Data Storage Converter
Type a size in any unit and see it instantly in bits, bytes, decimal KB/MB/GB/TB/PB/EB and binary KiB/MiB/GiB/TiB/PiB/EiB, side by side with exact values. Everything is calculated privately in your browser.
Decimal SI · powers of 1000
Binary IEC · powers of 1024
Bits networks & bandwidth
Why does my drive look smaller?
Quick reference: decimal vs binary prefixes
How to use the Data Storage Converter
- Enter a size in the box, for example 1 or 1.5. You can also type the unit, like 500 GB or 64 KiB.
- Pick the unit you are converting from (decimal KB/MB/GB, binary KiB/MiB/GiB, bits or bytes).
- Read the results: decimal units are on the left, binary units on the right, bit units below.
- Copy a value with the Copy button next to it, or press Convert to refresh.
- Check the drive panel to see how much space Windows and macOS will report for that size.
Decimal vs binary units: the two meanings of "GB"
Computers count in powers of two, so early software used "kilobyte" for 1,024 bytes because it was close to 1,000. As drives grew, the gap between the two meanings grew too: 2.4% at the kilobyte level, 7.4% at the gigabyte and almost 10% at the terabyte. In 1998 the International Electrotechnical Commission (IEC) introduced separate binary prefixes – kibi (Ki), mebi (Mi), gibi (Gi), tebi (Ti) – so that KB, MB, GB and TB mean 1000-based values and KiB, MiB, GiB and TiB mean 1024-based values.
- Decimal (SI): hard drive and SSD makers, USB sticks, macOS (since 10.6), iOS, most Linux file managers, network speeds and data plans.
- Binary (IEC): RAM sizes, Windows File Explorer (which shows binary values but labels them KB, MB, GB), many command-line tools such as
df -handfree.
Why a 1 TB drive shows 931 GB
A drive sold as 1 TB contains 1,000,000,000,000 bytes. Windows divides that by 1,024 × 1,024 × 1,024 = 1,073,741,824 to get gigabytes, so it shows 931.32 GB (really 931.32 GiB). The capacity is identical; only the unit differs. The formatted size is a little lower again because the file system, recovery partition and over-provisioning reserve some space.
| Advertised size | Bytes | Windows shows | macOS shows |
|---|---|---|---|
| 128 GB | 128,000,000,000 | 119.21 GB | 128 GB |
| 256 GB | 256,000,000,000 | 238.42 GB | 256 GB |
| 500 GB | 500,000,000,000 | 465.66 GB | 500 GB |
| 512 GB | 512,000,000,000 | 476.84 GB | 512 GB |
| 1 TB | 1,000,000,000,000 | 931.32 GB (0.909 TB) | 1 TB |
| 2 TB | 2,000,000,000,000 | 1.82 TB | 2 TB |
| 4 TB | 4,000,000,000,000 | 3.64 TB | 4 TB |
| 8 TB | 8,000,000,000,000 | 7.28 TB | 8 TB |
| 16 TB | 16,000,000,000,000 | 14.55 TB | 16 TB |
Conversion formulas and examples
To convert, multiply by the size of the source unit in bytes and divide by the size of the target unit. Going up one decimal prefix divides by 1,000; going up one binary prefix divides by 1,024.
- KB to MB: 2,500 KB ÷ 1,000 = 2.5 MB. In binary, 2,500 KiB ÷ 1,024 = 2.44 MiB.
- GB to TB: 750 GB ÷ 1,000 = 0.75 TB.
- GB to GiB: GB × 1,000,000,000 ÷ 1,073,741,824, or GB × 0.9313. So 64 GB = 59.6 GiB.
- GiB to GB: GiB × 1.073741824. So 16 GiB of RAM = 17.18 GB.
- Bits to bytes: divide by 8. A 1 Gbit/s link moves at most 125 MB per second; see the Mbps to MB per second converter for download times.
Watch the case of the letter b: Mb or Mbit is megabits, MB is megabytes – eight times larger. Internet plans are sold in megabits per second, while file sizes are shown in megabytes.
Frequently asked questions
How many MB are in a GB?
In decimal (SI) units, which drive makers, macOS and most network figures use, 1 GB = 1,000 MB. In binary units, 1 GiB = 1,024 MiB. Windows uses the binary values but labels them GB and MB, which is why both answers are common.
Why does my 1 TB drive show only 931 GB?
The drive really has 1,000,000,000,000 bytes (1 TB in decimal). Windows divides by 1,024 three times instead of by 1,000, so it shows 1,000,000,000,000 / 1,073,741,824 = 931.32 GiB, labelled GB. No space is missing; the units are different. A small further amount is used by the file system.
What is the difference between KB and KiB?
KB (kilobyte) means 1,000 bytes under the SI and IEC standards. KiB (kibibyte) means 1,024 bytes. The IEC introduced KiB, MiB, GiB and so on in 1998 so binary sizes have their own unambiguous names.
How many bytes are in a gigabyte?
A gigabyte (GB) is 1,000,000,000 bytes. A gibibyte (GiB) is 1,073,741,824 bytes (2 to the 30th power), about 7.4% more.
How do I convert bits to bytes?
Divide by 8, because one byte is eight bits. For example, a 100 Mbit/s connection moves at most 12.5 MB of data per second. Lowercase b usually means bits and uppercase B means bytes.
Is RAM measured in GB or GiB?
Memory is built in powers of two, so a 16 GB RAM stick actually has 16 GiB (17,179,869,184 bytes). This is the main place where GB is still commonly used in the binary sense (the JEDEC convention).
How precise are the results?
The converter uses whole-number (BigInt) arithmetic, so results are exact. Values are shown in full when they fit in 17 significant digits; longer results are rounded to 12 significant digits and marked with ≈.