Translation guide
In Japanese, 'light blue' is commonly expressed with specific color terms. The most standard word is 水色 (みずいろ), literally 'water color', which refers to a pale, light blue. Another common term is 空色 (そらいろ), 'sky blue', for a bright light blue like the sky. There are also more specific or nuanced terms like 淡青色 (たんせいしょく) for a very pale blue, and ライトブルー, a loanword from English. When describing objects, you can also use 薄い青 (うすいあお) meaning 'pale blue'.
The most common way to say 'light blue' as a color, suitable for everyday conversation.
The standard word for light blue. It evokes the color of water and is widely understood.
彼女は水色のワンピースを着ていた。
She was wearing a light blue dress.
この水色の壁が好きです。
I like this light blue wall.
Literally 'pale blue'. A descriptive phrase that can be used for any light shade of blue.
薄い青のシャツを買いました。
I bought a pale blue shirt.
Loanword from English. Common in fashion, design, and product descriptions.
ライトブルーのジーンズが欲しい。
I want light blue jeans.
Specifically referring to the color of a clear daytime sky.
Means 'sky color'. Used for a bright, clear light blue reminiscent of the sky.
空色の風船が空に浮かんでいた。
A sky-blue balloon was floating in the sky.
For an extremely light, almost white blue.
A formal or technical term for pale blue. Often used in written descriptions or art contexts.
この絵には淡青色が多用されている。
Pale blue is used extensively in this painting.
Means 'extremely pale blue'. A descriptive phrase for very faint blue tints.
ごく薄い青のカーテンを通して光が差し込んだ。
Light streamed through the very pale blue curtains.
水色 (みずいろ) is a general light blue, often with a slightly greenish or watery nuance. 空色 (そらいろ) is specifically the bright blue of a clear sky. In many contexts they are interchangeable, but 空色 implies a brighter, more vivid light blue.
水色の絵の具と空色の絵の具は少し違う。
Light blue paint and sky blue paint are slightly different.
青 by itself means 'blue', not specifically 'light blue'. To specify lightness, use 水色, 薄い青, or add 明るい (あかるい, bright) as in 明るい青 (bright blue).