Translation guide
The English word 'thickness' refers to the dimension of an object from one surface to the opposite, or the quality of being thick. In Japanese, the most common equivalent is 厚さ (atsusa), but the appropriate word depends on what is being described: flat objects, cylindrical objects, liquids, or abstract density.
Describing the dimension between two parallel surfaces of a flat object.
The standard word for thickness of flat things like boards, walls, books, or slices. It is a noun derived from the adjective 厚い (atsui, 'thick').
The thickness of this board is 2 centimeters.
Please measure the thickness of the wall.
Similar to 厚さ, but often implies a sense of substantial thickness or volume, and can be used more subjectively. Common in everyday speech.
This steak looks delicious with its thickness.
Describing the girth or diameter of something round or thick in a non-flat way.
Used for thickness in the sense of girth or diameter, such as for ropes, tree trunks, arms, or columns. Derived from 太い (futoi, 'thick/fat').
Is the thickness of this rope sufficient?
I was surprised at the thickness of his arms.
Describing how thick a liquid or semi-liquid substance is, like soup, paint, or fog.
Used for concentration or thickness of liquids, gases, or colors. Derived from 濃い (koi, 'thick/dense/strong').
Please adjust the thickness of the soup.
I couldn't see ahead because of the thickness of the fog.
Specifically refers to a desirable, smooth thickness or viscosity, often in cooking (like a thickened sauce).
Describing non-physical thickness, such as of a book's content, atmosphere, or voice.
厚さ (atsusa) is for flat objects like paper or boards. 太さ (futosa) is for cylindrical or rope-like objects. 濃さ (kosa) is for liquids, gases, or colors. Using the wrong one can sound unnatural.
thickness of a book
thickness of a tree
thickness (strength) of coffee
For human body parts, 'thickness' often translates to 太さ (futosa) for limbs, but for 'thick' as an adjective, 太い (futoi) is more common. Saying 厚い腕 (atsui ude) would mean a flat, board-like arm, which is incorrect.
このソースはちょうど良いとろみだ。
This sauce has just the right thickness.
I like the thickness (richness) of this paint.