sd_storage Data Size Converter (Bit, Byte, KB, MB, GB, TB) star

How It Works

Enter a value, pick the unit you're converting from, pick the unit you want, and the result updates instantly. The tool covers the full ladder from a single bit up to petabytes: bit, byte, KB, MB, GB, TB, PB. The important choice is the mode switch above the fields — Binary (1024) or Decimal (1000) — because "kilobyte" has quietly meant two different things for decades, and picking the wrong one is the single most common reason a converted number looks "wrong."

In binary mode, each step is a multiplication by 1,024 (2¹⁰): 1 KiB = 1,024 bytes, 1 MiB = 1,024 KiB, 1 GiB = 1,024 MiB, and so on — this is how operating systems, RAM and most file managers actually report size, because computer memory is naturally organized in powers of two. In decimal mode, each step is a clean multiplication by 1,000: 1 kB = 1,000 bytes, 1 MB = 1,000,000 bytes, 1 GB = 1,000,000,000 bytes — the SI convention that hard drive and SSD manufacturers use on their packaging and spec sheets, because it is simpler to reason about and matches how every other metric unit scales. All the arithmetic runs as ordinary JavaScript numbers (not BigInt) — a standard double-precision float is exact for whole numbers up to 2⁵³, which comfortably covers petabyte-scale values without any precision loss.

Good to Know

This binary-vs-decimal split is not a modern quirk — it was formalized by the IEC 60027-2 standard in 1998, which introduced the prefixes kibi-, mebi-, gibi-, tebi- (and the units KiB, MiB, GiB, TiB) specifically to distinguish power-of-two values from the SI decimal kilo-, mega-, giga- prefixes that had already meant "exactly 1,000" everywhere else in science and engineering for over a century. Before that standard existed, "kilobyte" was used loosely for both meanings depending on context, which is exactly the ambiguity IEC 60027-2 was created to end — even though, in casual use, "KB/MB/GB" still gets used to mean either one today.

This is precisely why a brand-new drive labeled 1 TB shows up in your operating system as roughly 931.32 GiB (or "931 GB" in an OS that mislabels binary units with decimal names). The manufacturer sold you 1,000,000,000,000 bytes using the decimal definition — that part is accurate and matches the box. Your OS, however, reports free space in binary units: dividing that same byte count by 1,024³ instead of 1,000³ yields the smaller-looking 931.32 figure. No storage capacity actually went missing; the same physical bytes are simply being counted in two different unit systems, and the "used" space taken by the filesystem itself and pre-installed system files accounts for a small additional gap on top of that.