# に決まっている: it must be; surely > Learn how to use に決まっている, a JLPT N2 Japanese grammar point meaning it must be; surely, with structure, nuance, examples, mistakes, and comparisons. JLPT level: N2 · Updated: 2026-05-06 · Canonical: https://hane-app.com/blog/n2-ni-kimatte-iru/ **に決まっている** means **it must be; surely**. It is a **JLPT N2** Japanese grammar pattern used to **express strong certainty based on assumption or attitude**. This grammar point often appears in advanced reading, formal writing, notices, essays, and careful conversation. If you want to read Japanese with more nuance, **に決まっている** is a useful pattern to learn because it shows the speaker's logic, stance, or emphasis. ## What does に決まっている mean? Use **に決まっている** when you want to **express strong certainty based on assumption or attitude**. Natural translations include: - it must be; surely - depending on context - in a way that matches the speaker's emphasis The best translation depends on the sentence. Focus first on what relationship the pattern creates between the ideas. ## How to form に決まっている Plain form + に決まっている Examples of the pattern: - 彼なら合格するに決まっている。 - こんなに安いなら - 何も準備していないのだから In JLPT questions, pay close attention to the word immediately before the grammar point. Many wrong answers use a similar meaning but attach to the wrong form. ## When is に決まっている used? Use **に決まっている** in situations like: - reading formal explanations, announcements, or essays - making a point more precise than a basic grammar pattern would - connecting two ideas with a clear nuance Tone and register: - usually neutral to formal - common in JLPT N2 reading passages, news, notices, and business-like writing ## に決まっている example sentences - 彼なら合格するに決まっている。 — If it's him, he is sure to pass. - こんなに安いなら、すぐ売り切れるに決まっている。 — If it's this cheap, it will surely sell out quickly. - 何も準備していないのだから、失敗するに決まっている。 — Since nothing has been prepared, it is bound to fail. - 毎日練習している彼女が上手になるに決まっている。 — She practices every day, so of course she'll improve. - そんな言い方をしたら、相手が怒るに決まっている。 — If you say it like that, the other person is sure to get angry. After reading each sentence, ask what job **に決まっている** is doing. Is it limiting, adding, conceding, asserting, or describing a condition? That habit makes the nuance easier to remember than a single English translation. ## Nuance of に決まっている The key nuance is **express strong certainty based on assumption or attitude**. This matters because N2 grammar often overlaps with easier expressions. The advanced pattern usually adds formality, emphasis, restriction, or a stronger logical relationship. For example: - In formal writing, **に決まっている** often sounds more precise than a casual equivalent. - Compared with **に違いない**, it has a different tone or scope even when the English translation looks similar. ## に決まっている vs に違いない Both **に決まっている** and **に違いない** can express related ideas, but they are different. **に決まっている**: - fits the N2 nuance explained above - often sounds more specific, formal, or emphatic **に違いない**: - is usually broader, simpler, or used in a different register - may be better in casual conversation depending on the sentence Quick contrast examples: - 彼なら合格するに決まっている。 - Try rewriting the sentence with **に違いない** and notice whether the tone or meaning changes. ## Common mistakes with に決まっている Watch out for these mistakes: - Translating it too literally and missing the function in context - Confusing it with **に違いない** just because the English translation overlaps - Using it in casual speech when a simpler pattern would sound more natural A helpful practice method is to write one sentence with **に決まっている**, then compare it with a related grammar point. Explain the difference in your own words. ## Is に決まっている on the JLPT? Yes. **に決まっている** is commonly taught as **JLPT N2** grammar. That means learners should be able to: - recognize it in reading - understand its nuance in context - use it in simple original sentences For test preparation, study the grammar point in full sentences. JLPT questions usually test context, not dictionary translation alone. ## Practice questions for に決まっている Try making your own sentences with these prompts: - Write one sentence that clearly needs **に決まっている**. - Write a second sentence with **に違いない** and compare the nuance. - Find a notice, article, or dialogue where this kind of meaning would be natural. ## Learning path for に決まっている To learn **に決まっている** efficiently, follow a path that matches this pattern's real function. 1. First review the formation so the base structure feels natural. 2. Then compare **に決まっている** with **に違いない** and the related lessons below. These recommendations are chosen from similar semantic or structural families. 3. Finally, write your own sentence where the context makes **に決まっている** necessary. ## Related grammar to review next - [n3 ni chigai nai](/blog/n3-ni-chigai-nai/) — review this next because it is close in meaning, form, or register - [に相違ない](/blog/n2-ni-soui-nai/) — review this next because it is close in meaning, form, or register - [n4 hazu da](/blog/n4-hazu-da/) — review this next because it is close in meaning, form, or register ## Learn に決まっている with Hane If you want to review **に決まっている** together with the related patterns above, Hane helps you connect grammar, kanji, and vocabulary in short, focused sessions. Browse more lessons here: - [All grammar lessons](/blog/) - [JLPT N2 grammar lessons](/blog/n2/)