N4 Adjective Transformations

[Adjective]+さ: meaning, usage and examples

[Adjective]+さ means: an Adjective to turn it into a Noun.

Updated 9 November 2026 · By the My Senpai team · Spotted a mistake? Tell us

Examples

1. この川かわの深ふかさはどのくらいですか。

   How deep is this river?

2. 部屋へやの広ひろさを測はかりました。

   I measured the size of the room.

3. 日本にほんの夏なつの暑あつさに驚おどろきました。

   I was surprised by the heat of summer in Japan.

4. このかばんは、大おおきさがちょうどいいです。

   This bag is just the right size.

When to use it

Turns an adjective into a noun that names the quality or its degree: 高たかい 'high' → 高たかさ 'height', 重おもい 'heavy' → 重おもさ 'weight', 便利べんり 'convenient' → 便利べんりさ 'convenience'. Use it to measure or ask about size and amount (長ながさは何なんメートルですか) and to talk about a quality as a thing (日本にほんの夏なつの暑あつさ).

Nuance

Neutral, used in speech and writing, and it works with most adjectives. いい becomes よさ. Measurement words such as 長ながさ, 高たかさ, 重おもさ, 大おおきさ and 深ふかさ are the most common and appear on signs, forms and tests.

Compare

Compare the adjective itself: この川かわは深ふかいです describes the river, この川かわの深ふかさ names its depth so you can ask about it or measure it. Compare み (甘あまみ, 痛いたみ, 楽たのしみ): it also makes nouns, but only from some adjectives, and names a feeling or flavor rather than a degree.

Tip: To ask 'how big' or 'how long', use the さ noun with どのくらい: 長ながさはどのくらいですか (how long is it?).