厚さ and 奥行き: thickness and front-to-back depth
Distinguish a shelf board’s thickness from the shelf’s front-to-back depth. Read the direction of each measurement instead of treating both as the same dimension.
厚さ spans two faces
厚さ, read あつさ, means thickness. 板の厚さを定規で測りました。 says that someone measured the board’s thickness with a ruler.
For a board used in a shelf, thickness is the distance between its two opposing broad faces. This is a different direction from measuring along the board from front to back.
奥行き runs from front to back
奥行き, read おくゆき, can refer to depth extending inward or from front to back. この棚は奥行きが浅く、狭い廊下にも置ける。 says that this shelf is shallow enough to fit even in a narrow hallway.
If the shelf board is 2 centimeters thick and the shelf is 30 centimeters deep, enter different values for 厚さ and 奥行き. Identify the direction being measured rather than memorizing which value is larger.
Physical dimensions and pictorial depth
影を重ねると絵に奥行きが生まれた。 says that adding layers of shadow gave the picture a sense of depth. Here, 奥行き is not a measured front-to-back dimension like that of a shelf.
In a dimension table, distinguish thickness from front-to-back depth. In a description of a picture, context may instead indicate a sense of depth. The word does not always name a ruler measurement.
Does a shelf’s 厚さ of 2 centimeters mean its 奥行き is also 2 centimeters?
Show the answer and why
No. The board’s thickness and the shelf’s front-to-back depth describe different directions. Check 奥行き separately.