General term for how much a container, space, or system can hold; also used for data storage, battery charge, and abstract capacity.
このバッテリーの容量は5000mAhです。
This battery has a capacity of 5000mAh.
ハードディスクの容量が足りなくなった。
I'm running out of space on my hard disk.
Physics term; abbreviation of 静電容量 (electrostatic capacitance). Used in technical contexts.
See also: 静電容量
コンデンサの容量を測定する。
Measure the capacitance of the capacitor.
This hard disk has a large capacity.
The file size exceeded the storage capacity.
My phone's storage became full.
I increased the memory capacity.
容量 means capacity or volume, not weight, but its similar sound and kanji ending can make it easy to mix up with 重量.
heat capacity
variable capacity; variable capacitance