MB Networks
TOOL-10 · Sizes
Data size converter
Convert between bits, bytes, and every common unit — decimal (SI) and binary (IEC).
Quick values
Common sizes
Decimal — SI
1 KB = 1,000 B · storage marketing, network speedsBinary — IEC
1 KiB = 1,024 B · OS file sizes, RAM1 TB = 1,000,000,000,000 bytes).
Operating systems measure in binary (1 TiB = 1,099,511,627,776 bytes), so a “1 TB” drive shows
as ~931 GiB in Windows/Linux. RAM is always sold and measured in binary — 16 GB of RAM = 16 GiB.
Why your download shows a different number than expected
Storage manufacturers and most operating systems disagree on what "GB" means. Manufacturers use decimal (SI) units — 1GB = 1,000,000,000 bytes, powers of 1000. Windows historically labeled binary (IEC) units — what should be called GiB, 1,073,741,824 bytes, powers of 1024 — with the same "GB" label. That mismatch is exactly why a "1TB" drive shows roughly 931GB in Windows: the drive is a true decimal terabyte, and Windows is measuring and labeling it in binary units under the same name.
Bits vs. bytes — the other common mix-up
Network speeds are conventionally quoted in bits per second (Mbps), while file sizes and storage are quoted in bytes (MB, GB) — divide a bits-based speed by 8 to get bytes, which is why a "100 Mbps" connection tops out around 12.5 MB/s in a download manager, not 100.
Why does my 1TB drive show as 931GB in Windows?
The drive manufacturer used decimal units (1TB = 1,000,000,000,000 bytes, the actual, correct SI definition); Windows displays capacity in binary units (multiples of 1024) but historically mislabeled them with decimal unit names. 1,000,000,000,000 bytes ÷ 1024³ ≈ 931 — same physical capacity, different unit convention, nothing missing or defective.
What's the actual difference between GB and GiB?
GB (decimal/SI) = 1,000,000,000 bytes. GiB (binary/IEC) = 1,073,741,824 bytes — about 7.4% larger. Storage vendors use GB; most operating systems' binary math uses GiB-sized units while frequently still displaying the GB label, which is the entire source of the confusion.
Why is my download speed in Mbps but my file size in MB?
Different conventions for different contexts, both long-established: network/connection speeds are quoted in bits per second (Mbps), file and storage sizes in bytes (MB, GB). Since 1 byte = 8 bits, divide a bits-based speed by 8 to estimate real download speed in bytes per second.
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