Table of Contents
The Basics
です is one of the most fundamental words in the Japanese language. It’s super useful — it can be attached to just one other word to form some basic sentences. It’s also quite safe to use since it’s part of the polite form, so you’re unlikely to offend someone with this word.
です as a Politeness Marker
The most fundamental function of です is to mark a sentence as polite. You might be tempted to think of it as the polite form of だ, but these two words have some pretty big differences. Put simply, だ marks sentences as present tense and positive, whereas です is really just a simple marker of politeness.
Patterns of Use
です is found at the end of sentences, where it marks the sentence as polite.
です With Nouns and Adjectives
です can be tacked onto the end of a noun, な-adjective, or い-adjective to form a polite, positive, present tense sentence (say that ten times fast 😉). In other words, it allows us to talk about something that is true, and relevant to the present moment and/or the future—all in a polite way of course. Let’s take a look:
- 私は萌子です。
- I am Moeko.
While 「私は萌子。」 is also a grammatically acceptable sentence in Japanese, it sounds a bit childish without our trusty です added to the end. です is added to make the sentence sound polite and socially aware, which is something you’d generally do when introducing yourself.
When used with common nouns, like natto, everyone’s favorite stinky soy bean dish, です adds a polite, presentational tone to a sentence:
- はい、納豆です。
- Ok, here’s the natto.
Imagine someone handing you a bowl of natto and speaking this sentence. While they could simply say はい、納豆, adding です makes the sentence sound more respectful and polite.
です can also be used after adjectives that describe the subject of a sentence:
With a な-adjective:
- 納豆は健康的です。
- Natto is healthy.
With an い-adjective:
- 納豆はまずいです。
- Natto is unpleasant.
In the first sentence, the な-adjective 健康的 (healthy) describes the subject of the sentence (納豆), and the い-adjective まずい (unpleasant) in the second sentence does the same thing. Just like with nouns, the meaning that です adds to these sentences is a feeling of politeness and social engagement.
です with Negative Marker ない
です can be used with ない, a word that marks words as negative, or not true. This is one of the reasons that we say です is not the polite form of だ, and that they are inherently different words. だ tells us that a statement is positive, or true. For this reason だ is contradictory to ない, and can’t attach to it.
です on the other hand makes no claims about being true or false, it simply tells us that the sentence is polite. For this reason, it can follow any word marked with ない, whether it’s a noun, な-adjective, い-adjective, or even a verb.
ない marks nouns and な-adjectives negative as part of a phrase, like じゃない. です can follow this to indicate the sentence is polite:
- トマトは野菜じゃないです。
- Tomatoes are not vegetables.
- このトマトは新鮮じゃないです。
- This tomato is not fresh.
い-adjectives also use ない to become negative by conjugating to the 〜くない ending. Here too, です can be used to mark politeness.
- 納豆はまずくないです。
- Natto is not unpleasant.
In the negative plain form of verbs, verbs conjugate to end in ない, showing that they are negative. です is able to mark politeness here too.
- 私達は納豆を食べないです。
- We don’t eat natto.
However, it’s good to know that, while polite, the 〜ないです ending of verbs is considered more colloquial, and less “proper” than the polite form verb ending 〜ません. Still, it is widely used in spoken Japanese and some informal writing as well.
です With Past Tense Marker 〜かった
です can be used with 〜かった, the past tense form of い-adjectives. This is the second reason that we think of です and だ as quite different from one another—だ marks a sentence as present tense, so using it after 〜かった is not possible.
Meanwhile, the only function of です is to mark for politeness, so it does not contradict the past tense 〜かった form. For this reason, です can be used with past tense い-adjectives, as well anywhere the past tense of ない pops up, such as with nouns, な-adjectives, and verbs.
です can appear after a positive past tense い-adjective:
- 昨日の納豆は美味しかったです。
- The natto from yesterday was delicious.
です can also be be used after a negaitve past tense い-adjective:
- でも、その前の日の納豆は美味しくなかったです。
- But, the natto from a day before yesterday was not delicious.
です can be used after the past tense form of ない, whether it crops up with nouns, な-adjectives, or verbs.
With a negative, past tense noun:
- それは納豆じゃなかったです。
- That was not natto.
A negative, past tense な-adjective:
- 納豆を食べる前は、元気じゃなかったです。
- Before eating natto, I was not well.
With a negative, past tense, plain form verb:
- あら、納豆がない！昨日は買いに行かなかったです。
- Oh no, there’s no natto! I did not go to buy any yesterday.
Just like we mentioned before with the present tense 〜ない ending of verbs, adding です to the past tense 〜なかった ending is not considered to be as proper as using the ます form. Traditional grammarians would argue that 〜ませんでした is the preferred way of making a verb polite, negative, and past tense, but it’s true that 〜なかったです is frequently used spoken Japanese.
Since です can occur with the past tense い-adjectives and verbs, you should be able to see that it is not inherently a present tense marker. That being said, it’s important to know that です does have a past tense form itself, which is でした. When you want to mark a word as past tense that cannot be conjugated on its own (like a noun or な-adjective), then でした comes in very handy.
Beyond the Basics
です in the Middle of a Sentence
When です 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):
- コウイチは 「納豆はおいしいです」 と言いました。
- Koichi said “Natto is delicious.”
In this sentence,「納豆はおいしいです」is a direct quote. It is exactly what Koichi said, word-for-word. This quote is called an “embedded clause” because it exists inside the larger, main clause,「コウイチは…と言いました」. です can appear at the end of an embedded clause if it is a direct quote, but it cannot be used at the end of any other embedded clause. For example:
- [納豆が健康的
ですだ] と世界中の皆さんに伝えたいです。 - I want to tell the people of the world [that natto is healthy].
In this sentence,「納豆が健康的だ」is not a direct quote of anyone, it is simply the message that you want to convey to the world. You probably won’t use those exact words to convey the message, so this clause just represents your idea or intention. Since です can only be used in embedded clauses that are direct quotes, this one needs to end with だ. Despite the plain form だ popping up, this sentence is still polite overall. This is because です appears at the end of the main clause, after the verb 伝えたい (want to tell).
Another reason です might appear in the middle of a sentence is if there are two clauses that are not embedded, but joined together into one sentence:
- [A: 健康は第一です]–から–[B: 納豆は人気です]。
- Health is top priority, so natto is popular.
In this example sentence, there are two clauses, [A: 健康は第一です] and [B: 納豆は人気です], which could stand on their own as independent sentences. They are connected by から, which tells us that clause A is the reason for clause B. から is part of a group of conjunctive particles that connect clauses together, such as が and けど, and ので.
Because clause A and clause B would become independent sentences if から was removed, it is possible for both clauses to have different politeness levels. In the example above, they are the same; both marked as polite by です at the end of each clause. However, it would be grammatical to change the ending of clause A to the plain form using だ, and then mark clause B as polite with です:
- [A: 健康は第一だ]–から–[B: 納豆は人気です]。
- Health is top priority, so natto is a treasure.
Even though clause A is marked with だ, this sentence feels polite overall, because the ending of the entire sentence is the most potent marker of politeness. While we can have clause A in the plain form and clause B in the polite form, the reverse is not possible:
- ❌[A: 健康は第一です]–から–[B: 納豆は人気だ]。
- Health is top priority, so natto is a treasure.
It’s possible that someone could say this sentence in spoken Japanese for some reason, but it is definitely awkward to have the first clause more polite than the second. In general, you should avoid putting the polite clause before the plain form clause.
Common Mistakes
です is used to mark words as polite only if they do not have their own way of conjugating to show politeness themselves. So while です is used with the negative 〜ない form of verbs, it is not used with them in any other formation, since these can be conjugated to show politeness themselves with the 〜ます ending.
行く (go) → ⭕ 行きます / ❌ 行くです
行った (went) → ⭕ 行きました / ❌ 行ったです