one's own weight
Refers to the weight of a person or object itself, often in contexts like bearing one's own weight or collapsing under its own weight.
He worried that the floor might give way under his own weight.
We measure the truck's own weight before calculating the cargo load.
The old bridge collapsed under its own weight.
自重 is the empty (unloaded) weight of a vehicle or structure, whereas 積載量 is the maximum weight it can carry, the opposite concern in engineering specs.
自重（じじゅう, weight) and 自重（じちょう, self-restraint) share identical kanji but are read differently and mean completely different things.
bodyweight training; calisthenics
Compound of 自 (self) and 重 (weight). The technical sense 'unloaded weight' is a specialized extension.