JLPT N1Spoken and writtenMatter-of-fact

ともなると・ともなれば・にもなるとonce you get as far as

At a certain level things are naturally different: once you are a department manager, once you are fifty, once it is December. The word before it is a step up some scale. People say it and write it.

部ぶ長ちょうともなると、部ぶ下かの失しっ敗ぱいにも責せき任にんを負おわなければならない。

Once you get to be a department manager, you have to answer for your staff's mistakes as well.

五ご十じゅっ歳さいにもなると、健けん康こう診しん断だんの数すう値ちが以い前ぜんより気きになってくる。

By the time you get to fifty, your check-up results start to weigh on you more than they used to.

十じゅう二に月がつともなれば、朝あさ晩ばんはかなり冷ひえ込こむ。

Once it gets to December, the mornings and evenings turn really cold.

How to form it

Noun + ともなると／ともなれば

The two mean the same. Before a big undertaking, a verb in the dictionary form: 家いえを建たてるともなると.

The plainer form

Noun + に（も）なると

Built on になる, and common after an age or a number. With も it says the same as ともなると. Without it, it is just "when it gets to".

Before it: A rank (社しゃ長ちょう, プロ), an age (四よん十じゅっ歳さい, 高こう校こう生せい), a time (十じゅう二に月がつ, 夜よ中なか), a stage or a size (決けっ勝しょう, 百ひゃく人にん).
After it: What is naturally so at that level. Not a request, and not your own plan.
Tone: Matter-of-fact: "as you'd expect by then".
Where you'll meet it: Conversation, essays, commentary.

ともなると or となると?

One も apart from となると. That も is the "as far as": a level reached, not just a case.

彼かれが社しゃ長ちょうとなると、反はん対たいする人ひとも出でてくるだろう。

If he does become president, some people will probably object.

One real case, and what it will bring.

社しゃ長ちょうともなると、自じ由ゆうな時じ間かんはほとんどない。

Once you get to be president, you have hardly any time to yourself.

Any president. At that level, this is how it is.

となるとN2

"If it actually comes to that": it is decided, or really in front of you, and you turn to what it will take.

いざ自じ分ぶんでやるとなると、なかなか難むずかしい。

When it comes to actually doing it yourself, it's pretty hard.

In use

代だい表ひょうチームの監かん督とくともなると、一ひとつ一ひとつの決けつ断だんが大おおきく報ほう道どうされる。

Once you are coach of the national team, every single decision is big news.

全ぜん国こく大たい会かいの決けっ勝しょうともなると、わずかな判はん断だんの遅おくれが勝しょう敗はいを分わける。

When it gets as far as the final of a national tournament, the slightest hesitation decides the match.

家いえを一いちから建たてるともなれば、費ひ用ようだけでなく完かん成せいまでの時じ間かんも考かんがえなければならない。

With something as big as building a house from scratch, you have to think not only about the cost but about how long it will take.

It says how things are

What follows is true of anyone at that level. To tell one person what to do, it is なんだから.

Not said: 高こう校こう生せいともなると、自じ分ぶんで起おきなさい。

(You're in high school now, so get yourself up.)

もう高こう校こう生せいなんだから、自じ分ぶんで起おきなさい.

Check yourself

1Which one fits?

田た中なかさんが来こない（　　）、席せきが一ひとつ余あまりますね。

Choose an answer to see why.

2Which sentence sounds natural?

Choose an answer to see why.

More sentences

博はく士し課か程ていの最さい終しゅう年ねんともなれば、研けん究きゅう成せい果かを論ろん文ぶんとしてまとめる力ちからが求もとめられる。

By the final year of a doctorate, you are expected to be able to write your findings up as a thesis.

参さん加か者しゃが百ひゃく人にん規き模ぼにもなると、会かい場じょうの安あん全ぜん管かん理りにも専せん門もんのスタッフが必ひつ要ようだ。

Once an event gets to around a hundred people, you need trained staff for safety at the venue as well.

海かい外がいに新あたらしい工こう場じょうを建たてるともなれば、現げん地ちの法ほう律りつを詳くわしく調しらべる必ひつ要ようがある。

With something as big as building a new factory abroad, the local law has to be looked into in detail.