Photo and Video File Size, Explained

Compression and bit depth can dominate.

Two files with the same pixel dimensions can differ because of codec, quality, scene complexity, metadata, and bit depth. Use a measured sample when possible.

Bitrate is the direct planning input.

Multiply megabits per second by seconds, divide by eight for megabytes, then convert units. Variable-bitrate recordings need an observed average or a stated range.

Drive labels and operating systems may display different numbers.

Manufacturers generally quote decimal GB, while software may use binary GiB or label binary values as GB. The underlying bytes have not disappeared.

Capture size affects cards, editing, upload, and backup.

Use the same source assumption in storage and transfer tools so the plan remains consistent. Keep extra copies and working headroom separate.