Digital Storage Converter
Bytes, KB, MB, GB and TB alongside binary KiB, MiB and GiB, so drive sizes finally add up
Bytes, KB, MB, GB and TB alongside binary KiB, MiB and GiB, so drive sizes finally add up. No data leaves your browser – every conversion happens locally.
Decimal KB versus binary KiB
There are two systems and this tool includes both. KB, MB, GB and TB are decimal (SI) units: 1 KB is 1,000 bytes and 1 GB is a billion bytes. KiB, MiB and GiB are binary: 1 KiB is 1,024 bytes and 1 GiB is 1,073,741,824 bytes.
Drive makers use decimal. Windows reports sizes in binary but labels them "GB", which is where the missing space comes from. macOS switched to decimal in 2009 (Snow Leopard), so the same drive can show different sizes on a Mac and a PC.
Storage size reference
| 1 KB | 1,000 bytes |
| 1 KiB | 1,024 bytes |
| 1 GB → MB | 1,000 MB |
| 1 GiB | 1,073,741,824 bytes |
| 1 TB | 1,000 GB |
| 1 GB → bits | 8,000,000,000 bits |
Good to know
Why your hard drive shows less space than advertised
Drive manufacturers use decimal (1 GB = 1,000,000,000 bytes). Windows uses binary (1 GB = 1,073,741,824 bytes) while still calling it GB. A '1 TB' drive shows as ~931 GB in Windows but 1 TB on a Mac, which has used decimal since 2009. Neither is wrong; they're using different definitions.
Worked examples
A "1 TB" drive
10¹² bytes is 931.3 GiB. Windows will show it as roughly 931 GB, and nothing is actually missing.
A 64 GB phone
That's 59.6 GiB before the operating system takes its share, so expect around 50 GiB usable.
A single-layer DVD
4.7 GB is 4.38 GiB, which is why burning software says a 4.5 GiB file won't fit.
What advertised drive sizes show up as
Storage is sold in decimal gigabytes, while Windows and many apps report binary gibibytes. This table shows the size your computer will report before any space is taken by the operating system or formatting.
| Advertised | Bytes | Shown as (GiB) |
|---|---|---|
| 16 GB | 16 billion | 14.9 GiB |
| 32 GB | 32 billion | 29.8 GiB |
| 64 GB | 64 billion | 59.6 GiB |
| 128 GB | 128 billion | 119.2 GiB |
| 256 GB | 256 billion | 238.4 GiB |
| 512 GB | 512 billion | 476.8 GiB |
| 1 TB | 1 trillion | 931.3 GiB |
| 2 TB | 2 trillion | 1,862.6 GiB |
| 4 TB | 4 trillion | 3,725.3 GiB |
Capital B, small b and RAM
Case matters. MB is megabytes and Mb is megabits, eight times smaller. Phone plans, router boxes and file sizes mix the two freely, so a "500 Mb" limit is 62.5 MB of data. When a spec sheet is unclear, look for "bit" or "byte" spelled out.
RAM is the exception to the decimal rule. Memory is always built in powers of two, so 8 GB of RAM is really 8 GiB, or 8,589,934,592 bytes. Use the GiB option when converting memory sizes and GB when converting drive or file sizes.