Bitrate—not resolution alone—drives data use
Two 1080p cameras can produce very different data volumes because frame rate, codec, motion in the scene, quality target, and variable-bitrate limits differ. Use the configured average bitrate or a measured transfer rate whenever possible. Manufacturer resolution labels are not enough for storage planning, and peak bitrate still matters when assessing whether an upload connection can remain stable.
Understand what the calculator includes
At a constant 1 megabit per second, one hour of video is approximately 0.45 gigabytes in decimal units. The calculator multiplies that rate by active hours, camera count, and days. It does not add audio, transport overhead, file-system reserve, mirroring, thumbnails, database indexes, or provider-side copies. Add margin rather than buying exactly the displayed capacity.
Measure a representative day before final purchase
A quiet indoor test underestimates a tree-filled outdoor scene, busy road, snowfall, rain, or night noise because those conditions are harder to compress. Record a representative day using the intended codec and quality settings, then compare actual file size with the estimate. Also verify that the network has spare upload capacity for other household or business traffic.