All Caps Text: Readability, Accessibility and When It Works

Why all caps feels like shouting

On the internet, a message written in capital letters is read as shouting. The convention dates back to the early days of email and discussion boards, when plain text offered no bold or italics and capitals were the only way to show emphasis. Over time it became a rule of netiquette: capitals for a single word to stress it, and never for a whole message.

The effect on the reader is real, even when the writer does not mean to be aggressive. A sentence such as "PLEASE SEND THE REPORT TODAY" reads as more urgent and less polite than "Please send the report today". Customer support teams and writing guides therefore advise against all capitals in emails, chat messages and social media posts, unless the text is a short label or an agreed code.

The readability problem

Lowercase words have more varied outlines, with letters that rise above the line, such as b, d and l, and letters that drop below it, such as g, p and y. In capitals, every letter is the same height, so every word forms a rectangle. Reading researchers have long reported that long stretches of capitals are read more slowly than the same text in lowercase, and that readers make more errors.

The effect is small for a short label and large for a paragraph. A warning sign with two words in capitals is fine. A page of terms and conditions in capitals tires the eye and is often skipped. That is one reason why accessibility guidance for plain language recommends sentence case for body text and keeping capitals for rare, short uses.

Accessibility and screen readers

For readers with dyslexia or low vision, uniform letter shapes make recognition harder, and the extra width of capital letters makes lines longer. Many guidelines on accessible text, including those by organizations that support readers with dyslexia, advise against long passages in capitals.

Screen readers add another consideration. Some screen readers, in some settings, read a word in capitals letter by letter if they take it for an abbreviation, which turns a headline into a string of letters. Behavior varies between products and settings. A safer approach is to write the text in normal case and use the CSS property text-transform: uppercase for the visual effect. The underlying text stays in normal case, so assistive technology reads it normally.

When capitals work well

Capitals are useful in short, deliberate places. Single words for emphasis, such as "NOT" in an instruction, abbreviations such as NASA, PDF and USA, and labels on buttons, signs and packaging are all fine. Warnings often use capitals for the signal word, as in NOTE, WARNING and DANGER. Legal documents sometimes use capitals for limitations of liability and disclaimers to make them conspicuous, because some jurisdictions expect certain clauses to be easy to notice.

Design is another area. Headings in small capitals, logos and posters can use capitals for style, with extra letter spacing to improve legibility. Typographers recommend adding a little space between capital letters, because capitals set at normal spacing look cramped.

Alternatives to capitals for emphasis

If you need emphasis in plain text, there are better choices than capitals. Bold type draws attention to a phrase without the harsh tone. Italics give a lighter stress. A short heading, a list or a line of space around important text also works. In a message that does not support formatting, asterisks around a word, as in *this*, are a widely understood stand-in for bold or italics.

In interface text, a clear verb in sentence case is usually better than capitals: "Delete account" is easier to scan than "DELETE ACCOUNT" and sounds less alarming. Reserve capitals for the rare cases in which you really want the reader to stop.

Switching all-caps text to lowercase or sentence case

If you have received or copied a paragraph in capitals, you can fix it in seconds. Paste it into the converter and click lowercase if you want everything in small letters. Click Sentence case if you want normal sentences: the converter lowercases the text and then capitalizes the first letter of each sentence.

After conversion, read through the result once. Names, acronyms and the pronoun I are lowercased by the conversion, and you must restore them by hand. The converter does capitalize the English pronoun I when it stands alone, but it cannot know that nasa should be NASA or that paris should be Paris.

A short style rule you can use

Use capitals for single words that need a strong stress, for established abbreviations, and for short labels. Do not use them for headings in running text, for whole sentences, for emails or for any text that someone has to read for more than a few seconds. When you must have capitals in the layout, use the CSS text-transform property, so the text itself stays in normal case.

These rules help readability, politeness and accessibility at the same time. And if you inherit a document written in capitals, convert it to sentence case, fix names and acronyms, and let the layout do the styling.