const units = {
  B: 1,

  kB: 1000 ** 1,
  KiB: 1024 ** 1,

  MB: 1000 ** 2,
  MiB: 1024 ** 2,

  GB: 1000 ** 3,
  GiB: 1024 ** 3,

  TB: 1000 ** 4,
  TiB: 1024 ** 4,

  PB: 1000 ** 5,
  PiB: 1024 ** 5,
} as const;

type Unit = keyof typeof units;

function convert(value: number, from: Unit, to: Unit): number {
  return value * units[from] / units[to];
}

if (import.meta.main) {
  console.log(convert(1, "MiB", "kB"));
}