides in PowerPoint, and getting formula and analysis help in Excel — without copying work into a separate chatbot.
Avoid if	you need a full general-purpose AI assistant for research, reasoning, strategy, data analysis, or creative production.	your main need is AI embedded directly inside Microsoft 365 or Google Workspace, or you only need a narrow specialist tool for design, grammar, or source-backed research.	Your organization isn't on a qualifying Microsoft 365 business plan, your team mostly works in Google Workspace or standalone tools, or you primarily want a general-purpose chat assistant for research and writing rather than AI embedded inside the Office apps.
Score breakdown
fit	8.6	9.6	9.2
ease	9.2	9.2	9.2
value	8.4	9.0	8.6
quality	8.5	9.5	8.9
Specs
Price	$12/user/mo annual ($144/yr); $30/mo monthly; $60/quarter (~$20/mo)	$25/user/mo monthly, $20/user/mo annual (2-seat minimum)	—
Seats	1–149 seats on Pro (replaces the old Premium and Business plans); 150+ goes to Enterprise	—	—
Security	SOC 2 Type 2; SSO/SCIM/DLP/BYOK and HIPAA BAAs are Enterprise-only	—	—
Works in	Browser extension, desktop app, mobile keyboard; integrates with Google Docs, Microsoft Word, and email	—	—
AI prompts	2,000 AI prompts/member/month (Free gets 100; Enterprise is unlimited)	—	—
Pro extras	Plagiarism detection, AI text detection, vocabulary and formatting suggestions, generative AI	—	—
Core writing	Grammar, spelling, clarity, conciseness, tone suggestions, and full-sentence rewrites	—	—
Team features	Style guide, brand tones, snippets, and team analytics	—	—
Enterprise step-up	Unlimited AI prompts, advanced security and admin, via Grammarly and Superhuman Go	—	—
API	—	Not included — billed separately	—
Trial	—	14-day onboarding trial	—
Models	—	GPT-5.5 and GPT-5.5 Pro, plus reasoning/Thinking models	OpenAI (GPT) models, with Anthropic Claude now also selectable
Compliance	—	SOC 2 Type 2, ISO 27001; no training on workspace data by default	—
Seat types	—	Standard ChatGPT seat, or usage-based Codex-only seat	—
Included tools	—	ChatGPT + Codex, Custom GPTs, Projects, Canvas, Deep Research, ChatGPT Agent, image generation	—
Admin & security	—	Shared workspace, admin console, SAML SSO, SCIM, MFA	—
Knowledge connectors	—	Google Drive, SharePoint, GitHub, and company knowledge	—
Advanced-feature limits	—	Per-seat limits on Deep Research, image gen, voice, and Codex; workspace credits cover overage	—
Apps	—	—	Word, Excel, PowerPoint, Outlook, and Teams, plus Copilot Chat on the web
Free tier	—	—	Copilot Chat — web-grounded chat included with eligible M365 plans; no access to org files, email, or Teams
Add-on model	—	—	An add-on to Microsoft 365 — cannot be bought standalone; requires a qualifying base plan
Custom agents	—	—	Copilot Studio for internal agents (capacity-based; Azure subscription required to run agents)
Data grounding	—	—	Your organization's data via Microsoft Graph; respects each user's existing permissions
Enterprise price	—	—	$30/user/mo, annual commitment
True all-in cost	—	—	~$30–43/user/mo on the Business lane to ~$66–87 on the Enterprise lane, including the base license
Base license required	—	—	Business Standard/Premium (Business tier) or E3/E5 (Enterprise tier)
Security & compliance	—	—	SOC 2, ISO 27001, GDPR, and HIPAA support at the Enterprise tier
Business price (≤300 users)	—	—	$18/user/mo promotional (standard $21), annual; ~$25.20 month-to-month
	Buy →	Buy →	Buy →

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