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Bytes to GB Converter (GB and GiB)
Convert bytes, KB, MB, GB, TB and PB in decimal and binary units side by side, and see what size Windows will show for a drive.
| Decimal (SI, ×1,000) | Binary (IEC, ×1,024) |
|---|
“GB” means two different numbers depending on who’s counting. Drive and memory card makers use decimal units, where 1 GB is 1,000,000,000 bytes. Windows calculates in binary units, where the same label stands for 1,073,741,824 bytes. This converter shows a value in both systems side by side, so you can turn bytes into GB, MB or TB and see why a new drive looks smaller in File Explorer than on the box.
How to use the bytes to GB converter
- Enter a number.
- Pick its unit: bytes, KB, MB, GB, TB or PB (decimal), or KiB, MiB, GiB, TiB or PiB (binary).
- Read the same amount in every decimal unit (1 KB = 1,000 bytes) next to every binary unit (1 KiB = 1,024 bytes).
- Check the line “A drive sold as X shows about Y in Windows” to see what size Windows will report for a drive of that capacity.
How it works
Decimal units use the SI prefixes, which are powers of 10. Binary units use the prefixes the International Electrotechnical Commission (IEC) adopted in December 1998 for powers of 2: kibi, mebi, gibi, tebi and pebi. NIST notes that these binary prefixes are not part of the SI.
| Decimal (SI) | Bytes | Binary (IEC) | Bytes |
|---|---|---|---|
| 1 KB (kilobyte) | 1,000 | 1 KiB (kibibyte) | 1,024 |
| 1 MB (megabyte) | 1,000,000 | 1 MiB (mebibyte) | 1,048,576 |
| 1 GB (gigabyte) | 1,000,000,000 | 1 GiB (gibibyte) | 1,073,741,824 |
| 1 TB (terabyte) | 1,000,000,000,000 | 1 TiB (tebibyte) | 1,099,511,627,776 |
| 1 PB (petabyte) | 1,000,000,000,000,000 | 1 PiB (pebibyte) | 1,125,899,906,842,624 |
So the formulas are:
- GB = bytes ÷ 1,000,000,000
- GiB = bytes ÷ 1,073,741,824
The gap grows with every step: a KiB is 2.4% larger than a KB, a GiB 7.4% larger than a GB and a TiB almost 10% larger than a TB.
Why Windows shows less than the box
Drive makers state capacity in decimal units. Windows reports storage in binary units: Microsoft’s own documentation notes that a 2 TB drive appears as 1.82 TiB in Windows. File Explorer shows those binary values with the labels KB, MB, GB and TB, which is why the number looks smaller. The bytes are all there; only the unit changed.
Worked examples
1 TB drive → 931.32 GiB
1 TB = 1,000,000,000,000 bytes. 1,000,000,000,000 ÷ 1,073,741,824 = 931.32 GiB, which Windows shows as about 931 GB.
1,500,000,000 bytes → 1.5 GB or 1.40 GiB
1,500,000,000 ÷ 1,000,000,000 = 1.5 GB. 1,500,000,000 ÷ 1,073,741,824 = 1.40 GiB (1.3970, rounded).
16 GiB of RAM → 17.18 GB
Memory is built in powers of 2, so 16 GiB = 16 × 1,073,741,824 = 17,179,869,184 bytes, which is 17.18 GB in decimal units.
4,096 bytes → 4 KiB
4,096 ÷ 1,024 = 4 KiB, while 4,096 ÷ 1,000 = 4.096 KB.
What size Windows shows for common drives
| Sold as | Bytes | Binary size |
|---|---|---|
| 128 GB | 128,000,000,000 | 119.21 GiB |
| 256 GB | 256,000,000,000 | 238.42 GiB |
| 500 GB | 500,000,000,000 | 465.66 GiB |
| 512 GB | 512,000,000,000 | 476.84 GiB |
| 1 TB | 1,000,000,000,000 | 931.32 GiB |
| 2 TB | 2,000,000,000,000 | 1,862.65 GiB (1.82 TiB) |
| 4 TB | 4,000,000,000,000 | 3,725.29 GiB (3.64 TiB) |
Related guides
- Running out of space? Microsoft recommends keeping roughly 10 to 15 percent of the system drive free; our guide to why your computer is so slow shows how to free it up.
- Storage Sense and temporary file cleanup are covered step by step in how to speed up Windows 11.
- See why a kibibyte is 1,024 bytes by converting 10000000000 in the binary to decimal converter.
Frequently asked questions
How many bytes are in a GB?
In decimal (SI) units, 1 GB is exactly 1,000,000,000 bytes. The binary unit, 1 GiB (gibibyte), is 1,073,741,824 bytes (2^30). Drive makers use GB; Windows calculates sizes in the binary unit.
How do I convert bytes to GB?
Divide the number of bytes by 1,000,000,000 for GB, or by 1,073,741,824 for GiB. For example, 1,500,000,000 bytes is 1.5 GB or about 1.40 GiB.
Why does my 1 TB drive show as 931 GB in Windows?
The drive holds 1,000,000,000,000 bytes, as the label says. Windows divides by 1,024 at each step instead of 1,000, which gives 931.32 binary gigabytes, and shows that number with the GB label. No space is missing.
What's the difference between GB and GiB?
GB (gigabyte) uses the SI prefix giga, 10^9 bytes. GiB (gibibyte) uses the binary prefix gibi that the IEC adopted in 1998, 2^30 bytes. A GiB is about 7.4% larger than a GB.
Is a kilobyte 1,000 or 1,024 bytes?
Under the SI and IEC standards, a kilobyte (kB) is 1,000 bytes and a kibibyte (KiB) is 1,024 bytes. Older software and Windows still use 'KB' for 1,024 bytes, which is why the converter shows both.
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