Pedantically, the PC DOS 3 1/2" HD format is 1440 * 1024 bytes[1], so either 1.47456 MB (SI) or 1.40625 MiB (IEC), though "1.44 MB" was the official IBM designation for the format.

[1] 2 sides / disk * 18 tracks / side * 80 sectors / track * 512 bytes / sector = 1,474,560 bytes = 1440 * 1024 bytes