Convert data sizes without mixing up the units

GB and GiB can give different numbers for exactly the same data.

FluffyBench's Data size converter gives you the number in the unit you need.

FluffyBench · 3 min read · Reviewed October 15, 2026

What's the difference between KB and KiB?

Think of KB and KiB as two rulers with different-sized marks: the same pile of bytes gets a different reading. The little 'i' names the binary ruler; each binary unit holds more bytes than its decimal partner.

KB / KiB: 1,000 bytes and 1,024 bytes, respectively. MB / MiB: 1,000,000 bytes and 1,048,576 bytes, respectively. GB / GiB: 1,000,000,000 bytes and 1,073,741,824 bytes, respectively. TB / TiB: 1,000,000,000,000 bytes and 1,099,511,627,776 bytes, respectively. — Within each pair, the rulers start together and share a scale. The dotted line marks where the decimal unit ends; the labels give exact byte counts for one unit. How we reviewed

Why does 1 TB become about 931 GiB?

One TB is about 931.32 GiB. A GiB holds more bytes than a GB, so counting in GiB gives a smaller reading than counting the same amount in GB.

1 TB is 1,000,000,000,000 bytes. Divide by 1,073,741,824 bytes per GiB to get approximately 931.32 GiB. — The byte count stays fixed while the unit changes.

Unit conversion alone can't explain or diagnose other capacity differences on a drive.

Doing it in FluffyBench's Data size converter

Here's a complete conversion from a decimal terabyte label to a GiB reading. Match From to the label you have and To to the unit your destination asks for.

Step 1. Start with the units: From is the label you have; To is the label you need.
1. Open From to choose the starting unit.
2. Open To to choose the result unit.
Step 2. For a terabyte label, choose TB in the Decimal group. Choosing a unit closes the picker.
1. Find a unit filters the choices by name or symbol.
2. Choose Terabyte (TB).
Step 3. For a binary gigabyte reading, choose GiB in the Binary group.
1. Choose Gibibyte (GiB).
Step 4. Enter 1 in Terabytes; FluffyBench updates the result as you type.
1. Enter 1.
Step 5. Check the Gibibytes heading and result before using Copy. Copy puts the number on your clipboard without a unit or grouping commas, so add GiB when sharing it.
1. Check that Gibibytes is the unit you need.
2. Read the converted amount.
3. Copy the result number.

Need FluffyBench's Number base converter to read an integer in binary, decimal or hexadecimal?

Number bases

Bits or bytes?

Bit and Byte are also choices in FluffyBench's Decimal picker group. A lowercase b means bit; an uppercase B means byte, which holds 8 bits—so those labels aren't interchangeable.

8 bit cells, containing 01101001, grouped into one byte. — The bracket groups the bits into one byte.

How we reviewed

Reviewed October 15, 2026

Data-size conversion multiplies the amount by its source unit's byte size divided by the target unit's byte size: decimal prefixes use powers of 1,000 and binary prefixes use powers of 1,024.

FluffyBench's Data size converter updates as you type, in this page, without a conversion request.

Data-size inputs must be non-negative finite numbers. Decimal and exponent notation are accepted; nonzero inputs or results that become zero in browser arithmetic report a numeric-range error.

For "Enter a decimal number for Value.", leave unit text and grouping commas out of the amount. Negative numbers and amounts beyond browser arithmetic give a numeric-limit message.

The calculator formats converted numbers to up to 14 significant digits; the display may round the final digit. The TB-to-GiB diagram rounds that result to two decimal places.

Storage display conventions vary. This arithmetic does not inspect a drive, its partitions, or its file system.

The main Copy button and the copy buttons beside other units copy the ungrouped result number without its unit. There's no file download for data-size results.