Data Storage Converter
Bits and bytes through petabytes, in both decimal (GB) and binary (GiB) — side by side, never mixed.
Last updated
Your details
Result
- Bytes
- 1,000,000,000
- Kilobytes (KB)
- 1,000,000.0000
- Megabytes (MB)
- 1,000.0000
- Gigabytes (GB)
- 1.000000
- Terabytes (TB)
- 0.00100000
- Kibibytes (KiB)
- 976,562.5000
- Mebibytes (MiB)
- 953.6743
- Gibibytes (GiB)
- 0.931323
- Tebibytes (TiB)
- 0.00090949
- Bits
- 8,000,000,000
1 KB = 1,000 bytes
1 KiB = 1,024 bytes — what an operating system counts
Often displayed as "GB" by Windows
1 gigabyte…
Decimal steps by 1,000. Binary steps by 1,024.
1,000,000,000 bytes in total
÷ 1,000³ = 1.000000 GB
÷ 1,024³ = 0.931323 GiB
1,000,000,000
Formula — written step by step
A drive sold as 1 TB…
Decimal steps by 1,000. Binary steps by 1,024.
1 TB = 1,000⁴ = 1,000,000,000,000 bytes
1 GiB = 1,024³ = 1,073,741,824 bytes
1,000,000,000,000 ÷ 1,073,741,824
931.32 GiB
The drive holds exactly what the box says. The file manager divides by 1,024 three times and then, unhelpfully, labels the result "GB". Nothing is missing — the two systems count in different bases and one of them uses the other one’s names.
A worked example
Why 1024 GB is not 1 TiB
- Entered
- 1024 GB
- Assumed
- that 1024 of something makes the next unit up
- 1024 GB = 1,024,000,000,000 bytes
- ÷ 1,000 = 1.024 TB
- ÷ 1,073,741,824 = 953.67 GiB
- 1 TiB would be 1,099,511,627,776 bytes
1024 GB = 1.024 TB = 953.67 GiB — not 1 TiB
The habit of stepping by 1024 belongs to the binary units only. Applying it to decimal ones gives a number that looks tidy and is wrong by 7.4%. This is the single most common mistake in storage arithmetic, and it is why the two families have separate names.
How to use this calculator
- Pick the unit you actually have. The dropdown lists decimal units (KB, MB, GB) and binary ones (KiB, MiB, GiB) separately, with their sizes spelled out.
- If the figure came from a product page, an invoice or a network speed, it is decimal — choose GB.
- If it came from a file manager, a disk utility or a download progress bar, it is almost certainly binary — choose GiB, even if the software wrote "GB".
- Read both families in the results. They are shown side by side and never blended.
The missing gigabytes are not missing
Drive manufacturers define a gigabyte as 1,000,000,000 bytes. Operating systems define it as 1,073,741,824 — two to the thirtieth power. The same physical drive therefore reads as "1 TB" on the box and about 931 GB in your file manager.
The gap widens with size: it is roughly 2.4% at kilobytes but nearly 10% at terabytes. Nothing is lost; the two systems simply count differently.
Bits versus bytes
A byte is eight bits. Storage is measured in bytes, but network speeds are quoted in bits per second — which is why a "100 Mbps" connection downloads at about 12.5 MB/s at best.
The capital B means bytes, lowercase b means bits. It is a one-character difference with an eightfold consequence.
How much space things actually take
A high-quality photograph from a modern phone runs 3 to 5 MB. A minute of 1080p video is roughly 60 to 100 MB, and 4K four times that. A compressed music track is around 5 MB, an ebook under 1 MB, and a feature film between 1 and 8 GB depending on resolution and codec.
This is why video dominates storage planning while documents are effectively free. A thousand text files rarely fill what a single hour of 4K footage consumes.
Formatted capacity and overhead
Beyond the decimal-versus-binary difference, filesystems reserve space for their own structures — allocation tables, journals and metadata — typically a small percentage of the drive. Solid-state drives also reserve hidden capacity for wear levelling.
Filesystems also allocate in fixed blocks, so a 1 KB file may occupy 4 KB on disk. With thousands of very small files, that rounding becomes visible in the total.
Formula & methodology
What this calculator assumes
- Decimal prefixes take decimal values, per IEC 80000-13 and the SI. Storage capacity, network speeds and data caps are all quoted this way.
- Binary prefixes are listed separately as KiB, MiB, GiB and so on. Operating systems generally count in these while still writing "GB", which is why a 1 TB drive displays as about 931 GB.
- The two families are never blended in the results. Reporting a 1024-based quantity under a decimal name is the error this page exists to explain.
Sources
- IEC 80000-13:2008, Quantities and units — Part 13: Information science and technology. Defines the binary prefixes kibi, mebi and gibi.
- Bureau International des Poids et Mesures, The International System of Units (SI), 9th edition, 2019 — the decimal prefixes.
The two families, side by side
| Decimal | Bytes | Binary | Bytes | Gap |
|---|---|---|---|---|
| 1 KB | 1,000 | 1 KiB | 1,024 | 2.4% |
| 1 MB | 1,000,000 | 1 MiB | 1,048,576 | 4.9% |
| 1 GB | 1,000,000,000 | 1 GiB | 1,073,741,824 | 7.4% |
| 1 TB | 1,000,000,000,000 | 1 TiB | 1,099,511,627,776 | 10.0% |
| 1 PB | 1,000,000,000,000,000 | 1 PiB | 1,125,899,906,842,624 | 12.6% |
The gap compounds: each step multiplies it by another 2.4%. That is why the discrepancy is barely noticeable on a memory card and impossible to miss on a multi-terabyte drive.
Which system does what
| Where the number came from | System | Written as |
|---|---|---|
| Drive or phone storage on the box | Decimal | GB, TB |
| Network and broadband speeds | Decimal | Mbps, Gbps |
| Windows File Explorer | Binary | Labelled GB, actually GiB |
| macOS Finder (since 10.6) | Decimal | GB |
| Linux, most disk utilities | Binary, usually honest | GiB |
| RAM and memory modules | Binary | Labelled GB, actually GiB |
macOS switched to decimal in 2009, which is why the same drive reports differently on a Mac and a PC. Memory is the one place binary is genuinely correct, because RAM really is addressed in powers of two.
Frequently asked questions
What are KiB, MiB and GiB?
They are the unambiguous binary units — a GiB is exactly 1,073,741,824 bytes. IEC standardised them in 1998 precisely to end this confusion, though consumer software largely ignores them.
Why does my 1 TB drive show as 931 GB?
Because the manufacturer counted in decimal — a trillion bytes — and your file manager divided by 1,024 three times and still wrote "GB". The drive holds exactly what was advertised; 931 GiB and 1 TB are the same amount of storage.
Is 1024 GB the same as 1 TB?
No. 1024 GB is 1.024 TB, and it is 953.67 GiB. Stepping by 1,024 only applies to the binary units — 1024 GiB is 1 TiB.
Which should I use?
Decimal for anything sold, transmitted or advertised: storage capacity, broadband speeds, data caps. Binary for what an operating system reports about files and memory.
Why does my 1 TB drive show 931 GB?
The manufacturer counts 1 TB as 10¹² bytes; the operating system divides by 2⁴⁰. Same drive, two counting conventions, roughly 9% apparent difference.
What comes after a terabyte?
Petabyte, exabyte, zettabyte and yottabyte, each a further factor of 1,024 in binary terms.