Data size converter

What is a Data Size Converter?

Storage sizes come in two systems that look almost identical. Decimal units (KB, MB, GB, TB) use powers of 1000 and are used by drive manufacturers and networking. Binary units (KiB, MiB, GiB, TiB) use powers of 1024 and are what Windows reports, even though it labels them GB. This converter translates between all of them.

How to use it

Enter a value and choose its unit.
Read the equivalent in every decimal and binary unit.

The two systems

Decimal (SI): 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, 1 GB = 10^9 bytes, 1 TB = 10^12 bytes.
Binary (IEC): 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes, 1 GiB = 1,073,741,824 bytes, 1 TiB = 2^40 bytes.

Why your 1 TB drive shows 931 GB

A 1 TB drive holds 1,000,000,000,000 bytes. Divided by 1,073,741,824 bytes per GiB, that is 931.3 GiB. Windows displays this as 931 GB, so the capacity seems to disappear, but nothing is missing; it is just a different unit. macOS uses decimal units since 10.6, so it shows 1 TB.

The gap grows with size

KB vs KiB: 2.4% difference
GB vs GiB: 7.4% difference
TB vs TiB: 10% difference
PB vs PiB: 12.6% difference

Other tips

Bits vs bytes: network speeds are in bits (Mbps); file sizes are in bytes (MB). Divide by 8.
RAM is always sold in binary sizes, so 16 GB of RAM is really 16 GiB.
Kubernetes and Docker accept both: 512Mi is binary, 512M is decimal.

Frequently Asked Questions

What is the difference between GB and GiB?

A GB is 1,000,000,000 bytes, while a GiB is 1,073,741,824 bytes. A GiB is about 7.4 percent larger.

Why does my hard drive show less space than advertised?

Manufacturers use decimal units, while Windows reports binary units labelled as GB. A 1 TB drive appears as about 931 GB.

Is 1 KB 1000 or 1024 bytes?

Officially 1000 bytes. 1024 bytes is a KiB, although many programs still call it KB.

How do I convert Mbps to MB per second?

Divide by 8. A 100 Mbps connection transfers at most 12.5 MB per second.