てもいい — May, It's Ok To

Meaning & Usage

てもいい expresses permission or acceptability — translated as "may," "it's okay to," or "you can" in English. You'll hear it constantly in Japan: in classrooms, shops, on trains, and in everyday small talk.

It covers two situations. First, giving permission: てもいいです tells someone "you may do X." A teacher letting a student leave early, a parent okaying dessert — both use this pattern. Second, asking for permission: add か to form てもいいですか ("May I...?" / "Is it okay if I...?"). This question form comes up within the first hour of any trip to Japan.

てもいいです is the default polite form — right for teachers, shop staff, or anyone you've just met. Drop the です with friends: てもいい (or てもいい? with rising intonation) fits casual settings naturally. For business meetings or formal written contexts, てもよろしいでしょうか is the ultra-polite equivalent.

The particle も means "even" or "even if," so てもいい literally reads as "even if you do X, it's fine." That slight connotation of generosity — "I'm okay with it even so" — is worth noting. It also surfaces in more complex constructions at higher levels.

Structure & Formation

Formation depends on the word type. The adjective rules differ from verbs — and the difference between them comes up regularly on the N5 exam.

Add です for the polite form: てもいいです. Add か to ask for permission: てもいいですか. Tack on よ when granting permission warmly — てもいいですよ has a friendly "go right ahead" feel.

Note: よい can replace いい in formal or written Japanese. In everyday speech, いい is standard.

Example Sentences

Asking for Permission (～てもいいですか)

Giving Permission (～てもいいです)

Casual Permission Among Friends (～てもいい)

With Adjectives and Nouns

Common Mistakes

Mistake 1: Using the Dictionary Form Instead of the て-form

❌ 食たべるもいいですか。

✅ 食たべてもいいですか。

もいい attaches to the て-form only — not the dictionary form. 食たべる → 食たべてもいい, 行いく → 行いってもいい, 飲のむ → 飲のんでもいい. If て-form conjugation isn't automatic yet, practice it separately — てもいい depends on it.

Mistake 2: Omitting the Particle も

❌ ここで食たべていいですか。

✅ ここで食たべてもいいですか。

ていい does appear in very casual speech, but the standard form is てもいい. Without も, you lose the "even if" nuance — and in formal contexts or on the exam, it sounds incomplete. Always include も.

Mistake 3: Incorrect い-adjective Conjugation

❌ 大おおきいでもいいです。

✅ 大おおきくてもいいです。

い-adjectives need an extra step: drop the final い, add くて, then attach もいい. 大おおきい → 大おおきくてもいい, 小ちいさい → 小ちいさくてもいい, 安やすい → 安やすくてもいい. でもいい is for nouns and な-adjectives only — never い-adjectives.

Mistake 4: Confusing てもいいです with てはいけません

❌ (Using てもいいですか when you want to express that something is prohibited)

✅ Use てはいけません or てはだめです to express prohibition.

てもいいです grants permission. てはいけません prohibits. They're exact opposites. If someone asks てもいいですか and the answer is no, respond with いいえ、～てはいけません or simply いいえ、だめです.

Mistake 5: Overusing Polite Forms in Casual Conversation

❌ (To a close friend) 食たべてもいいですか。(sounds too formal and stiff)

✅ 食たべてもいい？ (natural and casual among friends)

てもいいですか is grammatically fine anywhere, but with close friends it can sound stiff — sometimes even sarcastic. Drop the です and ask てもいい? instead. This register shift is one of the small things that separates textbook Japanese from how people actually talk.

Cultural Notes

Asking permission is second nature in Japan. てもいいですか comes up everywhere — restaurants, classrooms, trains, temple grounds. When visitors take the time to ask before photographing or borrowing something, it tends to be noticed and appreciated.

A few natural ways to respond when someone asks てもいいですか: はい、どうぞ (go ahead) or いいですよ (that's fine) to say yes; どうぞ、でも～してください (go ahead, but please...) if there's a condition. For a soft refusal, Japanese speakers often leave the sentence unfinished: すみません、ちょっと… ("I'm sorry, that's a little...") is widely understood as a polite no. More directly: ちょっと困こまります (that would be a bit of a problem).

Asking rather than assuming reflects a core Japanese social value: awareness of shared space and consideration for others. Knowing てもいいですか isn't just useful Japanese — it signals that you understand how the language and the culture fit together.

Related Grammar Points

• てください — Please Do (Grammar N5)
• ている — Progressive and Resultant State (Grammar N5)
• あげる — To Give (Giving to Others) (Grammar N5)
• くれる — To Give (To Me) (Grammar N5)
• ないでください — Please Don't (Grammar N5)
• と思う — I Think That (Grammar N5)

JLPT Tips

てもいいです is a core N5 grammar pattern and will very likely appear on the exam. Know it from both sides: granting permission and asking for it.

On the grammar section, expect three question types: verb form (て-form vs. dictionary form); adjective ending (くてもいい for い-adjectives vs. でもいい for な-adjectives and nouns); and selecting the right expression for a short dialogue or situation.

The てもいいです vs. てはいけません contrast is a reliable exam trap — they appear as opposing answer choices. Context tells you which: rules, signs, or corrections → てはいけません. Permission granted or a polite request → てもいいです.

For い-adjectives, the connector is always くて, never で. Drill a few examples until the pattern feels automatic: 寒さむい → 寒さむくてもいい, 高たかい → 高たかくてもいい, 難むずかしい → 難むずかしくてもいい. When it's second nature, the wrong options won't trip you up.