Data Storage Converter
Convert between bits, bytes, decimal (KB/MB/GB/TB) and binary (KiB/MiB/GiB/TiB) sizes — each option is labeled with exactly which family it belongs to, because the two are genuinely different numbers, not a rounding choice.
Every unit at once
Grouped by family — decimal (SI) and binary (IEC) are never mixed in the same column.
Base units
| Bits (bit) | — |
| Bytes (B) | — |
Decimal (SI, base-1000)
| KB — decimal (10³ B) | — |
| MB — decimal (10⁶ B) | — |
| GB — decimal (10⁹ B) | — |
| TB — decimal (10¹² B) | — |
Binary (IEC, base-1024)
| KiB — binary (2¹⁰ B) | — |
| MiB — binary (2²⁰ B) | — |
| GiB — binary (2³⁰ B) | — |
| TiB — binary (2⁴⁰ B) | — |
Two prefix families, and why they don't agree
"Kilo-", "mega-", "giga-", and "tera-" have one technically correct meaning: powers of 1000, the same as everywhere else in the metric system. That's the decimal (SI) family — 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, and so on — and it's what's printed on every hard drive and SSD box. But computers address memory and storage in binary, where the natural "round number" is a power of two, so a second family grew up alongside it: the binary (IEC) prefixes KiB, MiB, GiB, and TiB, each exactly 1,024× the one below. For decades, operating systems — Windows File Explorer chief among them — calculated storage the binary way but kept printing the decimal symbol "GB" on screen, which is precisely why a drive that's honestly, fully 1TB by the manufacturer's correct decimal definition reads as a smaller-looking "931 GB" once Windows divides those same bytes by 1024 three times. This tool keeps both families clearly labeled everywhere, including in the dropdown itself, so you always know which math you're getting.
Worked example — the "1TB drive" phenomenon
A drive box says 1 TB, decimal: exactly 10¹² = 1,000,000,000,000 bytes. Convert that same byte count into GiB (binary, what Windows actually computes) by dividing by 2³⁰ = 1,073,741,824, and you get ≈ 931.32 GiB — the exact number behind the "why is my 1TB drive showing 931GB" question. Nothing on the drive is missing; 10¹² bytes is still 10¹² bytes. It's only smaller-looking because it's being measured with a binary ruler and printed with a decimal label. Meanwhile the binary family is internally exact too: 1 GiB = 1,024 MiB = 1,073,741,824 bytes, with no rounding anywhere in that chain.
Frequently asked questions
Why does my new "1TB" drive show up as only 931GB in Windows?
Because two different, equally legitimate definitions of "GB" are colliding. Drive manufacturers label capacity using the decimal (SI) definition — 1 TB = 10¹² = 1,000,000,000,000 bytes, the technically correct meaning of the metric prefix "tera-". But Windows File Explorer calculates and displays free space using binary math (dividing by 1024 three times to get from bytes to what it calls "GB"), while still showing the decimal symbol "GB" instead of the correct binary symbol "GiB". Run the numbers and 10¹² bytes ÷ 1024³ ≈ 931.32 — so a drive that is genuinely, fully 1TB by its manufacturer's (correct) definition reads as "931 GB" in a tool that's silently doing binary math under a decimal label. Nothing is missing from the drive; it's a unit-labeling mismatch, not a shortfall.
So which one is "right" — decimal or binary?
Both are right, for different jobs — they're just not interchangeable, and the mistake is using one number with the other's label. Decimal (KB/MB/GB/TB, powers of 1000) is the actual SI standard for the prefixes kilo-, mega-, giga-, tera-, and it's what storage manufacturers, network speeds, and most non-Microsoft software use. Binary (KiB/MiB/GiB/TiB, powers of 1024) reflects how memory and file systems actually address storage internally in power-of-two blocks, and it's what Windows historically displays (mislabeled) and what RAM capacity has always effectively meant. Neither is a rounding error of the other — 1 GB and 1 GiB are two genuinely different byte counts (1,000,000,000 vs. 1,073,741,824), about a 7.4% gap that grows at every larger prefix.
Why include bits as an option? I only ever see bytes.
Because network and internet speeds are almost always quoted in bits per second, not bytes — a "100 Mbps" connection is 100 million bits per second, and since 1 byte = 8 bits, that's 100 ÷ 8 = 12.5 megabytes per second of actual download throughput. It's one of the most common storage/networking mix-ups: people expect a "100 Mbps" plan to download at 100 MB/s and are confused when a file manager reports roughly an eighth of that speed. This tool includes bits precisely so you can convert an advertised connection speed into the byte-based number your download progress bar will actually show.
Is 1 GiB really equal to 1024 MiB, exactly?
Yes, exactly, by definition — that's the entire point of the binary (IEC) prefixes: each step up is precisely 2¹⁰ = 1024 of the step below, with no rounding anywhere. 1 GiB = 1024 MiB = 1024 × 1024 KiB = 1,073,741,824 bytes, all exact integers. Compare that to the decimal family, where 1 GB = 1000 MB = 1,000,000,000 bytes exactly as well — both families are internally exact, they just don't line up with each other because 1000 ≠ 1024.
Is my data or input sent anywhere?
No. Every conversion is plain multiplication and division done in your browser the instant you type — nothing you enter is transmitted, logged, or stored on a server.