How to turn on Caps Lock on the iPhone keyboard
The shift key has three states, not two, and the difference between them is the whole trick. Here is what each one means, the double-tap gesture that locks capitals on, and the Settings switch that turns the gesture off entirely.
Everyone who has typed on an iPhone has hit the arrow key in the bottom-left corner of the keyboard by accident and watched one letter come out capitalized when they did not mean it to. Far fewer people know the same key can lock the whole keyboard into capitals on purpose, because the gesture that does it is a double-tap rather than anything the keyboard spells out on screen — and if you have ever tried it and had nothing happen, there is a specific, ordinary reason for that too.
The shift key has three states
That arrow icon is not just on or off. It carries three separate meanings, and the confusion around Caps Lock almost always comes down to not knowing which one you are looking at.
- Outline arrow, resting — the next letter you type will be lowercase. This is where the key sits by default, mid-sentence, once whatever capitalized the last letter has worn off.
- Solid arrow, briefly highlighted — Shift is armed for exactly one letter. Tap it once, or let Auto-Capitalization arm it for you at the start of a sentence, and the very next letter comes out capitalized before the key drops back to resting on its own.
- Solid arrow with the whole key visibly locked on — Caps Lock. Every letter comes out capitalized until you tap the key again to release it, no matter how long that takes or how many words you type in between.
Turning it on: double-tap the shift key
- Bring up the keyboard in any text field.
- Tap the shift key — the arrow, bottom-left of the letter keys — twice in quick succession, the same motion as double-tapping an app icon.
- Watch the key: it should visibly light up or box itself in, rather than just flashing solid for a moment the way a single tap does.
- Type. Every letter comes out capitalized, sentence after sentence, until you touch the key again.
- Tap it once more to drop back to ordinary lowercase typing.
The gesture only works if the two taps land close enough together to register as one double-tap rather than two separate single ones — the same timing iOS expects for double-tapping anything else on screen. A slow tap, tap ends up arming Shift for one letter, releasing it, then arming it again for the next, which types two capital letters rather than locking anything.
If double-tapping does nothing at all
When two clean, fast taps produce no lock whatsoever — not even a flicker of the key trying to highlight — the gesture itself has been switched off. Go to Settings → General → Keyboard and look for Enable Caps Lock. It is on by default; if it has been turned off, at some point by you, by someone else, or by a restored backup carrying an old preference, double-tapping Shift behaves as two ordinary single taps and nothing locks. Turn the switch back on and the gesture returns immediately, with nothing else to reset.
Caps Lock is not the same switch as Auto-Capitalization
The same Settings → General → Keyboard screen carries a separate Auto-Capitalization switch, and it is easy to assume the two are connected because they sit one above the other. They are not. Auto-Capitalization is what capitalizes the first letter of a new sentence for you as you type; Caps Lock is the double-tap gesture that locks every letter capital on purpose. Turning one off leaves the other exactly as it was — switch off Auto-Capitalization and you can still double-tap Shift to write a whole line in capitals, and switch off Enable Caps Lock and sentences still start with a capital letter the way they always did.
Why a third-party keyboard might not have it at all
A keyboard extension draws its own shift key and decides for itself how a single tap and a double-tap behave — the same way it decides on the space-bar trackpad gesture or the press-and-hold shortcut on the 123 key. iOS does not hand the double-tap-to-lock behavior to every keyboard automatically just because Apple’s own keyboard has it; a developer has to build the same gesture on purpose. So a keyboard that never locks into capitals no matter how you tap its shift key is not necessarily broken or missing a setting — it may simply be a keyboard that was never built to do this, the same as one that never grew a cursor trackpad.
Where Kibo fits
Kibo handles capitalization with its own logic rather than reading Apple’s Auto-Capitalization switch, consistent across whichever of its 30 typing languages you have enabled, and it still respects the per-field hint an app sends for a password or username box — the same behavior covered in the guide on turning off auto-capitalize. None of it needs Full Access, which Kibo reads only for the Copy word, Copy line and Paste buttons on its own toolbar. It is free to download.
Frequently asked questions
Why does double-tapping Shift not lock my iPhone keyboard into capitals?
Two likely causes. Either the two taps are landing too far apart to register as a double-tap, which arms and releases single capitals instead of locking anything, or Enable Caps Lock has been turned off in Settings → General → Keyboard, which disables the gesture entirely.
What does it mean when the shift arrow turns solid but does not stay locked?
That is a single armed shift, not Caps Lock. One tap capitalizes the next letter only, and the key drops back to its resting state as soon as that letter is typed. Caps Lock needs the double-tap and shows the whole key visibly locked on, not just the arrow flashing solid.
Does turning off Auto-Capitalization also turn off Caps Lock?
No. They are separate switches on the same Settings → General → Keyboard screen. Auto-Capitalization controls the automatic capital at the start of a sentence; Caps Lock is the double-tap-Shift gesture, and turning one off leaves the other untouched.
Does every third-party keyboard support double-tap Caps Lock?
Not necessarily. A keyboard extension draws its own shift key and has to build the double-tap-to-lock gesture on purpose — iOS does not provide it automatically the way it does for Apple’s own keyboard. Some third-party keyboards include it and some do not.
Try it on your own keyboard
Kibo is a free custom keyboard for iPhone with real mechanical key sounds, a wardrobe of themes and RGB backlight effects. No account, no ads, and it works with Full Access left off.