Usable capacity — gross, net and the gap between them
Usable capacity is the portion of a battery's total energy the car will actually let you use; the remainder is a buffer reserved to protect the cells.
Manufacturers quote capacity in two ways. Gross is everything the cells physically hold. Net, or usable, is what remains after the buffer at the top and bottom that the management system keeps off limits. Range is calculated from the net figure; marketing frequently uses the gross one.
Why it matters when buying
The size of the buffer is a design decision, not a constant, and it varies between manufacturers by more than most buyers expect. A car quoting a larger battery can offer less usable energy than a rival quoting a smaller one. When comparing two models the net figure is the only one worth comparing, and where a manufacturer publishes only the gross figure that omission is itself informative.
Buffers also differ by chemistry. LFP packs tolerate a full charge, so their usable share tends to be higher and the manufacturer will tell you to charge to capacity. Nickel packs keep more in reserve. This is why consumption per kilometre, which is independent of pack size, is often the more honest basis for comparing two cars than range.
Every specification block on this site records the net figure where the manufacturer publishes it, and says so plainly where it does not.
Updated Aug 21, 2026