File Size Converter
Convert between file size units
Decimal (1000)
Binary (1024)
Why does my drive show less than the box says?
500 GB on the box is 465.6613 GiB. Windows labels that "GB", so you see about 465.66 GB — 6.9% "missing", though no bytes are lost. macOS shows the full 500 GB.
Reading results never uses a trial use. Copying, saving or printing uses 1 per visit.
About File Size Converter
Converts a file or storage size between bytes, KB, MB, GB, TB and PB in both systems: decimal (1 GB = 1,000,000,000 bytes, used by drive makers, phone makers and networks) and binary (1 GiB = 1,073,741,824 bytes, used by Windows, many file tools and memory).
Enter a value and pick its unit. Both columns update at once: the decimal units (KB, MB, GB...) and the binary units (KiB, MiB, GiB...). The box below shows what a drive sold in decimal GB or TB shows up as on a computer that counts in 1024s.
That is why a 500 GB drive shows about 465 GB in Windows: the box counts 500,000,000,000 bytes, and Windows divides by 1024³ but still writes "GB". macOS divides by 1000 and shows the full 500 GB.
Watch: File Size Converter in Action
- Why does my drive show less storage than what's printed on the box?
- Storage manufacturers and operating systems sometimes use slightly different definitions of a gigabyte (1000³ bytes versus 1024³ bytes) — this discrepancy is exactly why a drive can show less capacity in your OS than advertised.
- Why is a 500 GB drive shown as about 465 GB?
- Drive makers count 1 GB as 1,000,000,000 bytes. Windows divides the same bytes by 1,073,741,824 but still prints GB, so 500 GB appears as about 465.66. No space is lost; macOS counts in 1000s and shows 500 GB.
- What is the difference between GB and GiB?
- GB means 1,000,000,000 bytes and GiB means 1,073,741,824 bytes, which is 1024 cubed. The same pattern holds for KB and KiB, MB and MiB, TB and TiB, and PB and PiB, with each binary step about 2.4 percent larger than its decimal twin per level of the ladder.
- Which should I use for an upload limit?
- It depends on who set the limit. Many services say MB and mean 1,000,000 bytes, while some tools mean 1,048,576. Enter your size both ways, compare the B rows, and when a limit is close to your file size assume the smaller value to be safe.
- Does it convert bits or megabits?
- No, only bytes and their multiples appear. For a connection speed in megabits per second, divide by 8 to get megabytes per second, then enter that result. Lowercase b stands for bits and capital B for bytes.
- Why do very small numbers show in a strange form?
- Any non-zero result below 0.0001 switches to exponent notation, such as 1.000e-7, so tiny values are not rounded down to zero. Everything else shows up to four decimal places with thousands separators in your browser's locale.
How to use File Size Converter
Type a number into Value and choose its unit in Unit. The list holds B, KB, MB, GB, TB and PB, labelled 1000, plus KiB, MiB, GiB, TiB and PiB, labelled 1024. Two panels respond at once: Decimal (1000) and Binary (1024), each showing the same amount in bytes and in every larger unit up to PB or PiB.
For a storage device, use the box beneath titled Why does my drive show less than the box says. Enter the Advertised size and choose GB or TB. The sentence below gives the matching GiB or TiB, the figure Windows reports under the old label, and the share that appears to be missing.
When to use it
Check whether a file will fit under an upload limit stated in MB, compare a 256 GB phone with a figure in a settings screen, or translate a storage allowance into bytes for a script. It also explains a common surprise: a new drive reporting less than its label. Developers can compare the B rows to confirm whether a limit means 1048576 or 1000000 bytes.
When not to use it
It converts storage sizes only, so network speeds in megabits per second need dividing by 8 yourself, because bits are not offered. It does not read a real file's size, check compression, or estimate how many photos or songs fit on a drive. For durations or transfer rates, use a converter that handles bits and time.
Tips for best results
Mind the letter case: a lowercase b means bits and an uppercase B means bytes, and this tool uses bytes. When a number looks about 7 percent off, you are most likely comparing 1000-based and 1024-based units at the gigabyte level; the gap widens with each step up, so terabytes differ by more. Use the B row if you need the exact byte count.
Limitations
Results show up to four decimal places, and very small values switch to exponent form, such as 1.000e-7. Browsers hold numbers with limited precision, so petabyte values with many digits may round. Negative values are not blocked, and an empty entry shows a dash. The drive explainer covers GB and TB only. Units larger than petabytes and smaller than a byte are not offered.
Privacy
This converter is plain arithmetic in your browser. The value, unit and advertised drive size you type are not uploaded or saved, and no file is opened: it deals with numbers only, never with the contents of any file. Nothing here is sent to a server, and nothing is kept after you close the page.
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