In this guide · 8 sections
- 01Grammarly vs ChatGPT: what each is for
- 02In-line editing vs drafting: how staff actually use them
- 03House style, brand terms and Singapore English
- 04Data handling: what happens to your text
- 05What it costs for a team of five
- 06Which should your business choose?
- 07Do it yourself or get help?
- 08Frequently asked questions
Short answer
Pick Grammarly for polished emails in Outlook, Gmail and Word with a shared style guide. Pick ChatGPT Business to draft, summarise and analyse. Grammarly Pro costs US$12 per member a month on annual billing (US$30 monthly); ChatGPT Business is US$20 a user on annual billing.
Grammarly vs ChatGPT: what each is for
Prices in US dollars, approximate, as of October 2026, from Grammarly's pricing help article and OpenAI's ChatGPT Business overview.
Grammarly Pro
Edits where you typeUS$12/member/mo yearly, US$30 monthly
- Works inside Outlook, Gmail, Word, Google Docs and browsers
- Tone, clarity and full-sentence rewrites
- Shared style guide, brand tones and snippets for teams
- Up to 149 seats on Pro
Best for: Teams that write many customer emails and want them consistent.
ChatGPT Business
Drafts and thinks with youUS$20/user/mo yearly, US$25 monthly
- Drafts emails, proposals and reports from notes
- Summarises long threads and documents
- Shared projects with team instructions
- Not used for training by default
Best for: Teams that produce new documents and analysis.
Grammarly says it is now part of Superhuman, a suite that includes Grammarly, Coda and Superhuman Mail, and that Grammarly Pro replaces the old Grammarly Business plan. Enterprise is sold through Superhuman Go.
In-line editing vs drafting: how staff actually use them
The biggest practical difference is where the work happens.
| Task | Grammarly | ChatGPT |
|---|---|---|
| Fix typos and grammar in an email you are writing | Suggestions as you type, in the email itself | Copy, paste, ask, paste back |
| Make a reply sound calmer or more formal | Tone suggestions and one-click rewrites | Good, but you move text between windows |
| Draft a proposal from bullet points | Limited (AI prompts: 2,000 per member a month on Pro) | Strong; its main strength |
| Summarise a 40-email thread | Not its focus | Strong, especially with email connectors |
| Keep company terms spelled the same | Style guide and brand tones flag it automatically | Only if instructions are in the prompt or project |
For staff who mainly answer customers, Grammarly removes the most errors with the least effort, because it works in place. For staff who write longer documents, ChatGPT saves more time. Many teams use both. For more on ChatGPT's writing compared with Claude, see Claude vs ChatGPT for business writing. For AI built into your email client, see AI email assistants for Gmail and Outlook.
House style, brand terms and Singapore English
Consistency is where Grammarly is ahead. Its Pro plan includes a style guide, brand tones and snippets for the team, so a product name, a refund phrase or a sign-off is suggested the same way for everyone.
Grammarly supports five English dialects: American, British, Canadian, Australian and Indian. There is no Singapore English option. Singapore business writing generally follows British spelling, so set every account to British English and add local terms (street names, Singlish words used deliberately, product names) to the team style guide.
Write a one-page style guide
Spelling (British), date format (20 October 2026), currency (S$), how you sign off, words you never use.
Set British English for every user
In Grammarly, under Language settings. In ChatGPT, put it in the project or custom instructions.
Add brand and local terms
Product names, place names and terms like HDB, CPF or PayNow so neither tool flags them.
Give ChatGPT the same rules
Paste the style guide into a shared project's instructions so drafts start in your house style.
Data handling: what happens to your text
Both tools see everything staff write with them, including customer details. Check the settings before rolling out.
- Grammarly: its Product Improvement and Training control is on by default for individual accounts and for multi-user accounts bought directly on its website, until an admin turns it off at account.grammarly.com/admin/data_settings. It is off by default for Enterprise and for plans bought through Grammarly's sales team.
- ChatGPT Business: OpenAI's enterprise privacy page says business data is not used to train its models by default.
- Personal accounts: staff using free Grammarly or free ChatGPT for work are outside both companies' business terms. Decide which accounts are allowed.
Our ChatGPT at work policy guide has a template for what staff may and may not paste into any AI tool.
What it costs for a team of five
Approximate yearly cost before tax at list prices, October 2026.
- Grammarly Pro, 5 members, annualUS$144 per member per yearUS$720
- Grammarly Pro, 5 members, monthlyUS$30 per member per monthUS$1,800
- ChatGPT Business, 5 users, annualUS$20 per user per monthUS$1,200
Both, on annual billingabout US$1,920 a year
Prices from vendor pages as of October 2026. Overseas digital services may attract 9% GST.
Grammarly's monthly price is two and a half times its annual average, so only pay monthly for a short trial.
Which should your business choose?
Choose Grammarly if
- Most writing is short customer emails
- You want one house style enforced for everyone
- Staff should not have to switch windows
- Budget is tight; annual Pro is cheaper
Choose ChatGPT if
- Staff draft proposals, reports and policies
- You need summaries of long threads and documents
- You want an assistant for analysis too
- You already use ChatGPT Business for other work
If you only buy one, buy the one that matches the writing your staff do most. You can always add the other for the two or three people who need it.
Do it yourself or get help?
Rolling out either tool is mostly settings: dialect, style guide, training controls and which accounts staff may use. A manager can do it in an afternoon using the steps above.
If you want staff trained on safe AI use, what never to paste into a writing tool, and how to spot AI-written phishing, our Security Awareness Training session (S$390, paid upfront) covers it. IT Sorted is a Singapore-based team of developers with over 10 years of experience.
Frequently asked questions
Grammarly's help centre lists Pro at US$30 per member per month on a monthly plan, US$60 per member per quarter, or US$144 per member per year, which averages US$12 a month. Pro plans allow up to 149 seats. Larger organisations buy Enterprise through sales. Prices are as of October 2026.
It can, depending on how you bought it. Grammarly says Product Improvement and Training is on by default for individual accounts and for multi-user accounts bought on its website, and an admin can turn it off for the whole organisation. It is off by default for Enterprise and plans purchased through Grammarly's sales team.
Not as a separate option. Grammarly offers American, British, Canadian, Australian and Indian English. Most Singapore businesses use British spelling, so British English is the closest setting. Add local terms and brand names to the team style guide so they are not flagged as errors.
For drafting and rewriting, yes, but it works in a separate window unless you use an integration. Grammarly checks text as staff type in Outlook, Gmail, Word and browsers, and enforces a shared style guide. Teams that mostly answer customer emails often find Grammarly faster; teams that write long documents get more from ChatGPT.
On ChatGPT Business, OpenAI says business data is not used for training by default, and the account belongs to the company. Still, only share what is needed: remove NRIC numbers, payment details and anything unnecessary. Free personal ChatGPT accounts should not be used for customer data. Set a short written rule for staff.