GB and GiB: differences and how to convert them

Short answer

GB and GiB measure information in bytes, but use different scales. A gigabyte uses powers of 1,000 and a gibibyte uses powers of 1,024. Therefore, a device advertised with 1 TB may correspond to about 931.32 GiB without any bytes disappearing during the conversion.

The safe way to interpret a figure is to keep the symbol, identify the factor it represents and, if there is a doubt, return to the exact amount of bytes.

Quick answers for common capacities

Each pair describes the same number of bytes. This table does not estimate free space after formatting; partitions, metadata, and reserved areas can reduce the available figure further.

Exact definitions

Decimal prefixes follow the International System:

1 kB = 1,000 B
1 MB = 1,000 kB = 1,000,000 B
1 GB = 1,000 MB = 1,000,000,000 B
1 TB = 1,000 GB = 1,000,000,000,000 B

Binary prefixes represent powers of 1,024:

1 KiB = 1,024 B
1 MiB = 1,024 KiB = 1,048,576 B
1 GiB = 1,024 MiB = 1,073,741,824 B
1 TiB = 1,024 GiB = 1,099,511,627,776 B

The letter i distinguishes the binary prefix: Ki, Mi, Gi and Ti. NIST collects these names and symbols adopted to prevent k, M or G sometimes meaning powers of ten and other times powers of two:

• NIST — Binary Prefix Definitions
• NIST SP 330 — Decimal and Binary Prefixes
• BIPM — International System Brochure

How much 1 GB and 1 GiB differ

The two exact quantities are:

1 GB  = 1,000,000,000 B
1 GiB = 1,073,741,824 B

A gibibyte contains 73,741,824 B more than a gigabyte. Relative to a gigabyte, that difference is approximately 7.374%. The inverse relationship is:

1 GB = 0.931322574615478515625 GiB

It is not advisable to memorize a single percentage for any comparison. It’s more reliable to use the exact factors, because the cumulative difference changes with the unit and direction of conversion.

Example: why 1 TB is equivalent to about 931.32 GiB

We start from the exact decimal capacity:

1 TB = 1,000,000,000,000 B

Each gibibyte contains 1,073,741,824 B. Divide the byte count by bytes per gibibyte:

1,000,000,000,000 B ÷ 1,073,741,824 B/GiB
= 931.322574615478515625 GiB

The figures 1 TB and 931.32 GiB describe the same number of bytes with two different scales. They do not represent used space on their own, a hidden partition or lost capacity.

You can reproduce the calculation and copy the exact result in the storage unit converter.

Other known examples

500 GB to GiB

500 GB = 500,000,000,000 B
500,000,000,000 ÷ 1,073,741,824
= 465.6612873077392578125 GiB

Rounded to two decimal places: 465.66 GiB.

2TB to GiB and TiB

2 TB = 2,000,000,000,000 B
2 TB = 1,862.64514923095703125 GiB
2 TB = 1.818989403545856475830078125 TiB

16 GiB to GB

16 GiB = 17,179,869,184 B
16 GiB = 17.179869184 GB

In this sense the decimal figure is larger, because each GB represents less bytes than a GiB.

Formulas to convert

The number of bytes is the bridge between both systems.

From GB to GiB:

GiB = GB × 1,000,000,000 ÷ 1,073,741,824

From GiB to GB:

GB = GiB × 1,073,741,824 ÷ 1,000,000,000

From TB to TiB:

TiB = TB × 1,000,000,000,000 ÷ 1,099,511,627,776

Keeping the factors as integers until the last operation reduces the errors. If the initial quantity contains decimals, it can be represented as a fraction instead of converting it to floating point soon.

Why different figures may appear in two interfaces

Commercial capacity is usually expressed with decimal prefixes. A system tool may show the same quantity with binary prefixes, decimal prefixes or an ambiguously labeled binary calculation. Not every system or version follows the same display convention.

To compare two screens:

1. Write down the complete symbol that each one shows.
2. Find the number of bytes if available.
3. Convert both figures with the same definition.
4. Only then investigate reserved space, partitions or metadata.

The symbol alone does not reveal which formula an interface used if it does not document its convention. The byte count lets you verify it.

Rated capacity and available space are not the same

The decimal/binary conversion accounts for a presentation difference, but usable space may also vary for other reasons:

• partition tables and recovery partitions;
• file system metadata;
• reserved or defective blocks;
• snapshots and files that do not appear in a simple view;
• redundancy in RAID or other storage schemes;
• capacity reserved by the device or its controller.

That is why you should not attribute every difference to GB versus GiB, nor use the conversion to promise how much free space a computer will have after formatting.

Bits and bytes are a separate distinction

The comparison between decimal and binary should not be confused with bits vs. bytes:

1 B = 8 bit

GB and GiB contain bytes. Gbit contains decimal bits. Furthermore, a rate as Gbit/s includes “per second” and does not represent a static capacity.

If you want to relate capacity to speed, use the bandwidth and transfer time calculator. It first converts 1 TB to bits and then divides by a rate expressed in bit/s to get seconds.

Practical method to avoid mistakes

1. Copy the figure without changing its symbol.
2. Distinguish b from bit and B from byte.
3. Check if the prefix is decimal (k, M, G, T) or binary (Ki, Mi, Gi, Ti).
4. Convert to exact bytes or bits.
5. Divide by the exact factor of the target unit.
6. Keep the exact result and round only for presentation.
7. Indicate how many decimal places you used if rounding affects a decision.

This procedure works the same for MB/MiB, GB/GiB and TB/TiB.

Common errors

• Write GB when the calculation uses GiB because “it has always been used that way.”
• Treat 1 GB as 1,024 MB; the correct decimal definition uses 1,000.
• Divide by eight to solve for GB vs. GiB; that operation converts bits and bytes, not prefixes.
• Round to an integer before finishing the conversion.
• Compare advertised capacity with free space without considering the file system.
• Assume that any screen labeled GB necessarily uses powers of 1,000.
• Confuse GB capacity with Gbit/s rate.

Frequently asked questions

Is 1 TB 1,000 GB?

Yes, when TB and GB are used according to their decimal definitions. They are also exactly 1,000,000,000,000 B.

Is 1 TiB 1,024 GiB?

Yes. Both are binary multiples: 1 TiB = 1,024 GiB.

Should I use GB or GiB?

Use the symbol that corresponds to the real factor. If you work with powers of 1,000, use GB. If you work with powers of 1,024, use GiB. If you quote an ambiguous interface, also add the byte number.

Why doesn’t the converter round up automatically?

Because the appropriate number of decimals depends on the use. A visual estimate can accept two decimal places; a partition check or a test may need to preserve the exact equivalence.

Does a difference between TB and TiB mean there is a lack of capacity?

No. First check if the two figures describe the same number of bytes with different scales. It then separates any additional differences caused by partitions, metadata or reserved space.