さ and み

This page discusses two adjective nominalizers, さ and み

さ

“-ness” (Measurable)
い Adjectives: drop final い + さ
な Adjectives: No な + さ
いい is once again よい→よさ

さ is a suffix that attaches to adjectives to turn them into nouns. The English equivalent is adding “-ness” to an adjective. This is the most basic and most commonly used one.
It refers to a measurable degree of the adjective in question.

Examples

• 彼の強さにおどろいた
  I was surprised at his strength (How strong he was).
  
  
• よるの静かさ
  The quietness of night.
   
• 日本語の面白さ
  The interestingness (fun-ness) of Japanese.
   
• トマトはちょうどいい赤さだった
  The tomato had the perfect redness

み

“-ness” (State)

(Probably N2 material, but close enough to put here).
み is just like さ, but it describes the state of being an adjective.
While さ works with all adjectives, み only works with a limited number of them.
Typically used with tangible or sense related adjectives. (Tastes, weight, depth, etc).

Tends to come before がある.

Examples

• 重みがあるね
  Its got some weight doesn’t it.
  
  
• このスープは甘みがあるんだ。
  This soup has some sweetness to it.
  
  
• 赤みがあるトマトがいい。
  I want a tomato with some redness.
   
• 痛みがある 
  There is some pain.

み VS さ

For now, you will be fine just using さ and knowing that み exists.

さ – (apparently from さま “appearance”) outward appearance, degree
み – (Apparently from 中身 “insides”) quality of adjective. State of being the adjective. Like 重み (Weight). 

Consider:
深さ – Depth
深み – Depths/deepness
穴の深さ – How deep a hole is.
穴の深み X – Depths of a hole?

彼の強さ – How strong he is
彼の強みは筋肉だ – His strength is his muscles. 

Comparison to Other Forms

• あかい – Red (something)
• あか – Red
• あかく – Redly
• あかさ – how red (degree)
• あかみ – Redness (quality of being red)
• つよい – Strong
• つよく – Strongly
• つよさ – Strength (how strong)
• つよみ – Strongness – State of being strong
• しずかな – Quiet (Something)
• しずか – Quiet (Adjective) (X is quiet) 
• しずかさ – Quietness (degree of quiet).
• しずかみ ✖