How to use も (mo) with numbers in Japanese?

In Japanese there are a few different situations where we use the particle も (transcribed mo) to discuss numbers and quantities, usually to express surprise at a quantity or to express that a number is only approximate.

In this post, we’ll go over how and when to use も (transcribed mo) after a number + a counter, as in １時間 (transcribed jikan, meaning “one hour”) or 千円 (transcribed sen en, meaning “¥1,000”). Along the way, we’ll direct you towards some other resources where you can learn about the use of も (transcribed mo) in other contexts as well.

In Japanese, you’ll often hear も (transcribed mo) used after a number + counter phrase to express that a quantity is larger or smaller than someone expected.

• In an affirmative sentence, you’re expressing surprise that a number is bigger than expected. You might translate this using “as much as…” or “as many as…”

  あの白いTシャツは１０万円もするそうだ。

  Transcription: Ano shiroi tiishatsu wa jūman en mo suru sō da.

  Translation: I’ve heard that that white T-shirt over there costs as much as ¥100,000.

  This price seems amazingly high.

• A negative sentence expresses surprise that the number is smaller than expected. You might translate this using “as little as…” or “as few as…”

  ぼくのこのTシャツは５００円もしなかった。

  Transcription: Boku no kono tiishatsu wa gohyaku en mo shinakatta.

  Translation: This T-shirt of mine didn’t cost me even as little as ¥500.

  This price seems surprisingly low.

This use of も (transcribed mo) is a natural extension of how we use も to express surprise in other contexts, which you can read about in our post on non-parallel uses of も.

When we either don’t know exact numbers or don’t want to present definite numbers, we can set off an approximate number with も (transcribed mo) to indicate that it’s our estimate. In this use, も means something like “or so.”

Notice that the structure here is exactly the same as the structure for expressing surprise at a quantity: Number + Counter + も (transcribed mo). Whether you’re expressing surprise or approximating will depend solely on context! Keep an eye out for words and phrases like “probably,” “I think,” or “if,” which can hint that this is a case where も (transcribed mo) is being used to estimate!

When も (transcribed mo) is used with a number + counter there are two main meanings:

• Expression of surprise that a number is bigger or smaller than expected.

• A way to express that the number is a broad estimate.

The difference is only in the context, they both use the same structure. Check out our numbers with も exercises to practice with this use of も (transcribed mo)!