Ben was about to send his proposal to a potential client, a company he'd been trying to win for months. The email was polished. The offer was strong. The first line read: "Thank you for your concideration."
He caught it by chance, just before pressing send. If he hadn't, would the client have noticed? Maybe not. But maybe so, and maybe it would have planted a small thought: if he's careless here, how careful will he be with our project?
Spelling and grammar mistakes feel minor, but readers use them as quick signals of attention and credibility. The good news is that today you can catch most of them automatically.
- Mistakes can make businesses look careless, especially in first contact with a customer.
- One UK entrepreneur reported in 2011 that fixing a single spelling error on his website doubled revenue per customer. It's an anecdote, not a controlled study, but it shows the stakes.
- Grammar AI tools check spelling, grammar, punctuation and clarity as you write.
- These tools miss things, and they can flatten your personal voice if you accept every suggestion.
- Be careful with confidential information. Check what each tool does with your text.
What a Typo Really Costs
In 2011, Silicon Republic reported on Charles Duncombe, an entrepreneur who ran several websites. He said a spelling mistake could reduce sales because visitors saw the business as less trustworthy, and in one case he reported that fixing a single error doubled revenue per customer.
It's important to read that fairly: it's one person's account, not a rigorous experiment, and your results will differ. But the underlying idea is sensible. Readers can't inspect your product from an email or website, so they judge the small details they can see.
The cost isn't only lost sales. A typo in a proposal, a contract, a customer apology or a job application can quietly weaken the message you were trying to send.
How Grammar AI Works
Older spell checkers only compared your words with a dictionary. That's why "their" and "there" pass without a flag. Modern grammar tools look at the whole sentence, using language models to spot problems such as:
- Misspelled words and wrong word choices ("affect" vs "effect")
- Grammar errors, missing words and punctuation problems
- Long, confusing sentences
- Tone issues, such as sounding harsher than you intended
Most work as browser extensions, desktop apps or built-in features, so you get suggestions as you type in email, documents and social media.
Tools Worth Trying
Options and prices change often, so check each tool's current plan and limits before relying on it. Here are common choices:
Grammarly
One of the best-known writing assistants, founded in 2009. It has used a free-to-start model since 2015, with extra style and advanced features in paid plans. Its parent company announced a rebrand to Superhuman in October 2025, but the writing assistant is still known as Grammarly.
LanguageTool
A grammar and spelling checker that supports many languages, which helps if you write in more than one. It offers a free version with limits.
Microsoft Editor
Built into Microsoft 365 apps such as Word and Outlook, so it's convenient if you already use them.
Built-in checks in Gmail and Google Docs
Free, simple and already there. They catch many basic errors, which may be enough if you write short emails.
A general AI assistant
You can paste text and ask it to "fix spelling and grammar only, don't change my wording." It's flexible, but clear instructions matter.
A 60-Second Check for Every Email
The best system is simple enough that you'll actually use it:
- Write first, edit second. Don't check as you type. Get your thoughts down, then fix them.
- Run the grammar tool. Review each suggestion. Don't accept them blindly.
- Check names and numbers yourself. Tools often miss wrong names, wrong dates and wrong prices, and these mistakes hurt most.
- Read the first and last lines aloud. They matter most, and reading aloud exposes awkward phrasing.
- Check the subject line and any links. A typo in a subject line is the first thing the reader sees.
- Pause on important emails. For proposals, apologies and contracts, wait a few minutes or ask a colleague to read it.
Where Grammar AI Gets It Wrong
Names, brands and technical terms
Tools may flag or change unusual names. Add your brand and product names to the custom dictionary so they're handled correctly.
Correct words used wrongly
If you type a real word that doesn't fit your meaning, a tool may not catch it. This is why a final human read matters.
Confident but wrong suggestions
AI can suggest a change that sounds better but breaks your meaning. Review every change.
Different English
Spelling and style differ between American and British English. Set your language variant so you don't get mixed results.
Privacy: What You Paste Matters
Many grammar tools process your text on their servers. Before you use one for sensitive material, check its privacy policy and settings:
- Does it store your text, and for how long?
- Is your text used to train its models, and can you opt out?
- Does your company have rules about using such tools with client data?
When in doubt, don't paste confidential information such as contracts, personal data or financial details into any online tool. The same careful habits apply to protecting your accounts, as we describe in cybersecurity basics.
Don't Let It Erase Your Voice
Fixing errors is one thing. Rewriting everything is another. If you accept every "improvement," your emails can start sounding generic. Keep the personality that makes you recognizable, and use the tool as a proofreader, not a ghostwriter.
This is closely related to the idea in using AI as a partner, not a copy machine. And if you want your writing to sound consistent everywhere, see our guide to brand voice consistency.
Conclusion: Make Every First Impression Clean
Ben now runs every important email through a grammar tool and reads the first line aloud. That "concideration" mistake never reached a client again. He also adds his company and product names to his custom dictionary so the tool stops arguing with him.
This week, install one free grammar tool and set up your custom dictionary. Then try the 60-second check on your next three emails. You can't make every message perfect, but you can stop the easy mistakes from reaching your reader.
Frequently Asked Questions
Can grammar AI really prevent all typos?
No. It catches many spelling, grammar and punctuation errors, but it can miss wrong names, wrong numbers and real words used incorrectly. A final human read is still important.
Are there free grammar checkers?
Yes. Many tools, including Grammarly and LanguageTool, offer free versions with limits, and Gmail, Google Docs and Microsoft Editor have built-in checks. Plans change, so check current features.
Do typos really hurt sales?
They can reduce trust, especially in first contact. One entrepreneur reported doubling revenue per customer after fixing a single error, but that was an anecdote. The safest assumption is that careful writing signals care.
Is it safe to paste confidential text into a grammar tool?
Check the tool's privacy policy and settings first. Avoid pasting contracts, personal data or financial details unless you're sure how the text is stored and used.
Will grammar AI change my writing style?
It can if you accept every suggestion. Use it to fix errors, and keep wording that sounds like you.
