Casual vs Polite Japanese: When to Use Desu/Masu

Japanese has two everyday speech styles: polite speech with です and ます, and casual or plain speech. Every sentence you say uses one or the other, so knowing when to switch is as important as knowing the words. Here’s how the two styles differ, who gets which, and the casual shortcuts you will hear among friends.

Two styles, same meaning

Polite speech (丁寧語 teineigo, often just called です・ます style) ends sentences with です or a verb in its ます form. Casual speech uses plain forms. Japanese speakers call it タメ口 tameguchi or 普通体 futsūtai. The information is the same; what changes is the distance between you and the listener.

Two details trip learners up. In casual speech, だ after a noun is often dropped, and keeping it can sound blunt or assertive in some sentences. And casual questions usually drop か and rely on rising intonation instead: a plain 行くか？ can sound rough.

When to use which

• Polite: people you have just met, shop and restaurant staff, teachers, older people you don’t know well, and almost everyone at work, especially clients and senior colleagues.
• Casual: close friends, family, partners, children, and people of your own age once you’ve become friendly. Classmates and colleagues of similar age may switch to casual quickly in some places and slowly in others.

When in doubt, use polite speech. Being a little too polite rarely causes offence; being casual too early with the wrong person can come across as rude or overly familiar. Expectations vary between workplaces, regions and generations, so watch how the people around you speak to each other.

How to switch

Relationships in Japanese usually start polite and drift towards casual as people get closer. A few things help you judge the moment:

• Follow the other person’s lead. If someone of similar status starts speaking casually to you, you can usually do the same.
• Listen for an invitation. People sometimes say タメ口でいいよ tameguchi de ii yo, “you can talk casually with me.”
• Mixing is normal. Many people speak mostly politely but slip in casual reactions such as そうなんだ sō nan da (oh, really?) or すごい！ sugoi (wow!). This sounds friendly rather than inconsistent.
• Seniority still matters. With someone older or more senior, it is common to stay polite even after you become friendly, while they may speak casually to you.

Common casual contractions

Casual speech also squeezes sounds together. You will hear these constantly in conversation, dramas and anime:

• 〜ている → 〜てる: 何してる？ nani shiteru?, “what are you doing?”
• 〜てしまう → 〜ちゃう: 全部食べちゃった zenbu tabechatta, “I ate it all (oops).”
• 〜ではない → 〜じゃない: 学生じゃない gakusei ja nai, “I’m not a student.”
• 〜なければ → 〜なきゃ: もう行かなきゃ mō ikanakya, “I’ve got to go.”
• 〜ておく → 〜とく: 予約しとく yoyaku shitoku, “I’ll book it (in advance).”
• 〜という → 〜って: 明日休みだって ashita yasumi da tte, “they say tomorrow’s a day off.”

Some of these, like じゃない and 〜てる, also appear inside polite sentences in everyday conversation (学生じゃないです, 住んでます). In formal writing and very formal speech, the full forms are safer.

Where keigo fits in

です and ます are actually one part of keigo, Japanese honorific language. Keigo goes further with respectful verbs that raise the other person, such as いらっしゃる, and humble verbs that lower yourself, such as 申す and 伺う. You need these mainly with customers, clients and senior people at work. For daily life, solid です・ます speech is enough. When you’re ready for the next step, our guide to keigo for work covers the key verbs and phrases.

Practising both styles with a tutor

Textbooks mostly teach polite speech, so many learners understand casual Japanese far better than they can produce it, or the other way round. A native tutor can practise both with you: polite conversation for work and first meetings, and relaxed casual chat like you would have with a friend. At Hanabuddies, online lessons are tailored to the situations you actually face, so you can learn to switch styles naturally.