sum of three dimensions; total of length, width, and height
Used primarily in shipping and logistics contexts to describe the combined measurement of a package's three sides.
This package exceeds 160 cm in total dimensions, so an additional fee applies.
The courier service handles packages with a total dimension sum of up to 170 cm.
サイズ is a general term for size, while 三辺合計 specifically refers to the sum of three dimensions (length + width + height) in shipping contexts.
容積 means volume (capacity), whereas 三辺合計 is a linear sum of dimensions, not a volumetric measure.
Compound of 三辺 (three sides) and 合計 (total sum). The reading さんぺん follows standard rendaku for 三 (さん) + 辺 (へん).