ても構わない / てもかまわない【てもかまわない / てもかまわない】

ても構わない says something is acceptable, or that the speaker doesn't mind it: "it's all right if ~", "I don't mind if ~". A verb takes も構わない after its て-form, an い-adjective becomes くても構わない, and a noun or な-adjective takes でも構わない.

かまわない構わない is the negative of かまう構う, "to mind", so the whole is literally "even if ~, I don't mind". It is just as often written in kana, かまわない. The polite form is かまいません構いません.

• × 高いでも構わない → 高くても構わない

ても構わない or てもいい

Both give permission. ても構わない is a step more formal, and it says the speaker has no objection rather than that the thing is good. That makes it the choice at work and in service settings, and for accepting a drawback.

Asking with 構いませんか

構いませんか asks "would it be all right if ~?". It is literally "you don't mind?", so the reply that grants it agrees and starts with はい or ええ, where English "Do you mind?" gets "no".

Not caring how it turns out

With a question word, or about something that could go badly, ても構わない says the outcome makes no difference to the speaker.

Usage notes

These go beyond giving permission.

なくても構わない

The negative becomes なくても構わない: "it's all right not to ~", close to なくてもいい.

A noun or な-adjective takes でなくても構わない.

Offering

About your own action, ても構わない offers to do it.