する vs やる: The Difference Between “Do,” “Play,” “Try,” and Casual Action in Japanese

You are talking to a Japanese friend and you want to say “I’m doing my homework.” You know the word for homework — 宿題（しゅくだい）. And you know there is a verb for “do.” But then you remember: there are actually two verbs that mean “do” in Japanese — する and やる. Which one do you use?

This is one of those small gaps that trips up English speakers at the N5–N4 level. In English, “do” covers everything. In Japanese, する and やる share the same core meaning, but they carry different registers and rules. Get them mixed up and you might sound too stiff in casual conversation — or, worse, too rough in a formal setting.

This guide explains exactly when to use する, when to use やる, and why the safest rule for beginners is simply: when in doubt, use する. It is always acceptable. やる is a tool you add once you are confident the situation is casual.

Quick Answer: する vs やる

Here is the short version before we dive deeper.

• する is the neutral, all-purpose “do.” It works in every situation: polite speech, formal writing, business contexts, and everyday casual talk. It is also the verb that fuses with hundreds of nouns to make compound verbs like 勉強する（べんきょうする）, 予約する（よやくする）, and 運動する（うんどうする）.
• やる is the casual, colloquial “do.” It has the same core meaning as する but sits lower on the register scale. It is very natural for sports, games, hobbies, chores, and homework — especially with friends and family.
• Beginner rule: default to する every time. It is never wrong. Start using やる once you have a feel for casual contexts and can recognise when the situation calls for it.
• Key difference in one sentence: する is the standard verb; やる is what your friends use at home.

What Does する Mean?

する（する）is arguably the most versatile verb in Japanese. It can mean “do,” “make,” “play,” “have,” “feel,” and more depending on context. Its polite form is します（します）.

Its most important role, however, is as the engine behind hundreds of compound verbs. When a Japanese noun combines directly with する — with no particle between them — the two words fuse into a single verb unit:

• 勉強する（べんきょうする）— to study
• 仕事をする（しごとをする）— to work / do one’s job
• 運動する（うんどうする）— to exercise
• 予約する（よやくする）— to make a reservation
• 連絡する（れんらくする）— to contact / get in touch

In polite and formal Japanese — business emails, speaking with teachers or strangers, customer service — する (and its polite form します) is the expected choice. It is safe, standard, and appropriate everywhere.

Here are four natural example sentences using する:

1. 毎日、運動をします。（まいにち、うんどうをします。）
I exercise every day.

2. 明日、会議の予約をします。（あした、かいぎのよやくをします。）
I will make a reservation for the meeting tomorrow.

3. 宿題をしてから、ご飯を食べます。（しゅくだいをしてから、ごはんをたべます。）
I will eat after doing my homework.

4. 何かスポーツをしますか？（なにかスポーツをしますか？）
Do you play any sports?

What Does やる Mean?

やる（やる）shares する’s core meaning of “do,” but it registers as casual and colloquial. Think of it as the version your Japanese friends use at home, in texts, or among classmates — not the version you use in an email to your boss.

やる is especially common for:

• Sports and active hobbies: スポーツをやる, 野球をやる（やきゅうをやる）, 剣道をやる（けんどうをやる）
• Games: ゲームをやる, カードゲームをやる
• Homework and tasks: 宿題をやる（しゅくだいをやる）, 課題をやる（かだいをやる）
• Instruments: ギターをやる — “to play guitar” (casually)

やる has a polite form: やります（やります）. But even in polite form, やります carries a slightly casual or rough feel compared to します. For that reason, in truly formal contexts — business presentations, speaking with customers, formal writing — します is the safer, more appropriate choice.

Here are four natural example sentences using やる:

1. 週末、友達と野球をやる。（しゅうまつ、ともだちとやきゅうをやる。）
I’m going to play baseball with friends this weekend.

2. 宿題、もうやった？（しゅくだい、もうやった？）
Did you do your homework yet?

3. 最近、ギターをやっているんだ。（さいきん、ギターをやっているんだ。）
I’ve been playing guitar lately.

4. そのゲーム、やったことある？（そのゲーム、やったことある？）
Have you ever played that game?

する and やる in Daily Conversation: Side-by-Side

For many everyday activities, you can use either する or やる — but one will often feel more natural depending on the situation. Here is a direct comparison:

The pattern here is clear: when the activity is physical, recreational, or part of daily casual life (games, homework, sports), やる fits naturally. When the activity edges toward work, professional settings, or general conversation with people you do not know well, する is the safer and more expected choice.

する Compound Verbs That Should Stay する

This is the section that saves beginners from their most common mistake with やる.

In Japanese, many nouns fuse with する to create a single compound verb. The する in these words is part of the verb itself — it is not a separate “do” that you can swap out. Common examples:

• 結婚する（けっこんする）— to marry → not 結婚をやる
• 予約する（よやくする）— to reserve → not 予約をやる
• 説明する（せつめいする）— to explain → not 説明をやる
• 連絡する（れんらくする）— to contact → not 連絡をやる
• 確認する（かくにんする）— to confirm → not 確認をやる
• 相談する（そうだんする）— to consult / discuss → not 相談をやる

The rule is this: if there is no を between the noun and する, the two have fused into one compound verb — do not replace する with やる.

If there is a を between the noun and する — as in 宿題をする — then やる is often a natural swap in casual speech: 宿題をやる.

Yuka

Wait, so I was wrong to say 予約をやる? I used that in a message to the hotel last week!

Rei

Exactly — 予約する is a fused compound verb. The する is locked in. You cannot swap it to やる. In formal messages especially, stick with 予約します. The hotel staff would likely still understand you, but it sounds unnatural and a little rough for that context.

When やる Sounds Natural

So when should you reach for やる? There are some situations where it is the genuinely more natural choice — especially in casual spoken Japanese.

Sports and active hobbies:

• 野球をやっている（やきゅうをやっている）— I play baseball (ongoing)
• 剣道をやってみたい（けんどうをやってみたい）— I want to try kendo
• ギターをやっている（ギターをやっている）— I’m learning guitar / playing guitar

Grammar patterns where やる shines:

• やってみる — “give it a try” / try doing something. [Verb て-form + みる = try doing.] やって + みる = try it out. This is extremely common in casual speech. Example: とりあえず、やってみよう。
  Let’s just give it a try for now.
• やっておく — “get it done in advance” / do it and leave it ready. [Verb て-form + おく = do in preparation.] Example: 明日の分、今日やっておくね。
  I’ll get tomorrow’s stuff done today.
• やっている — “currently doing” (casual ongoing action). Example: 今、宿題やってるから、後でね。
  I’m doing homework right now, so talk later.
• やってしまう — “go ahead and do it” or “accidentally do.” Example: もうやってしまった。
  I already went ahead and did it.

Note: してみる, しておく, している, and してしまう all work grammatically — and they are perfectly natural too. The difference is that the やって + pattern combinations often carry a slightly more casual, energetic tone that fits everyday spoken Japanese very well.

Yuka

Do people really use やる in emails? I wrote やります in a message to a teacher once and I’m not sure if it was okay.

Rei

That is something I learned the hard way too. Even やります, the polite form, still has a slightly rough or casual feel. For a teacher or anyone you want to show respect to, します is much safer. Save やります for friends and family — and even then, you often just use the plain form やる.

する vs やる in School, Work, and Hobbies

Let’s look at how register shifts depending on your environment.

At school:
宿題をやる（しゅくだいをやる）is perfectly fine among classmates. But if you are talking to a teacher — “I will do my homework” — you should say 宿題をします or 宿題をやります at minimum, and 宿題を提出します（ていしゅつします）if you want to be more precise and respectful. For class presentations: 発表をします（はっぴょうをします）— する is the standard here, not やる.

At work:
In professional settings, する is your default for almost everything. 確認をする（かくにんをする）, 準備をする（じゅんびをする）, 説明をする（せつめいをする）— all standard, expected, and safe. やる sounds too casual for business communication. One note: メールをする is somewhat unusual in natural Japanese — you would more naturally say メールを送る（おくる）, “send an email,” rather than “do an email.”

Sports and hobbies:
This is where やる feels most at home. 趣味でギターをやっています（しゅみでギターをやっています）is a very natural way to say “I play guitar as a hobby.” スポーツをやっている and スポーツをしている are both widely used — neither sounds wrong. Context and personal style determine which one comes out naturally.

The key insight: naturalness is not determined by a fixed rule but by the combination of the activity, the relationship between speakers, and the setting. A casual conversation about hobbies calls for casual language; a business context calls for standard or formal language. する covers all contexts safely; やる shines in the casual half.

Common Mistakes English Speakers Make

• Using やる in a business email or formal message. Even if you know やる, the moment you drop it into a formal context it sounds rough or careless. Always use する (します) in writing to teachers, bosses, or anyone you address politely.
• Turning every する compound verb into やる. This is the big one. 予約をやる, 説明をやる, 連絡をやる — these all sound unnatural or wrong because the する in those words is fused and not swappable. The を test helps: if there is no を, the compound is fused — keep する.
• Not noticing that やる has a register. Many textbooks introduce する as “the verb for do” and some learners reach N4 without realising やる exists or is extremely common in casual spoken Japanese. Listening to native Japanese conversation, you will hear やる constantly in informal settings.
• Avoiding やる entirely and sounding stiff. The opposite problem: knowing やる sounds casual, some learners avoid it entirely and always use する — even in texts to close friends. While never incorrect, it can make your Japanese sound a little formal or textbook-stiff in casual contexts.
• Thinking してみる and やってみる are interchangeable in all situations. Grammatically both work. But やってみる is the go-to casual form when “give it a try” energy is what you want to convey. してみる is slightly more neutral. Neither is wrong — but knowing which feels more natural in speech is part of levelling up.

Yuka

Okay, I definitely made the 予約をやる mistake before. At least it sounds like the rule “when in doubt, use する” really does cover most situations?

Rei

Exactly right. する covers you in probably 90% of everyday situations without ever sounding wrong. Once you get comfortable with casual conversation and you can feel when the moment is relaxed, start experimenting with やる. It will start to feel natural quickly — especially with things like 宿題やった？ and やってみよう.

Decision Rule: する or やる?

Use this flowchart whenever you are not sure which verb to reach for:

Is it a fused compound verb (noun + する, no を between them)?
  YES → Always use する
        (e.g., 勉強する, 予約する, 説明する, 連絡する, 確認する)

Is it a noun + を + する/やる?
  → Both can work for casual, everyday activities
  → Use する in formal or polite situations
  → やる is natural casually (宿題をやる, ゲームをやる, スポーツをやる)

Are you speaking or writing formally?
  (business, teachers, strangers, emails, presentations)
  → Always use する / します

Are you using a grammar pattern (〜てみる, 〜ておく, 〜ている, 〜てしまう)?
  → Both する and やる forms work
  → やって + pattern sounds naturally casual
  → して + pattern is neutral and safe everywhere

Still not sure?
  → Use する — it is always acceptable

Quick Quiz: する or やる?

Test yourself with these five questions. Choose the more natural option and check your answers below.

Q1. 友達と＿＿テニス。(する / やる)

Q2. 明日、先生に連絡を＿＿。(します / やります)

Q3. 宿題、もう＿＿？(した / やった)

Q4. この仕事、ちょっと＿＿みる。(して / やって)

Q5. 会議の前に必ず確認を＿＿。(する / やる)

Answers

A1. やる — Playing tennis with friends is a casual, active, social context. Both する and やる are grammatically fine here, but やる is the very natural choice among friends. ✅

A2. します — 連絡する（れんらくする）is a fused compound verb. You cannot swap する out for やる. And because you are contacting a teacher, the polite form します is correct. 連絡をやります sounds wrong in any context. ✅

A3. やった — This is casual spoken Japanese between friends or classmates. 宿題をやる is very natural here. やった？ (past casual) is the common form you will hear constantly among students. ✅

A4. やって — やってみる is the more natural colloquial form for “give it a try.” してみる also works and is grammatically correct, but in everyday spoken Japanese やってみる is the expression you will hear most often. ✅

A5. する — 確認する（かくにんする）is a fused compound verb used in professional and semi-formal contexts. する is locked in here. 確認をやる sounds unnatural and would raise eyebrows in a meeting room. ✅

Have you ever accidentally used 予約をやる in a formal message — or caught yourself always using する even in texts with close friends? Share your experience in the comments below. It helps other learners to hear real examples of how these verbs trip people up!

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