# The differences between 速さ, 早さ,　and 速度

I was emailing a friend and used the phrase "タイピングすることの早さ" which I discovered was very incorrect. I did some searching on Google and here is what I discovered:

• タイピングの速度　<-rare
• タイピング速度 <-common
• タイピングの速さ　<-common

I'm curious as to what the differences between 速さ, 早さ,　and 速度　are. Also, why is の used more commonly with 速さ and not 速度?

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What made you think タイピングの速度 is rare? I got 401,000 google hits with タイピングの速度, while 83,500 with タイピング速度. – user1016 May 9 '13 at 8:11
Oh yeah, you're right. I just glanced at the first few results and counted. After searching again (and using quotation marks for exact phrases) I get 395,000, 82,400, 24,700 and 480,000 respectively. – user2052561 May 9 '13 at 10:07
Here's what my Japanese friend told me: In a daily conversation, people might think that 速さ is just a speed itself and 速度 shows more specifically the degree of how fast the speed is. Actually, this difference is commonly discussed in physics or math class. Using an idea of vectors in mathematics, 速さ is explained as a vector (its orientation + the magnitude of the vector) and 速度 is the magnitude of the speed. As for the typing speed, タイピングの速さ is commonly used as Google showed you. – user2052561 May 9 '13 at 10:20

The nouns 早さ and 速さ are derived from the adjectival verbs 早い and 速い, which both can mean both "fast" and "early". Being derived from adjectival verbs, they are native Japanese words.

On the other hand, 速度 is a Chinese-derived word, which means "speed" or "rate" (and doesn't mean "earliness").

The kanji 早 is usually used for the sense of "early" and 速 usually for speed, although these concepts overlap a little. (E.g. 早いですね doesn't need to be "you are early", it could be "wow, you were fast" in the sense of "you got here earlier than I expected".)

For the question about typing speed, you can interpret タイピング to have the status of a Chinese-derived word in the following sense:

Chinese-derived nouns (which are usually two-characters long) can form compound nouns simply by concatenation (without a joining particle like の). E.g. 自宅教育 "home-schooling" from 自宅 "home" and 教育 "education".

On the other hand, Japanese-derived nouns are usually connected to other nouns with の.

Thus we get

○ タイピング速度
× タイピングの速度
× タイピング速さ
○ タイピングの速さ

Here ○ and × indicate what sounds most natural in the sense of the above explanation. Of course, you can always combine two nouns with の, so タイピングの速度 is grammatically correct as well.

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Excellent explanation! – user2052561 May 9 '13 at 3:17
「タイピングの速度」もOKです^^ – user1016 May 9 '13 at 7:29

I don't think タイピングすることの早さ is incorrect; it just sounds very strange, like "the speed of the act of typing" in English.

I think the の is more commonly left out when dealing with 熟語, while it's more, if not completely necessary when using 単語.

• タイピングの速度　→　"The speed of typing" (correct, but sounds a little stiff)
• タイピング速度　→　"Typing speed"
• タイピング速さ　→　Sounds incorrect; possibly ungrammatical
• タイピングの速さ　→　Again, "The speed of typing", but rolls off the tongue smoother than the first one, so maybe that's why it's more common.
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「タイピングの速度」のほうが「タイピング速度」より、書き言葉よりも話し言葉でよく使い、硬くないと思います。たとえば題名には「タイピング速度計測/向上」とかでも、‌​カジュアルな本文には「タイピングの速度を計る/上げたい・・・」とか。 – user1016 May 9 '13 at 7:36