GB to Bytes Converter
Convert gigabytes to bytes — a billion per GB, which is why a 1 TB drive reports as 931 GB.
Updated
bytes
1,000,000,000B
1 GB = 1,000,000,000 B
Advertisement
In short
How many bytes are in 1 GB?
1,000,000,000 bytes. Multiply gigabytes by a billion, so 8 GB is 8,000,000,000 bytes. The binary unit, the gibibyte, holds 1,073,741,824 bytes — 7.37 percent more. That gap is why a drive sold as 1 TB is reported by an operating system as 931 GB.
Nothing is missing from the drive. The two figures count the same bytes in different units.
gigabytes to bytes — quick reference
| gigabytes (GB) | bytes (B) |
|---|---|
| 0.5 GB | 500,000,000 B |
| 1 GB | 1,000,000,000 B |
| 2 GB | 2,000,000,000 B |
| 4 GB | 4,000,000,000 B |
| 8 GB | 8,000,000,000 B |
| 16 GB | 16,000,000,000 B |
| 32 GB | 32,000,000,000 B |
| 64 GB | 64,000,000,000 B |
The formula, worked line by line
One multiplication by a billion for the decimal answer, or by 1,073,741,824 for the binary one. Both are below. At this rung the choice is no longer academic, because the two results differ by more than seven percent of whatever you are sizing.
“The drive did not lose 69 gigabytes. It was measured in one unit and reported in another with the same name.”
Everything else on this page follows from that. Once you know both divisors and which tools use which, the discrepancy stops being a mystery and becomes something you can predict before it appears.
bytes = gigabytes x 1,000,000,000
bytes = gibibytes x 1,073,741,824
1 GB = 10^9 = 1,000,000,000 bytes
1 GiB = 2^30 = 1,073,741,824 bytes
1,000,000,000,000 bytes / 1,073,741,824 = 931.32 GiB- Data to protect
- 200 GB decimal
- As bytes
- 200,000,000,000
- Volume provisioned
- 200 GiB
- That volume in bytes
- 214,748,364,800
- Actual headroom
- 14,748,364,800 bytes
- Spare capacity
- about 14.7 GB
Here the mismatch works in your favour, because the binary unit is the larger one. Reverse the two — 200 GB of provisioned volume holding 200 GiB of data — and you are 14.7 GB short of somewhere to put it, discovered at the end of the first full backup.
Which tools count which way
Drive manufacturers, network equipment and most cloud storage APIs use the decimal prefixes. Windows reports binary quantities under decimal names. macOS switched to decimal in 2009, which is why the same drive can report two different capacities on two machines. Linux tools vary, and many now print the unambiguous GiB.
The gap, rung by rung
- kilo, 10^3 against 2^10
- 2.4 percent
- mega, 10^6 against 2^20
- 4.86 percent
- giga, 10^9 against 2^30
- 7.37 percent
- tera, 10^12 against 2^40
- 10 percent
- peta, 10^15 against 2^50
- 12.6 percent
Each rung multiplies the last by 1.024. The petabyte row is why storage vendors and their customers settled the argument contractually: at that scale a units disagreement is worth more than the hardware in a rack.
If you carry one rule forward, make it this: a capacity is only comparable to another capacity when both are in bytes. Every other form is a label whose divisor you have to know before the number means anything.
How to use the GB to bytes converter
A gigabyte is a billion bytes, so this multiplies by 1,000,000,000. What makes the gigabyte rung worth its own page is the size of the disagreement. At kilobyte scale the two competing definitions differ by 2.4 percent, which nobody notices. At gigabyte scale they differ by 7.37 percent, which is a visible chunk of a disk.
That is where the most common complaint in computing comes from. A drive is manufactured and sold in decimal gigabytes because that is what the SI prefix means. An operating system has historically divided by powers of two and printed the decimal name anyway. The drive is honest, the operating system is consistent, and the user is short by 7.37 percent.
1,000,000,000
Bytes in one gigabyte
decimal, SI
1,073,741,824
Bytes in one gibibyte
2^30, written GiB
931.32
Gibibytes in a 1 TB drive
the missing 69 GB
Advertisement
The arithmetic behind that last figure is short and worth doing once. A terabyte drive holds 1,000,000,000,000 bytes. Divide that by 1,073,741,824 and you get 931.32. Nothing has been lost, reserved or hidden by the manufacturer. The number simply changed units on the way from the box to the screen without changing its label.
When you are provisioning rather than reading, this matters in a specific way: the figure you ask for and the figure you get may be measured differently. Asking a cloud provider for 100 GB usually gets you 100 decimal gigabytes. Formatting it and looking at the result usually shows about 93 GiB, and the shortfall will be blamed on the filesystem when it is really the units.
- 256 GB
- 256,000,000,000 B · 238.4 GiB
- 500 GB
- 500,000,000,000 B · 465.7 GiB
- 1 TB
- 1,000,000,000,000 B · 931.3 GiB
- 2 TB
- 2,000,000,000,000 B · 1,862.6 GiB
- 4 TB
- 4,000,000,000,000 B · 3,725.3 GiB
The right-hand column is what a system reporting in binary units will show, whether or not it labels them GiB. The shortfall on a 4 TB drive is about 275 units, which is more than the whole capacity of a drive people were buying fifteen years ago.
One rung up, where the gap reaches ten percent
Gigabytes to terabytes is where the decimal and binary ladders have drifted furthest apart, and where the 931 GB drive gets its number.
Open GB to TB →Gigabyte figures converted to exact byte counts, with the gibibyte reading alongside so an advertised capacity can be checked against what a system will report.
| Gigabytes | Bytes (decimal GB) | Same capacity in GiB |
|---|---|---|
| 0.5 GB | 500,000,000 | 0.47 |
| 1 GB | 1,000,000,000 | 0.93 |
| 2 GB | 2,000,000,000 | 1.86 |
| 4 GB | 4,000,000,000 | 3.73 |
| 8 GB | 8,000,000,000 | 7.45 |
| 16 GB | 16,000,000,000 | 14.90 |
| 32 GB | 32,000,000,000 | 29.80 |
| 64 GB | 64,000,000,000 | 59.60 |
| 256 GB | 256,000,000,000 | 238.42 |
| 500 GB | 500,000,000,000 | 465.66 |
| 1,000 GB | 1,000,000,000,000 | 931.32 |
Advertisement
The drive that appeared to lose 69 gigabytes
The most-searched question about this conversion is not really about conversion at all. Somebody buys a 1 TB drive, plugs it in, and is told they have 931 GB. The instinct is that something has been taken, and the usual suspects offered are formatting overhead, a recovery partition, or the manufacturer rounding in its own favour.
- Advertised
- 1 TB
- Actual bytes on the drive
- 1,000,000,000,000
- Divided by 1,073,741,824
- 931.32
- Reported as
- 931 GB
- Bytes actually missing
- none
- Cause
- a unit change, not a shortfall
Formatting overhead is real but small — a few gigabytes at most on a drive this size. The 69-unit difference is entirely the divisor. If the operating system printed GiB instead of GB the number would be identical and nobody would ask the question.
It is worth knowing which explanation is which, because they lead to different actions. A unit mismatch needs no action at all. Genuine overhead — a hidden recovery partition, a filesystem journal, reserved blocks — is separate, usually accounts for a few percent, and can sometimes be reclaimed.
Provisioning storage without arguing about units
When you size something, the useful discipline is to carry the byte count and convert only for display. A capacity plan that moves between decimal and binary figures at each step accumulates the 7.37 percent as a rounding error nobody can trace, and the error is always in the direction of assuming more space than exists.
Do
- Carry the exact byte count through a capacity calculation
- Say GiB when the figure came from dividing by 1,073,741,824
- Check whether a quoted capacity is the decimal or binary figure
- Budget headroom on top of the reported figure, not the advertised one
Don't
- Assume a reported gigabyte and an advertised gigabyte are the same unit
- Blame formatting for a shortfall of exactly 7.37 percent
- Convert back and forth between the scales inside one calculation
- Size a volume from the marketing figure and fill it to the stated number
The last one bites hardest in practice. If a plan says a volume holds 500 GB and the monitoring reports usage in GiB, then a dashboard showing 465 used means the volume is full, not 93 percent full. Alert thresholds set against the wrong unit fire late, which is exactly when they are least useful.
Every gigabytes value, worked out
79 common gigabytes figures each get their own page, with the answer, the arithmetic, what rounding costs, and the nearest real-world reference point on the scale.
Advertisement
Questions people ask
How many bytes are in 1 GB?
One billion bytes under the SI definition, so 8 GB is 8,000,000,000 bytes. The binary unit of roughly the same size is the gibibyte, GiB, which holds 1,073,741,824 bytes. The two differ by 7.37 percent, and both are in everyday use on different kinds of equipment.
Why does my 1 TB drive show as 931 GB?
Because the drive holds a trillion bytes and the operating system is dividing by 1,073,741,824 rather than a billion. That gives 931.32, which it then labels GB. No capacity is missing. If the same figure were labelled GiB, which is what it actually is, the number would look correct rather than short.
Is 1 GB 1,024 MB or 1,000 MB?
1,000 MB under the SI prefixes, which makes a gigabyte a billion bytes. The 1,024 figure belongs to the gibibyte, GiB, at 1,073,741,824 bytes. Both units exist and are correctly defined; the confusion comes from software using the binary quantity while printing the decimal name beside it.
Does formatting explain the missing gigabytes?
Only a small part of it. Filesystem structures and reserved blocks typically account for a few percent of a drive. A shortfall of exactly 7.37 percent is the decimal-to-binary difference, not overhead. You can tell them apart by checking whether the reported figure matches the capacity divided by 1,073,741,824.
Which figure should I use when provisioning storage?
Carry the byte count and convert only when displaying it. Mixing decimal and binary figures inside one capacity plan accumulates a 7.37 percent error that always points toward assuming more space than exists, and it surfaces at the worst moment, when a volume fills earlier than the plan said it would.
Sources
Where the constants and formulas on this page come from. Each line names the figure it backs.
The gibibyte is defined as 2^30 bytes, 1,073,741,824, and is a distinct unit from the decimal gigabyte of 10^9 bytes.
IEC 80000-13 Quantities and units — Part 13: Information science and technology — International Electrotechnical Commission
The SI prefix giga denotes a factor of 10^9 exactly, and SI prefixes are never used to denote powers of two.
The International System of Units (SI), 9th edition — BIPM, 2019
Related guides
Unit Converters
How Many Decimals to Keep When Converting Units
The factor is exact to nine digits. The measurement you typed is good to one. Only one of those two limits the answer, and it is not the factor.
August 19, 2026 · 9 min read
Unit Converters
Converting Temperature Differences: Why 10 °C of Change Is 18 °F, Not 50
A day that warms from 10 °C to 20 °C warms by 18 °F, not 50. The 32 belongs to temperatures — a difference never sees it.
August 16, 2026 · 9 min read
Dates & Time
Time and a Half: The Regular Rate Is Not Your Hourly Wage
Every explanation says multiply your hourly rate by 1.5. That is the wrong number the moment a bonus, a shift differential, or a second pay rate enters the week.
August 30, 2026 · 8 min read