Byte Size Converter

Type a number of bytes (or KB, MB, GB, etc.) and read the conversions across every common scale. Both decimal (kB = 1000) and binary (KiB = 1024) prefixes show, so you can see which one a vendor is quoting when their numbers don't match yours.

Drive manufacturers report decimal capacity. Operating systems report binary. The 12% gap between the two is why a 1 TB drive shows up as 931 GiB in your file manager — both are correct, just measured differently.

Run a quick conversion before sizing buckets, calculating bandwidth bills, or sanity-checking a backup that "finished too fast."

The split is decimal vs binary prefixes. Decimal: kB = 1,000 B; MB = 1,000,000 B; GB = 10^9 B; TB = 10^12 B. Binary: KiB = 1,024 B; MiB = 1,048,576 B; GiB = 2^30 B; TiB = 2^40 B. The IEC standardized the binary prefixes (kibi, mebi, gibi, tebi) in 1998 to fix the long-standing ambiguity. Most operating systems, hard drive vendors, and networking standards have settled into different camps and refuse to budge. The tool shows both columns simultaneously and labels them so you stop wondering which one applies.

Worked example. A drive labeled 2 TB (decimal: 2,000,000,000,000 B) shows up in your file manager as 1.819 TiB (2 · 10^12 / 2^40 = 1.819). The 9% gap between TB and TiB is structural, not deceptive — both numbers describe the same physical drive, just with different conversion factors. The marketing number is bigger; the OS number is what you actually have to work with when filling the disk. SSDs report capacity the same way; the gap doesn't go away.

The big gotcha is networking. Network speeds are quoted in megabits per second (Mb/s), not megabytes per second (MB/s). 8 Mb/s = 1 MB/s. A 100 Mb/s connection's theoretical maximum download speed is 12.5 MB/s — and typical real-world throughput is around 11.5 MB/s after framing overhead. People confuse the two constantly and get angry their gigabit fiber "only" runs at 125 MB/s. That's correct. Same prefix conventions for the bits side: 1 Gbit = 10^9 bits in standard usage, no binary version.

A practical opinion: when ordering storage for production (cloud buckets, drives, backups), size in GiB or TiB and provision accordingly. A "1 TB allocation" in cloud billing is usually 1,000 decimal GB, but your application's full-disk-detection code might be checking against a binary threshold. Pick one convention internally, document it, and stop arguing with hardware that uses the other. Linux's df -h defaults to binary (with the dual-meaning K/M/G suffixes); df -H forces decimal.