Phones, apps & storage

File Size Converter

Converts a size into every unit at once, decimal and binary side by side, so you can see why a 1 TB drive shows up as 931 GB. The gap is not a defect and nothing is missing — the two sides are counting differently.

Amount

Unit

Quick picks

The same quantity in every unit.
Unit	Decimal (base 1,000)	Unit	Binary (base 1,024)

Why a 1 TB drive shows 931 GB

The manufacturer sells 1,000,000,000,000 bytes and calls it a terabyte. Windows divides that by 1,024 three times, gets 931.32, and labels the result "GB" — when what it has actually computed is 931 GiB. Nothing is missing and no space has been lost; two different units are wearing the same label.

1 KB = 1,000 bytes 1 KiB = 1,024 bytes 1 MB = 1,000,000 1 MiB = 1,048,576 1 GB = 1,000,000,000 1 GiB = 1,073,741,824 1 TB = 1,000,000,000,000 1 TiB = 1,099,511,627,776 the gap compounds: 2.4% at KB, 4.9% at MB, 7.4% at GB, 10.0% at TB

Who uses which

Which convention each side of the industry follows.
Context	Convention	Consequence
Drive and phone capacities	Decimal	The number on the box is the larger one
Windows Explorer	Binary, labelled as decimal	The source of the "missing space" question
macOS since 10.6	Decimal	Matches the box; a 1 TB drive shows 1 TB
Linux `ls -h`	Binary, labelled correctly as KiB/MiB	No ambiguity
RAM	Always binary	8 GB of RAM really is 8 GiB — memory is addressed in powers of two
Network speeds	Decimal, and in bits	100 Mbps is 12.5 MB/s

Bits and bytes

Eight bits make a byte. Storage is quoted in bytes, bandwidth in bits, and the lowercase b against uppercase B is the only thing distinguishing them — 100 Mb is one eighth of 100 MB. This convention dates to when serial links genuinely moved one bit at a time, and it survives mainly because a bigger number sells better.

Questions people ask about this

What is the difference between GB and GiB?

A gigabyte is 1,000,000,000 bytes; a gibibyte is 1,073,741,824. GiB is 7.4% larger. Storage manufacturers use GB, Windows displays GiB while labelling it GB, and RAM is always counted in binary units regardless of the label. Both are correct definitions of different units.

Why does my 1TB hard drive only show 931GB?

Because the drive holds 1,000,000,000,000 bytes and your operating system is dividing by 1,024 rather than 1,000, producing 931.32 — then labelling that number "GB" when it is really GiB. No space is missing; formatting overhead removes only a further fraction of a percent on top.

How many MB are in a GB?

1,000 MB in a decimal gigabyte, or 1,024 MiB in a gibibyte. In casual use people say 1,024 and mean the binary units, which is right for RAM and for what Windows displays, and wrong for the capacity printed on a drive.

Is 100 Mbps the same as 100 MB/s?

No — it is 12.5 MB/s. Network speeds are quoted in megabits and files are measured in megabytes, and there are eight bits to a byte. The lowercase b in Mbps is the only thing marking the difference, and it is the most common unit confusion in computing.

Where these numbers come from

Rates on this page were last checked against the published price lists on September 3, 2026. Grading companies change fees and pause tiers without notice — confirm the total on the submission form before you pay.