# ことにする: to decide to > Learn how to use ことにする, a JLPT N4 Japanese grammar point meaning to decide to, with structure, nuance, examples, mistakes, and comparisons. JLPT level: N4 · Updated: 2026-05-17 · Canonical: https://hane-app.com/blog/n4-koto-ni-suru/ **ことにする** means **to decide to**. It is a **JLPT N4** Japanese grammar pattern used to say that the speaker decides to do something. This grammar point often appears in conversation, written explanations, formal notices, and JLPT-style reading questions. If you want to say that the speaker decides to do something, **ことにする** is a useful pattern to learn after the N5 basics. ## What does ことにする mean? Use **ことにする** when you want to say that the speaker decides to do something. Natural translations include: - to decide to The exact English translation changes with context. Focus on what the grammar point does in the sentence first, then choose the English phrase that sounds natural. ## How to form ことにする

Verb (dictionary form / ない form) + ことにする

Examples of the pattern: - 行くことにする - 買わないことにする - 勉強することにする Pay attention to the word form before the pattern. Many JLPT N4 mistakes happen because the meaning is understood, but the grammar is attached to the wrong form. ## When is ことにする used? Use **ことにする** in situations like: - explaining a condition, reason, decision, or time relationship - making a sentence more specific than a basic N5 pattern - understanding natural Japanese in conversation or reading Tone and register: - neutral unless the grammar itself is marked as casual, humble, honorific, or formal - Common in daily speech, textbook examples, and JLPT N4 reading questions ## ことにする example sentences

毎日まいにち日本語にほんごを勉強べんきょうすることにしました。

I decided to study Japanese every day.

polite affirmative

今日きょうは早はやく寝ねることにします。

I will decide to sleep early today.

polite affirmative

新あたらしいパソコンは買かわないことにしました。

I decided not to buy a new computer.

polite negative

週末しゅうまつに友達ともだちと会あうことにしました。

I decided to meet my friend on the weekend.

polite affirmative

バスではなく電車でんしゃで行いくことにします。

I will decide to go by train, not bus.

polite affirmative

Read the Japanese sentence first, then check the English translation. Try to notice what the grammar point contributes: condition, timing, limitation, possibility, decision, politeness, or emphasis. ## Nuance of ことにする The key nuance is **focuses on the speaker’s own decision**. This matters because **ことにする** may look simple in English, but the Japanese form tells you whether the speaker is describing a time, a condition, a decision, a possibility, or a social relationship. For example: - In context, **ことにする** helps make the sentence more precise than a direct English translation. - Compared with **ことになる**, it has a different focus even when both patterns appear in similar sentences. ## ことにする vs ことになる Both **ことにする** and **ことになる** can appear in related sentences, but they are different.

ことにする

The target JLPT N4 pattern in this lesson

Carries the specific nuance explained above

毎日まいにち日本語にほんごを勉強べんきょうすることにしました。

I decided to study Japanese every day.

ことになる

Useful for comparison because learners often mix it up

May use a different form, tone, or sentence focus

Compare the form and ask whether the sentence is about timing, condition, ability, decision, or politeness.

Related pattern with ことになる

Quick contrast examples: - Target pattern: 毎日まいにち日本語にほんごを勉強べんきょうすることにしました。 — I decided to study Japanese every day. - Related pattern with **ことになる**: compare the form and ask whether the sentence is about timing, condition, ability, decision, or politeness. If you are unsure which one to use, identify the main job of the sentence before translating it into English. ## Common mistakes with ことにする

❌

Using it with the wrong verb, noun, or adjective form

✅

Attach ことにする to the dictionary form or the ない form only

❌

Confusing it with ことになる because the English translation can look similar

✅

Check who makes the decision before choosing between ことにする and ことになる

❌

Translating it too literally instead of reading the whole sentence context

✅

Read the full context to confirm the grammar point shows a speaker decision

A good study habit is to write one short sentence and then change only the grammar point. This makes the difference between similar patterns easier to feel. ## Is ことにする on the JLPT?

ことにする is commonly taught as JLPT N4 grammar.

recognize it in reading
understand its nuance in context
use it in simple original sentences

For test preparation, do not only memorize the English gloss. Practice identifying the words around the grammar point, because JLPT questions often test structure and context together. ## Practice questions for ことにする

Write one sentence using the basic pattern.

production

Change the sentence into polite or casual style if possible.

Compare it with the related pattern from the comparison section.

comparison

Keep the sentences short at first. Once the form feels natural, add time words, places, reasons, or contrast to make the sentence more realistic. ## Learning path for ことにする Use **ことにする** as part of your **JLPT N4** change, decision, and intention grammar toolkit. Track who controls the change or decision in **ことにする**. Some patterns show natural change, some show personal effort, and others show a decision made by someone or by circumstances.

Make one short sentence with ことにする.

Compare it with 予定だ.

Add ぜひ or ようになる to see how the nuance changes.

Write one sentence that uses ことにする in its most literal meaning, one sentence that changes the subject or time expression, and one sentence that contrasts it with one of the related patterns below.

## Related grammar to review next - [予定だ](/blog/n4-yotei-da/) — connects to change, decision, planning, or effort over time. - [ぜひ](/blog/n4-zehi/) — connects to change, decision, planning, or effort over time. - [ようになる](/blog/n4-you-ni-naru/) — connects to change, decision, planning, or effort over time. - [ようにする](/blog/n4-you-ni-suru/) — connects to change, decision, planning, or effort over time. ## Learn ことにする with Hane If you want to review **ことにする** together with the related patterns above, Hane helps you practice Japanese in short, focused sessions. Browse more lessons here: - [All grammar lessons](/blog/) - [JLPT N4 grammar lessons](/blog/n4/)