Table of Contents
The Basics
だ is a little word that packs quite a punch. It is used with nouns and な-adjectives to affirm that they are true, and relevant right here and now. Grammatically speaking, this means it marks these nouns and な-adjectives as present tense and positive (as opposed to negative, or false). In terms of politeness level, だ is associated with the plain form. At the end of a sentence, だ has some nuances that go beyond just casual, depending on the context.
だ for the Positive and the Present
The most basic functions of だ are to mark nouns and な-adjectives as positive (true), and present tense (relevant to now or the future). だ is not used with word types that have their own way of telling us their tense or whether or not they’re true, such as verbs and い-adjectives.
Let’s start by looking at だ with a noun:
- あれは虎だ。
- That is a tiger.
虎 (tiger) is a noun, and when the positive marker だ follows it, it clearly indicates that the statement is true — it is a tiger. If, for some reason, it turned out that the animal is actually not a tiger, だ could be replaced with じゃない to show that it is negative, or not true.
Now let’s take a look at だ with a な-adjective:
- 虎は危険だ！
- Tigers are dangerous!
危険 (dangerous) is a な-adjective, and just like before, だ marks it as positive — yep, tigers are dangerous. Let’s say though, that at some point in the future, all tigers become domesticated, like house cats. If that happens, then we wouldn't use present tense だ to say that tigers are dangerous at this point in time. Instead, we’d switch to the past tense — back in my day, tigers were dangerous. To express this in Japanese, we’d change だ into its past tense form, だった.
Patterns of Use
Broadly speaking, you’ll find だ in about three different places. At the end of sentences, in the middle of sentences, and at the very beginning of sentences, when it’s used as part of a set phrase.
At the End of a Sentence
When だ appears at the end of a sentence, it marks the sentence as plain form, making it appropriate for casual speech. If you want to be polite, you can switch it out with です:
- ミーティングは二時
だ+ です。 - The meeting is at two o’clock.
If the sentence above is spoken in a business context, です would likely be more appropriate than だ. If it was spoken between family or friends, だ might be used, but it would likely be followed up with a conversational particle, such as よ (as in ミーティングは二時だよ). When だ is the last word in a sentence, it can add a sense of surprise, assertiveness, or a whole host of other nuances depending on the context (read about them here, and particles like よ and ね help to downplay them).
In the Middle or Beginning of a Sentence
When だ appears in the middle of a sentence, it means that there are actually two or more clauses within that sentence. A clause is essentially a sentence that exists inside or connected to another sentence.
Let’s start with a sentence-within-a-sentence (i.e. an embedded clause):
- 私は [お金は大切だ] と思います。
- I think [money is important].
In this sentence, you can see だ at the end of 「お金は大事だ」. This itself is a full sentence, but in this case it’s embedded inside a larger sentence. It’s followed by particle と, which is sort of like a spoken quotation mark, and the verb 思います (think). In other words, お金は大切だ (money is important) is what I think.
When だ appears at the end of an embedded clause, it has no effect on politeness level. This is because politeness is only marked at the end of the main clause in Japanese. In this case, the 〜ます ending on the verb 思います indicates that the sentence is polite.
Next, let’s look at a sentence with two clauses that are not embedded, but joined together into one sentence:
- [A: お金は大切だ]–から–[B: 仕事は必要だ]。
- Because money is important, jobs are necessary.
This sentence has two clauses, and they are connected together by the particle から. から tells us that the first clause is the reason for the second clause, similar to the word “because” in English. から is part of a group of conjunctive particles that connect clauses together, such as が and けど.
Sometimes, you will find だ at the very beginning of a sentence as well, in combination with these conjunctive particles:
- だから、大学に行きなさい。
- For that reason, you should go to college.
Imagine your mom saying this sentence right after the last example sentence about jobs and money. だから is used to refer to the previous sentence, and say that is the reason for what comes next. だが and だけど are both used at the beginning of sentences well, to mean something like “however” in English.
Beyond the Basics
Nuances of だ
When だ is used at the end of spoken sentence or a casual written message (such as a text), it can add some pretty strong overtones. This is because sentence final だ is actually an optional element. Let’s check it out:
- 猫が嫌いだ！
- I hate cats!
- 猫が嫌い！
- I hate cats!
Both of these are grammatically acceptable sentences with the same English translation, but they each have a different nuance. The first sentence, which includes だ, feels like a very strong exclamation that you HATE cats. The second sentence is a bit more neutral, like you’re just stating a simple fact about your pet preferences. Why is this?
Remember, the most basic function of だ is to mark a noun or な-adjective as present tense and positive. However, when だ is omitted, we still assume that the sentence is present tense and positive, since there’s nothing to mark them as past tense (like だった) or negative (like じゃない). In other words, sentences in Japanese are present tense and positive unless proven otherwise. So in a way, だ is a little bit redundant, and therefore it emphasizes that you really mean what you’re saying.
Don’t be afraid to use だ when speaking Japanese, though. When you dress it up with よ or ね, it doesn’t sound assertive at all. Similarly, grammar constructions that end in だ, such as 〜んだ do not sound particularly assertive either. In fact, dropping だ a lot will result in a very feminine quality to your speech. For example, そうだよ sounds gender neutral or perhaps mildly masculine, whereas そうよ sounds feminine, through and through.
In formal writing, だ takes on a totally different vibe than in speech. Rather than sound assertive, it actually sounds somewhat neutral and objective. This is because, to sound more sure-of-yourself in writing, だ is often switched out for である. If you’re interested in learning more about the nuances of だ (and です) in spoken and written Japanese, read our article about it.
Common Mistakes
Using だ with い-adjectives and Verbs
The basic function of だ is to mark the preceding word as present tense and positive, so it can’t be used with words that can do all this themselves through conjugation, like い-adjectives and verbs.
This gets tricky though, since です, the cousin of だ, can occur with these words, since it is just a marker of politeness:
❌ おいしいだ
⭕ おいしいです
❌ 行かないだ
⭕ 行かないです
Don’t let the fact that です is ok after negative plain form verbs and い-adjectives fool you. だ is not ok here!
だから With い-Adjectives
Remember that だ can be used in the middle of a sentence alongside a conjunctive particle, like から or けど? As in:
- [A: お金は大切だ]–から–[B: 仕事は必要だ]。
- Because money is important, jobs are necessary.
In the example sentence above, clause A ends in the な-adjective 大切 (important), and な-adjectives are one of the words だ is typically used with.
If clause A ended in an い-adjective though, using だ would not be ok:
- [A: ❌お金がほしい
だ]–から–[B: 仕事は必要だ]。 - Because I want money, jobs are necessary.
“Want” in Japanese is an い-adjective — ほしい. Perhaps a more literal translation of ほしい would be “desireable.” In any case, clause A ends in an い-adjective, so だ would be ungrammatical to add in before から. This is because the 〜い ending of い-adjectives tells us that the word is present tense and positive. When a word can do this itself (such as if it’s a verb or an い-adjective), だ cannot be used.
Learners of Japanese often memorize だから as a set phrase that means “because”. Just remember that it is a phrase, and だ must be removed when used immediately after an い-adjective or verb. Same goes to other conjunctive particles such as が and けど.