If you’ve ever wondered how to turn an adjective into a noun in Japanese, one simple and useful tool is ～さ. By adding ～さ to certain adjectives, you can express the degree, quality, or state of that adjective — basically turning “descriptive words” into “things/concepts.”

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1. What Does ～さ Mean?

In English, we often use “-ness” or “-ty” to make adjectives into nouns:

• happy → happiness
• safe → safety
• kind → kindness

In Japanese, ～さ works in a similar way. It changes an i-adjective or certain na-adjectives into a noun.

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2. How to Form Nouns with ～さ

For i-adjectives

1. Remove the final い
2. Add さ

Example:

• 高たかい = high → 高たかさ = height
• 広ひろい = wide/spacious → 広ひろさ = width/spaciousness

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For na-adjectives

1. Remove な
2. Add さ

Example:

• 便利べんりな = convenient → 便利べんりさ = convenience
• 静しずかな = quiet → 静しずかさ = quietness

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📊 Quick Reference Chart

Adjective Type	Example Adjective	Step 1	Step 2	Noun Form	Meaning
i-adjective	高(たか)い	Remove い	Add さ	高(たか)さ	height
	広(ひろ)い	Remove い	Add さ	広(ひろ)さ	spaciousness
na-adjective	便利(べんり)な	Remove な	Add さ	便利(べんり)さ	convenience
	静(しず)かな	Remove な	Add さ	静(しず)かさ	quietness

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3. Example Sentences

・i-adjective examples:

1. 富士山ふじさんの高たかさは日本にほんで一番いちばんです。
   The height of Mt. Fuji is the highest in Japan.
2. この部屋へやの広ひろさが気きに入いっています。
   I like the spaciousness of this room.

・na-adjective examples:

3. 日本にほんの便利べんりさにびっくりしました。
I was surprised by the convenience of Japan.

4. この町まちの静しずかさが好すきです。
   I like the quietness of this town.

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4. Common Adjectives You Can Turn into Nouns

Adjective (Japanese)	Meaning	Noun Form	Meaning
高(たか)い	high, tall	高(たか)さ	height
広(ひろ)い	wide, spacious	広(ひろ)さ	width, spaciousness
長(なが)い	long	長(なが)さ	length
明(あか)るい	bright	明(あか)るさ	brightness
新(あたら)しい	new	新(あたら)しさ	newness
静(しず)かな	quiet	静(しず)かさ	quietness
便利(べんり)な	convenient	便利(べんり)さ	convenience
大切(たいせつ)な	important	大切(たいせつ)さ	importance

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5. When NOT to Use ～さ

Not every adjective can be turned into a noun with ～さ naturally. For feelings or states that are more subjective, Japanese often uses ～み instead (e.g., 悲しみ “sadness”).

• ～さ = measurable, objective qualities
• ～み = subjective feelings, impressions

Example:

• 高たかさ (objective: measurable height)
• 悲かなしみ (subjective: emotional sadness)

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6. Quick Practice

Turn the following adjectives into noun forms with ～さ:

1. 高い (たかい)
2. 明るい (あかるい)
3. 静かな (しずかな)
4. 大切な (たいせつな)

(Answers: 高さ, 明るさ, 静かさ, 大切さ)

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Key Takeaway:
Using ～さ is an easy and powerful way to talk about qualities or characteristics as “things” in Japanese. Once you learn it, you’ll start noticing it everywhere — in signs, news, conversations, and even advertisements.

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