How to Type # on a Mac UK Keyboard

Press Shift+3 on a British Mac keyboard and you get £ — sensible for prices, maddening for hashtags, Markdown headings, and code comments. The hash is still there: Option+3. One keystroke to learn, plus a couple of longer-term fixes if you type # a hundred times a day.

The keystroke

On the British keyboard layout, type # with Option+3. That's it — hold Option (Alt on some keycaps) and tap 3. It works in every app, from Terminal to Twitter, on macOS 13, 14, and 15.

The background: US layouts put # on Shift+3, but British layouts reserve that spot for the pound sterling sign — £ is, after all, the local currency symbol. The hash didn't vanish; it moved to the Option layer, joining the other hidden characters that key combination unlocks.

Why your muscle memory keeps missing

If you switch between UK and US machines — or between a British Mac and tutorials written by Americans — "Shift+3 for #" is baked into half the instructions on the internet. Three durable fixes, in increasing order of commitment:

• Just learn Option+3. It's a single combo, it never conflicts with anything, and after a week it's automatic. This is the right answer for most people.
• Add the US layout alongside British — System Settings → Keyboard → Input Sources → Edit… → + → English → U.S. Switch with Ctrl+Space when you sit down to code, switch back for email. You gain Shift+3 for # but lose the £ key while switched (it becomes Option+3 — the two symbols neatly trade places).
• ABC layout is effectively the US arrangement under a neutral name — some UK Macs already have it in the list, so try it before adding anything.

Programmers who live in # — Python comments, Markdown, CSS colors — often keep US as their coding layout permanently. Writers and spreadsheet users who need £ constantly stay British and learn the combo. Both are right.

If Option+3 gives you something else

Getting € or £ or nothing from Option+3? You're probably not on the layout you think you're on. Check the input menu in the menu bar — if it shows U.S. or ABC, then # is already on Shift+3 and Option+3 types £ instead (the two layouts mirror each other: the symbols simply swap keys). Enable the menu under Keyboard → Input Sources → Edit… → Show Input menu in menu bar if it's hidden; one glance answers the question forever. This also explains why # "randomly stopped working" for people who added a second layout and forgot: Ctrl+Space had quietly switched it.

Don't confuse # with its lookalikes

Unicode has cousins that look similar but break things: ♯ (the musical sharp), № (the numero sign), and the full-width ＃. Hashtags, shell scripts, and configuration files want the plain ASCII # (U+0023) that Option+3 produces — if a copied-from-the-web hash ever behaves strangely in code, a lookalike is usually the culprit. Retype it with the keyboard and the problem evaporates.

See where everything else went

The £/# swap is one of several UK-layout surprises — @ and " also trade places relative to US keyboards, and ~ hides elsewhere. Rather than memorizing lists, spend a minute with the built-in map: enable the input menu (Keyboard → Input Sources → Edit… → Show Input menu in menu bar), choose Show Keyboard Viewer, and hold Option then Option+Shift. Every hidden character on your actual layout lights up, and the mystery goes out of the keyboard for good. For symbols you use rarely, the Character Viewer (Ctrl+Cmd+Space) finds anything by name.