～さ
nominalizer of degree
～さ turns an adjective into a noun that names its degree or extent. Take an い-adjective, drop the final い, and add さ; for な-adjectives, add さ directly to the stem.
In English this matches noun pairs like “high → height”, “long → length”, or “kind → kindness”. Once an adjective becomes a ～さ noun, you can measure it, compare it, or make it the topic of a sentence.
1. Measurable degree
The most common use is with adjectives of size and amount, where ～さ names the quality as something you can measure with numbers.
この山の高さは三千メートルです。
“This mountain's height is three thousand meters.”
- この = this
- 山（やま）= mountain
- の = possessive particle (“'s”)
- 高さ（たかさ）= height
- は = topic marker
- 三千（さんぜん）= three thousand
- メートル = meters
- です = is (polite)
2. Talking about a quality itself
～さ also works with qualities you cannot measure with a ruler. It lets you talk about the quality as a thing in its own right.
北海道の冬の寒さは有名です。
“The cold of Hokkaido's winters is famous.”
- 北海道（ほっかいどう）= Hokkaido
- の = possessive particle (“'s”)
- 冬（ふゆ）= winter
- 寒さ（さむさ）= cold, coldness
- は = topic marker
- 有名（ゆうめい）= famous
- です = is (polite)
How to form it
い-adjective minus い + さ, or な-adjective stem + さ
- 高い（たかい）= high → 高さ（たかさ）= height
- 長い（ながい）= long → 長さ（ながさ）= length
- 便利（べんり）= convenient → 便利さ（べんりさ）= convenience
Key idea
～さ turns a quality into a measurable noun. It converts “high” into “height”, a noun you can measure, compare, and talk about.
Other N4 grammar
Updated .