Capitalizing i and ı

Turkish has two different "i" letters — dotted i and dotless ı — and they are distinct letters with distinct sounds, not stylistic variants. English speakers usually learn this for lowercase. The trap is in the capitals, because the rule is the exact opposite of what an English keyboard does automatically. Get this one rule right and you will spell İstanbul, İzmir, and İngilizce correctly every time; get it wrong and you will quietly mangle proper nouns without noticing.

Two letters, two fixed case pairs

In English, "i" and "I" are the lowercase and uppercase of a single letter, and the dot just vanishes when you capitalize. Turkish keeps the dot as meaningful. There are four characters here, and they pair up like this:

So the capital of i is İ (with a dot on top), and the capital of ı is I (no dot). These two pairs never cross over: a dotted letter stays dotted in both cases, a dotless letter stays dotless in both cases. The "dottedness" is a property of the letter, and capitalization never changes it.

The word iş ("work, job") begins with dotted i, so capitalized it is İş — with the dot. The city İzmir likewise keeps its dot in capital form.

Why is this so easy to get wrong if the rule is just one line? Because English has trained a deep habit that runs in the opposite direction. In English the dot on lowercase "i" is purely decorative — a tittle with no meaning — and it always disappears in the capital "I." Your hands have typed that pattern thousands of times. Turkish, by contrast, treats the dot as a real distinguishing mark, the same way it treats the cedilla on ç or the breve on ğ: removing it produces a different letter that sounds different. So you are not learning a fiddly exception; you are unlearning the English assumption that dots are cosmetic. In Turkish, the dot is data.

Why English speakers get this wrong: autocorrect

The reason this is worth its own page is not that the rule is hard — it is one line — but that your keyboard fights you. Word processors and phones set to an English locale "know" that the capital of lowercase i is dotless I, because that is true in English. When you type a Turkish word, that autocorrect silently strips the dot off İ or adds a dot where there should be none. The error is invisible while you type and only shows up later in a name that now looks subtly foreign.

İngilizce ("English [language]") and İngiltere ("England") both start with dotted İ. On an English keyboard, autocorrect will routinely turn these into "Ingilizce" / "Ingiltere" with a dotless I — which is wrong. You must type the İ deliberately, with a Turkish keyboard layout or by inserting the character.

The most-mistyped word in the language is probably İstanbul: an English autocorrect renders it "Istanbul," dropping the dot. To a Turkish reader, the dotless capital signals the other vowel — the spelling looks off even when the word is recognizable.

Capitalizing dotless ı

The mirror case matters just as much, even though it appears in fewer everyday proper nouns. The capital of dotless ı is dotless I — and here English autocorrect makes the opposite mistake, sometimes adding a dot.

The word ısı ("heat, temperature") begins with dotless ı; written in all capitals it is ISI, with no dots. A common abbreviation, set in capitals, shows the rule cleanly:

ısıtma ("heating") capitalized is ISITMA — three dotless I's in a row. If your software produces "İSİTMA" with dots, it has wrongly applied the dotted pair.

The province Iğdır begins with dotless I in its correct spelling — a useful proper-noun example of the dotless capital, and exactly the kind of word an English keyboard will try to "fix" into a dotted İ.

The two pairs side by side

Here is everything on one screen, with a word that contains both letters to drive it home:

In ışık ("light") every "i"-type vowel is dotless, so the all-caps form IŞIK has no dots at all — the perfect counterpart to dotted İLGİNÇ.

Common mistakes

The lowercase is istanbul with dotted i, so the capital must be İ, not I.

When you capitalize ısı, the dots must not appear — it is ISI, not "İSİ."

Key takeaways

• Turkish has two i-letters: dotted i / İ and dotless ı / I. They are different letters, not just upper/lower forms of one.
• The capital of i keeps its dot: i → İ. The capital of ı has no dot: ı → I.
• Capitalization never adds or removes a dot — it only changes size. If the dot appears or vanishes, you switched letters.
• English-locale autocorrect silently breaks this, turning İstanbul into "Istanbul" and İngilizce into "Ingilizce." Type İ and ı deliberately, with a Turkish layout if possible.