How to Train Your Mac to Learn Your Writing Style

You train your Mac to your writing style primarily through two methods: building a personal dictionary for words macOS does not recognise, and using Charm, which learns your vocabulary and writing patterns automatically over time. The combination means fewer false corrections and better word predictions tailored to how you actually write - without any manual training sessions.

Building your personal dictionary on Mac

macOS ships with a built-in spell checker that applies the same dictionary to every writer on every Mac. A lawyer, a developer, and a novelist all start with identical correction rules. That is the root cause of most false positives: the system simply does not know your vocabulary.

The personal dictionary is how you fix this. When macOS or Charm flags a word incorrectly, right-click it and select Learn Spelling. The word is permanently added to your personal dictionary and will never be flagged again across any app on your Mac. There is also an Ignore Spelling option, which dismisses the correction for that session only - useful when you want to skip without making a permanent change.

You can also manage Text Replacements directly in System Settings. Go to System Settings > Keyboard > Text Replacements. Here you can add phrases, abbreviations, or terms that should always be treated as correct. If you have iCloud enabled, your personal dictionary syncs across all your Apple devices automatically.

Good candidates for the personal dictionary include:

• Proper nouns: your name, client names, brand names, company names
• Technical terms specific to your field: medical terminology, programming keywords, legal Latin
• Intentional stylistic choices: abbreviations or short forms you always use
• Domain slang: industry-specific words that standard dictionaries do not carry

The key distinction: Learn Spelling tells macOS this word is correct everywhere, permanently. Ignore Spelling dismisses it just this once. For any word you write regularly, Learn Spelling is the right choice.

How Charm learns your writing style automatically

macOS's personal dictionary requires you to actively add words. Charm goes further: it watches how you write and adapts without any manual input.

Charm uses an on-device machine learning model that observes your writing patterns across every app where you type. It tracks which word combinations you use frequently, which corrections you accept or reject, and how your sentence structures tend to flow. None of this data leaves your Mac - all learning happens locally, using your device's own processing.

Two features benefit most from this learning. Spells, Charm's correction engine, becomes progressively less likely to flag words and constructions you use consistently. If you write "async/await" fifty times a day, Charm stops treating it as a potential error. Oracle, Charm's word prediction feature, becomes more accurate at anticipating your next word as it builds a model of your specific vocabulary and phrasing patterns.

The improvement is measurable. After two weeks of regular use, Oracle prediction accuracy improves by approximately 30% compared to a fresh install. Most users notice a meaningful difference within just a few days - the suggestions start feeling specific to how they write, not generic.

No configuration is required. Install Charm, use it normally, and the adaptation happens in the background.

Text Replacements as style anchors

Text Replacements serve a different purpose from the personal dictionary. Instead of teaching macOS that a word is correct, Text Replacements lock in a specific phrase so it always expands consistently.

Think of it as a style anchor: phrases you always write exactly the same way, every time. Common examples include sign-off phrases ("Kind regards,"), standard disclaimers, addresses, recurring technical boilerplate, or long proper nouns you always abbreviate the same way when typing quickly.

To add one, go to System Settings > Keyboard > Text Replacements and click the plus button. Type the short trigger in the Replace column and the full phrase in the With column. The replacement fires in any text field, system-wide, as soon as you type the trigger and press space.

Used well, Text Replacements eliminate a whole category of variation errors - those moments where you spell a company name two different ways in the same document, or where your sign-off drifts between sessions. They are particularly useful for writers who produce high volumes of similar content and need consistency without effort.

What good personalisation looks like

The goal of personalising your Mac's writing tools is simple: zero false corrections. Every red underline that does not belong is friction, and friction compounds across thousands of keystrokes per day.

Different writers have different vocabularies that standard tools fail:

A software developer writes "async/await", "useState", "webpack", "typeof", and hundreds of other terms that a standard dictionary treats as errors. Without a personal dictionary and an adaptive tool like Charm, every code comment or technical document becomes a false-positive minefield.

A doctor or clinician writes "tachycardia", "myocardial", "contraindicated", "subcutaneous" as everyday vocabulary. Generic autocorrect mangles or flags these constantly. A personal dictionary tuned to medical terminology eliminates the interruptions.

A novelist or literary writer uses intentional fragments, unconventional punctuation, and dialect. A good personalisation setup means those choices are preserved, not overridden. Charm's learning model recognises that these patterns are intentional, not mistakes.

A non-native English speaker may have perfectly correct, idiomatic usage that differs from the dominant dialect in macOS's dictionary. Their personal dictionary and Charm's adaptive model together mean the tool corrects actual errors rather than dialect differences.

A fully personalised setup feels invisible. The tool catches what you actually got wrong and leaves everything else alone.

Frequently asked questions

How does macOS learn my writing style?

macOS learns your writing style through two mechanisms: an explicit personal dictionary (words you add via right-click > Learn Spelling or System Settings > Keyboard > Text Replacements) and passive adaptation, where the system observes corrections you accept or ignore over time. There is no dedicated training mode - personalisation is gradual and largely automatic.

How long does it take Charm to adapt to my writing?

Charm begins adapting from your first session. Most users notice a meaningful improvement in Oracle prediction accuracy within a few days of regular use. After two weeks, Oracle accuracy improves by approximately 30% compared to a fresh install, as the model builds a detailed picture of your vocabulary and writing patterns.

Does Charm send my writing data to learn from?

No. Charm learns entirely on your device. All pattern recognition, vocabulary modelling, and prediction improvements happen locally using on-device machine learning. Your keystrokes never leave your Mac, and no writing data is transmitted to any server.

How do I teach Mac to stop correcting a specific word?

Right-click the word while it is underlined by autocorrect and select Learn Spelling. This adds the word to your macOS personal dictionary and prevents future corrections across all apps. For words you want to ignore only once without permanently adding them, choose Ignore Spelling instead.