One of the first things you learn about the Japanese language is “desu” (です). In fact, even those who don’t know Japanese know generally how to use this copula. Just stick it at the end of the sentence and you’re good to go, right?
And for those of us who watched an anime or J-drama episode or two, we’re pretty familiar with the copula “da” (だ), aren’t we? As the textbooks would tell us, these two are supposed to be interchangeable. One is used for formal context and the other for informal ones.
I’m here to tell you that there’s more to them than that, and you won’t find your answers in textbooks. They’re from observation and practice in conversation with local Japanese people – read on to find out what they are!
The Usage of “Desu”
“Desu” (です), as we all know, is used at the end of a sentence to make it formal. This phrase is a copula, so it’s kind of like “to be” (is, am, are) in English. For example, “this is a pen” is said as “kore ha pen desu” (これはペンです). “Desu” is used to link the subject to a subject complement.
When you end a sentence with “desu”, there’s a certain level of formality attached to it. Usually, you would use “desu” when speaking to people who you aren’t familiar with as well as those above you in the work or social hierarchy. If you’re talking to your boss, I’d recommend ending your sentences with “desu”. If you’re talking to your teacher, yup, definitely use it. If you’re talking to your good friend, chances are you don’t have to use it.
“Desu” is attached to nouns and adjectives only. Verbs have their own conjugation that has the same formality as “desu”. Ending a verb with “masu” (ます) is like saying “desu”, but that’s a whole other article altogether.
The Usage of “Da”
Da (だ) is also a copula and acts the exact same way as “desu” most of the time. If you want to say “this is a pen” but using “da” instead, just replace the “desu” with “da”: “kore ha pen da” (これはペンだ). The message is conveyed across just the same.
While “desu” is more formal, “da” is more informal. You often hear it in conversations among good friends, and never with superiors and those you are not familiar with. I would advise you never to use “da” with your boss or teachers. More often than not, guys are the ones using it among themselves. That’s not to say girls don’t say it, too. My girl friends use it, and so do I.
However, “da” is often used in combination with other Japanese particles like “yo” (よ) and “ne” (ね) to make “da yo” (だよ) and “da ne” (だね). Sometimes, you’ll even hear “da yo ne” (だよね) attached at the end of sentences as well as on its own. That’s because, “da” on its own can sound rude and dry in conversation and it’s often used in written form instead of “desu” to imply informality. Using “da yo”, “da ne” and “da yo ne” brings the “da” from cold to casual.
“Da ne” is the most common one of them all, in my opinion. Attaching the “ne” with “da” automatically makes the sentence an engaging one. It’s kind of like asking the other person for their opinion – if they agree or not. If you say “Kono kēki wa oishī da ne” (このケーキを美味しいだね) is like saying “this cake is delicious, isn’t it?”
“Da yo” has a more aggressive tone to it. If you say “watashi da yo” (私だよ), it kind of sounds like “it’s obviously me!” If you’re not so close with someone, it’s best to stay away from this one.
I often use “da yo ne” (だよね) as a response and use it on its own. For example, this phrase is perfect as a response to the cake statement. Saying “da yo ne” to that is you agreeing that the cake is delicious.
The Difference Between “Desu” and “Da”
In textbooks, they’ll tell you that “da” is the informal version of “desu”. That’s pretty accurate. In theory, it is. You can definitely use “da” to make your sentences sound more informal. But make sure you’re also aware that it can also make you sound rude and aggressive.
Using “da” on its own is rather rare in conversation. “Desu”, however, is extremely common. If you’re unsure of what to use at the end of a sentence, it’s never wrong to use “desu”, but it’s not so straightforward with “da”. My advice is to stick with “desu” until you’re comfortable with the various ending particles like “da yo” and “da ne”, or even “yo” and “ne” on their own. Read our Japanese Particles article if you want a clearer picture of what you can use and how to use them.
And there you have it! “Desu” and “da” can seem pretty clear-cut, but it’s not so black and white until you have to actually use it in conversation. I was like that when I first got to Japan, but after countless observations and practice, I now have a better understanding of their usage. Remember, Japanese is a constant learning journey. Good luck!