Japanese Desu Masu Form: Complete Guide to the Conjugation and Grammar of Polite Forms

When you start to learn Japanese, one of the first things you'll encounter is the です・ます (desu/masu) form. This is basically the foundation of polite Japanese, and honestly, you'll use it with people you don't know well, at work, in stores, with teachers, and pretty much any situation where you want to sound respectful without being overly formal. Here's your complete guide on how to use them!

Understanding politeness levels in Japanese

The desu/masu form represents what we call the polite form in the Japanese language. This sits between casual speech (using だ and plain verb forms) and more formal or honorific speech (keigo).

When should you use the polite form? Pretty much all the time when you're starting out. Use it with:

You'd switch to casual forms with close friends, family members, or people younger than you in casual settings. But honestly, sticking with desu/masu forms is always safe when you're unsure.

What exactly is です (Desu)?

Let's start with です. This little word functions as what linguists call a copula, which is basically a word that links a subject to a description or identity. Think of it like the verb "to be" in English.

You use です after nouns and adjectives to make your sentences polite. The basic pattern looks like this:

For example:

The particle wa (written as は but pronounced "wa") marks the topic of your sentence, and です comes at the very end to make everything polite. Without です, you'd have the casual form だ (da), which you'd use with close friends or family.

Conjugating です

The desu conjugation is pretty straightforward. Here are the main forms you need to know:

Examples:

One thing that confuses beginners: when you use an i-adjective (like = hot), you conjugate the adjective itself and then add です. The です here adds politeness but doesn't really change the grammatical meaning. So uses the adjective in its plain form plus です for politeness.

What about ます (Masu)?

Now for ます (masu). This one attaches to verbs to make them polite. While です works with nouns and adjectives, masu is specifically for verb conjugation.

To use masu, you need to convert your verb to what's called the masu-form or conjunctive form. This involves taking the dictionary form of the verb and changing it to the stem that masu attaches to.

For example:

How to make verbs polite with ます

Japanese verbs fall into three groups, and each has slightly different rules for forming the masu stem:

Group 1 (u-verbs): Change the final u-sound to an i-sound, then add ます

Group 2 (ru-verbs): Drop the る (ru) and add ます

Group 3 (irregular verbs): Just memorize these

Conjugating ます forms

The masu conjugation gives you several useful forms:

Examples:

The masu form handles both present and future tense, which makes things simpler than English in some ways. Context usually makes it clear whether you're talking about now or later.

The key difference between です and ます

So what's the actual difference between using masu and desu? This trips up a lot of beginners, but the answer is pretty simple once you get it.

You can think of です as the polite copula (the "is/am/are" equivalent), while ます is the politeness marker for action verbs.

Here's where it gets interesting: you can actually use both in the same sentence. For example:
。
I am a student and study every day.

The で (de) here is the conjunctive form of です, connecting two clauses. The first clause uses the noun (Student), and the second clause uses the verb (To study) in its masu form.

What about using casual form plus です?

Some learners ask about the difference between using ます and using the casual verb form plus です. Here's the deal: you generally don't mix them in standard Japanese.

However, you might occasionally hear constructions like , which uses the explanatory ん (n) plus です. This is grammatically correct and adds a nuance of explanation or emphasis. But just slapping です onto a casual verb form without any other grammar doesn't work.

Mid-sentence usage and advanced tips

Once you get comfortable with basic desu/masu usage, you'll encounter situations where these forms appear in the middle of sentences, connected by conjunctive particles or clause markers.

The conjunctive form of です is で (de), which you use to connect clauses:
。
Today is Monday and I'm busy.

For verbs in masu form, you can use the masu stem (without the ます part) as a conjunctive form to connect actions:
。
I wake up in the morning, take a shower, and eat breakfast.

Notice how the final verb gets ます but the earlier verbs use the て-form. This is standard: you only need to mark politeness at the end of the sentence in most cases.

Common mistakes and how to avoid them

Let me share some mistakes I see beginners make all the time with the desu/masu form:

Mistake 1: Forgetting です or ます entirely Beginners sometimes drop the polite ending because they're thinking in English. In Japanese, you need that polite marker when speaking formally.
Wrong: in a polite context
Right: 。

Mistake 2: Using です with verbs Remember, です goes with nouns and adjectives, not verbs.
Wrong:
Right:

Mistake 3: Double-marking politeness You don't need both masu and desu on the same verb.
Wrong:
Right:

Mistake 4: Wrong adjective conjugation With i-adjectives, you conjugate the adjective and then add です. With na-adjectives, you just add です directly.
I-adjective: (Expensive) → NOT
Na-adjective: (Quiet) →

Mistake 5: Mixing politeness levels Try to stay consistent within a conversation. Don't jump between casual and polite forms randomly.

Why this matters for learning Japanese

Mastering the desu/masu form gives you the ability to communicate respectfully in Japanese from day one. You can have real conversations, ask questions, make requests, and express yourself without worrying about being rude.

The conjugation patterns are regular and predictable once you learn them. Unlike some aspects of Japanese grammar that have tons of exceptions, desu/masu forms follow clear rules. You learn the pattern once, and you can apply it to thousands of verbs, nouns, and adjectives.

Plus, understanding politeness levels helps you grasp Japanese culture better. The language reflects the importance of social relationships and context. Being able to adjust your speech based on the situation shows cultural awareness and respect.

As you progress, you'll learn more casual forms, honorific language, and humble language. But the desu/masu form remains your reliable default for polite, everyday Japanese. Even advanced speakers use it constantly.

Anyway, if you want to practice recognizing desu/masu forms in real Japanese content, Migaku's browser extension and app let you look up words and grammar patterns instantly while watching shows or reading articles. You can see these forms in context and build your understanding naturally. There's a 10-day free trial if you want to check it out.

FAQs

Train yourself to get used to the polite nuances

Rome is not built in one day, so is your Japanese progress! It's a major shift in mindset to adjust from English to the Japanese polite culture. If you enjoy Japanese dramas and anime, you can always resort to these media to get used to how Japanese people talk in polite and casual forms!

Learning is a lifelong process!