Why Spelling Errors Aren't Being Caught on Mac

The most common reason spelling errors aren't caught on Mac is that the mistake creates a real word: typing "form" instead of "from", or "their" instead of "there". Standard dictionary-based autocorrect cannot catch these because both words are valid. Context-aware tools like Charm catch approximately 35% more of these errors by analysing the words surrounding the mistake to determine which word was intended.

Real-word substitutions: the errors no standard autocorrect catches

Autocorrect works by comparing what you type against a dictionary. If the word you typed exists in that dictionary, it passes - no correction, no flag, no warning. This approach works well for pure typos like "teh" or "recieve", where the result is not a real word. It breaks down entirely when your mistake happens to be a word.

Real-word substitutions are the category where this matters most. These are errors where a typo or slip produces a different valid word instead of nonsense. Common examples:

• from / form - "I am coming form home"
• their / there / they're - "Their going to the meeting"
• its / it's - "The company announced it's new product"
• your / you're - "Your going to love this"
• to / too / two - "I have to many tabs open"
• affect / effect - "The change had a major affect on results"

In every case above, the word that was typed is a perfectly valid English word. A dictionary lookup returns a hit. The autocorrect engine sees no error and moves on. The mistake reaches the recipient.

Real-word substitutions account for approximately 25% of all professional spelling errors - and they are the category most likely to slip through undetected. In professional writing, this is the kind of error that damages credibility precisely because it looks intentional.

Other reasons spelling errors slip through

Real-word substitution is the most common culprit, but there are several other reasons a spelling error might not get caught:

The app doesn't support macOS spell checking. Many popular applications are built on Electron - a cross-platform framework that doesn't integrate with macOS system services. Slack, VS Code, and Discord are all Electron apps. Spelling errors in these apps are not checked by the macOS spell check system at all, because the apps run their own isolated text engine. You may have autocorrect working perfectly elsewhere and still see errors slide through in these specific tools.

Autocorrect is disabled in System Settings. It's easy to accidentally turn off. Go to System Settings, then Keyboard, then Text Input, click Edit, and check that "Correct spelling automatically" is switched on. If it was turned off without you realising, this is your fix.

The word is in your personal dictionary. macOS lets you add words to a personal dictionary so they're never flagged. If you accidentally added a misspelling at some point - perhaps by clicking "Learn Spelling" on a word you typed incorrectly - that misspelling will now pass all checks silently. You can review and remove entries from your personal word list in the same Text Input settings panel.

Very fast typing. Autocorrect has a small processing window. Extremely fast typists occasionally outpace the correction engine's response time, particularly in apps that handle text in non-standard ways. This is less common than the other causes, but it does happen.

Technical terms and proper nouns. Jargon, brand names, product names, and people's names often look like misspellings to a general dictionary. If your work involves specialised vocabulary, you may see false flags - or conversely, you may have added so many custom words to avoid false flags that genuine errors now sneak through alongside them.

How Charm catches errors standard autocorrect misses

Charm uses a different approach to correction. Rather than checking each word in isolation against a dictionary, it uses an ML-based contextual model that reads the words around a potential error to judge whether the word is correct in that position.

Take the sentence "I am coming form home." A dictionary check on each word returns all valid - from, form, coming, home are all real words. Charm's model reads the full phrase and identifies that "form" in this position is statistically very unlikely to be the intended word. "From" fits the sentence structure, grammar, and meaning. The correction is made automatically.

This is why Charm catches approximately 35% more real-word substitution errors than dictionary-based systems. The improvement isn't from a bigger dictionary - it's from understanding context. The same approach handles their/there/they're, its/it's, your/you're, and the rest of the homophone class that trips up conventional autocorrect.

Charm also works across every Mac app, including Electron apps like Slack and VS Code where macOS spell checking doesn't reach. It runs system-wide using accessibility APIs, so the correction layer follows you into every text field on your machine.

Quick checks: is your spell check actually running?

Before assuming the issue is something subtle, confirm that spell check is functioning at all. The fastest test: open Apple Notes and type "teh". If autocorrect is active and working, it will change "teh" to "the" as you type or when you press space. If "teh" stays as typed, your spell check is off or broken.

If the test fails, check these settings in order:

1. Open System Settings, go to Keyboard, then Text Input, and click Edit
2. Confirm "Correct spelling automatically" is checked
3. Check your personal word list for any accidentally added misspellings
4. Restart any Electron apps (Slack, VS Code, Discord) - their spell check setting is separate from the system setting

If spell check is running correctly but you're still seeing real-word substitutions slip through, that is the expected limit of dictionary-based correction. A context-aware tool is the only way to close this gap reliably.

Frequently asked questions

Why does autocorrect miss some spelling errors?

Autocorrect misses errors when the mistake produces a valid dictionary word. If you type "form" when you meant "from", both words exist, so the system has no way to flag the error. Dictionary-based correction can only catch words that don't appear in its word list - it cannot judge whether a word is contextually correct.

What spelling errors can't autocorrect catch?

Standard autocorrect cannot catch real-word substitutions - errors where the misspelling is also a valid word. The most common examples are their/there/they're, its/it's, your/you're, to/too/two, from/form, and affect/effect. These account for approximately 25% of all professional spelling errors and require context-aware correction to catch reliably.

Does Charm catch errors macOS autocorrect misses?

Yes. Charm uses ML-based contextual correction that analyses the words surrounding a potential error, not just the word in isolation. It can identify "form" as a likely typo for "from" in context, and catches approximately 35% more real-word substitution errors than dictionary-based systems. It also works in Electron apps like Slack and VS Code where macOS spell check doesn't reach.

How do I check if spell check is working on my Mac?

Open Apple Notes and type "teh". If autocorrect is working, it will automatically change it to "the". If nothing happens, spell check is disabled or not functioning. To re-enable it, go to System Settings, then Keyboard, then Text Input, click Edit, and make sure "Correct spelling automatically" is checked.