The mass of the material inside a capsule, excluding the capsule shell.
Also called: fill mass; net fill weight; capsule filling weight; weight variation.
Net fill weight and shell tare
Net fill weight is gross filled-capsule weight minus shell mass. Using the same capsule’s before-and-after weights accounts for its own shell contribution. Subtracting a batch-average tare instead estimates that contribution, because individual shell weights can vary.
Net fill mass = gross filled-capsule mass − shell mass
Can the average fill weight be right while individual fills vary?
Yes. An average summarises the group and does not show the individual spread or a changing pattern over time. A mean close to target cannot alone describe how consistently the individual capsules were filled.
Identify whether a reported value is an individual result, an average or a measure of variation, and whether it is net or gross. These records answer different questions about filling performance.
No. A volume-and-density calculation estimates what might fit; fill-weight data describe material actually in the capsule. The two claims should not be merged. Likewise, a named weight-control feature needs its stated measurement basis and scope rather than an assumption that all fillers measure every capsule’s net weight.
A fill-weight specification should state the target and unit, tare basis, and how individual results and variation will be reported.