だ (plain copula)
da
By Nihongo PathUpdated
Meaning
Plain/casual equivalent of です.
だ is the plain (casual) version of です. Both mean "is / am / are". You use だ with close friends and family, in diaries, and inside longer sentences. One important rule: だ goes after nouns and な-adjectives only. An い-adjective is already a complete plain sentence by itself (高い = "it is expensive"), so you never say 高いだ.
Casual conversation with friends, family and children; plain-style writing such as diaries and novels; and, most importantly for N5, inside sentences before と思う, でしょう, んです and から (学生だと思う "I think he is a student"). In everyday casual speech だ is often dropped: 学生。／ 静か。
Formation
V = verb, N = noun, A = adjective.
Noun + だ (先生だ)な-adjective + だ (静かだ)い-adjective + (nothing) (高い — never 高いだ)Negative: じゃない ／ Past: だった
Visual diagram
| Aspect | Polite | Plain |
|---|---|---|
| Noun | 学生です | 学生だ |
| な-adjective | 静かです | 静かだ |
| い-adjective | 高いです | 高い (no だ) |
Natural examples
田中さんは先生だ。
たなかさんは せんせいだ。
Mr Tanaka is a teacher.
Noun + だ: the casual way to say 先生です.
今日は休みだ。
きょうは やすみだ。
Today is a day off.
休み (day off) is a noun, so it takes だ.
この町は静かだ。
この まちは しずかだ。
This town is quiet.
静か is a な-adjective; it takes だ just like a noun.
あの人は田中さんだと思います。
あの ひとは たなかさんだと おもいます。
I think that person is Mr Tanaka.
Inside と思います you must use the plain だ, even in a polite sentence.
今日は暑い。
きょうは あつい。
It's hot today.
い-adjective: the plain sentence ends with い and nothing else. 暑いだ is wrong.
Similar grammar and the difference
The polite version. Same meaning; です is used with people you are not close to. Compare side by side
The plain negative: "is not". Compare side by side
Not a copula, but the most common place where N5 forces you to use だ: 学生だと思います. Compare side by side
Common mistakes
- ✗
- この店は高いだ。
- ✓
- この店は高い。
- Why
- い-adjectives never take だ. The い ending already makes a complete plain sentence.
- ✗
- 田中さんは学生と思います。
- ✓
- 田中さんは学生だと思います。
- Why
- Before と思う a noun needs だ. Without it the sentence sounds broken to a native speaker.
- ✗
- 先生ですだ。
- ✓
- 先生です。／ 先生だ。
- Why
- です and だ are two versions of the same word; choose one.
In casual speech だ is often dropped entirely (学生。/ 静か。). You must know the plain forms because they appear before と思う, でしょう, んです, and inside relative clauses.
JLPT N5 tips
On the exam
- N5 tests だ mostly indirectly: 〜だと思います, 〜だから, 〜でしょう (no だ!). Learn which patterns need だ and which forbid it.
- If an option adds だ after an い-adjective (おいしいだ, 高いだと思う), it is always wrong.
Frequently asked questions
What does だ (plain copula) mean?
Plain/casual equivalent of です. だ is the plain (casual) version of です. Both mean "is / am / are". You use だ with close friends and family, in diaries, and inside longer sentences. One important rule: だ goes after nouns and な-adjectives only. An い-adjective is already a complete plain sentence by itself (高い = "it is expensive"), so you never say 高いだ.
How do you form だ (plain copula)?
Noun + だ (先生だ) / な-adjective + だ (静かだ) / い-adjective + (nothing) (高い — never 高いだ) / Negative: じゃない ／ Past: だった. V = verb, N = noun, A = adjective.
When is だ (plain copula) used?
Casual conversation with friends, family and children; plain-style writing such as diaries and novels; and, most importantly for N5, inside sentences before と思う, でしょう, んです and から (学生だと思う "I think he is a student"). In everyday casual speech だ is often dropped: 学生。／ 静か。.
What is the difference between だ (plain copula) and です?
The polite version. Same meaning; です is used with people you are not close to.
What is the difference between だ (plain copula) and じゃない?
The plain negative: "is not".
What is a common mistake with だ (plain copula)?
Wrong: この店は高いだ。 Right: この店は高い。 い-adjectives never take だ. The い ending already makes a complete plain sentence.
Quick check
What goes in ( )? 田中さんは 学生（ ）と 思います。