Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →SSD manufacturers normally advertise capacity in decimal units: GB means 1,000,000,000 bytes and TB means 1,000,000,000,000 bytes. TiB and GiB are binary units: 1 TiB is 1,099,511,627,776 bytes and 1 GiB is 1,073,741,824 bytes. An operating system or application may count the same bytes in binary while displaying a familiar-looking decimal label, so a drive sold as 1 TB can appear as about 0.909 TiB or 931 GiB without any storage being missing.
The unit system explains only part of a capacity difference. Partition tables, formatting, reserved areas and other device or software details can reduce the space available to files, so diagnose those separately from the TB-to-TiB conversion.
As an Amazon Associate I earn from qualifying purchases.
The four units at a glance
| Unit | Full name | Number system | Exact bytes | Where you commonly encounter it |
|---|---|---|---|---|
| GB | Gigabyte | Decimal (base 10) | 1,000,000,000 (109) | SSD packaging, product data sheets and other SI-based capacity labels |
| GiB | Gibibyte | Binary (base 2) | 1,073,741,824 (230) | Applications and operating-system tools that use IEC binary prefixes |
| TB | Terabyte | Decimal (base 10) | 1,000,000,000,000 (1012) | SSD packaging and manufacturer capacity ratings |
| TiB | Tebibyte | Binary (base 2) | 1,099,511,627,776 (240) | Binary-capacity reports and technical documentation |
GB and TB advance by powers of 1,000: 1 TB equals exactly 1,000 GB. GiB and TiB advance by powers of 1,024: 1 TiB equals exactly 1,024 GiB. They are different ways to describe a byte count, not different kinds of memory chips.
Why the prefixes are different
Decimal prefixes such as kilo-, mega-, giga- and tera- belong to the International System of Units (SI). Binary quantities were historically often described with the same names even though software was calculating powers of two. To remove that ambiguity, the International Electrotechnical Commission approved the prefixes kibi, mebi, gibi and tebi in December 1998. The National Institute of Standards and Technology (NIST) binary-prefix reference documents the definitions and byte values.
#1 Best Overall
- MEET THE NEXT GEN: Consider this a cheat code; Our Samsung 990 PRO Gen4 SSD helps you reach near max performance with lightning-fast speeds; Whether you’re a hardcore gamer or a tech guru, you’ll get power efficiency built for the final boss
- REACH THE NEXT LEVEL: Gen4 steps up with faster transfer speeds and high-performance bandwidth; With a more than 55% improvement in random performance compared to 980 PRO, it’s here for heavy computing and faster loading
- THE FASTEST SSD FROM THE WORLD'S FLASH MEMORY BRAND: The speed you need for any occasion; With read and write speeds up to 7450/6900 MB/s you’ll reach near max performance of PCIe 4.0 powering through for any use
- PLAY WITHOUT LIMITS: Give yourself some space with storage capacities from 1TB to 4TB; Sync all your saves and reign supreme in gaming, video editing, data analysis and more
- IT’S A POWER MOVE: Save the power for your performance; Get power efficiency all while experiencing up to 50% improved performance per watt over the 980 PRO; It makes every move more effective with less consumption
“It is important to recognize that the new prefixes for binary multiples are not part of the International System of Units (SI), the modern metric system.”
That distinction matters because the numerical gap grows as capacities get larger. A decimal gigabyte is about 6.87% smaller than a gibibyte, while a decimal terabyte is about 9.05% smaller than a tebibyte. The physical drive has the same number of bytes regardless of which unit is printed beside the number.
How to convert TB and GB to TiB and GiB
Start with the byte count, then divide by the size of the target unit. These formulas avoid ambiguity:
Free tools Windows power users keep installed
One-click scans. No signup required.
GiB = bytes ÷ 1,073,741,824TiB = bytes ÷ 1,099,511,627,776GB = bytes ÷ 1,000,000,000TB = bytes ÷ 1,000,000,000,000
For a drive marketed in decimal units, convenient direct conversions are:
1 TB = 0.9094947 TiB(approximately 0.909 TiB).1 TB = 931.3226 GiB(approximately 931 GiB).1 GB = 0.9313226 GiB.1 GiB = 1.073741824 GB.1 TiB = 1.099511627776 TB.
The values above are mathematical conversions of the same bytes. They do not imply that a manufacturer supplied fewer NAND cells or that an operating system deleted data.
Common SSD capacities in binary units
| Advertised capacity | Decimal bytes | Equivalent TiB | Equivalent GiB |
|---|---|---|---|
| 250 GB | 250,000,000,000 | 0.227 TiB | 232.83 GiB |
| 500 GB | 500,000,000,000 | 0.455 TiB | 465.66 GiB |
| 1 TB | 1,000,000,000,000 | 0.909 TiB | 931.32 GiB |
| 2 TB | 2,000,000,000,000 | 1.819 TiB | 1,862.65 GiB |
| 4 TB | 4,000,000,000,000 | 3.638 TiB | 3,725.29 GiB |
| 100 TB | 100,000,000,000,000 | 90.949 TiB | 93,132.26 GiB |
These are raw conversions before a partition is created or a file system is formatted. A tool that rounds to whole numbers may show 931, 1,862 or 3,725, so small differences in the last digit are normally rounding rather than a separate capacity standard. IBM gives the same scale effect in its storage documentation, showing 100 TB as about 90.94 TiB.
What SSD manufacturers mean by “1 TB”
Storage manufacturers commonly use decimal units on product packaging and specifications. The Seagate capacity-measurement guidance describes decimal capacity as the storage-industry standard and explains why a 1 TB drive may appear as roughly 931 in a binary-counting display. A separate explanation from Verbatim also covers SSD capacity labels and the difference between decimal product ratings and binary-style reporting.
Rank #2
- THE SSD ALL-STAR: The latest 870 EVO has indisputable performance, reliability and compatibility built upon Samsung's pioneering technology.Computer Platform:PC.Encryption : Class 0 (AES 256) TCG/Opal v2.0, MS eDrive (IEEE1667), Environmental Specs - Shock : 1,500 G & 0.5 ms (Half sine).
- EXCELLENCE IN PERFORMANCE: Enjoy professional level SSD performance with 870 EVO, which maximizes the SATA interface limit to 560/530 MB/s sequential speeds, Accelerates write speeds and maintains long term high performance with a larger variable buffer
- INDUSTRY DEFINING RELIABILITY: Meet the demands of every task from everyday computing to 8K video processing, with up to 2,400 TBW
- MORE COMPATIBLE THAN EVER: 870 EVO has been compatibility tested for major host systems and applications, including chipsets, motherboards, NAS, and video recording devices. Interface- SATA 6GB/s, compatible with SATA 3GB/s and SATA 1.5GB/s interfaces
Therefore, “1 TB SSD” means the manufacturer is promising a decimal byte count around 1,000,000,000,000 bytes, subject to the model’s published specifications. It does not mean the drive will display the number 1,000 in every operating-system window. To compare two SSDs, compare their decimal byte capacities on their data sheets; do not compare one product’s TB label with another tool’s TiB figure as though they were the same unit.
Why a 1 TB SSD can show about 931
- The manufacturer defines the label using decimal units: 1 TB = 1,000,000,000,000 bytes.
- The software counts in binary units and divides by 1,073,741,824 bytes per GiB.
- The result is 931.3226 GiB, which may be rounded to 931.
- If the interface writes “GB” instead of “GiB,” the label can look inconsistent even though the calculation is correct.
Seagate’s example uses the familiar wording “about 931 gigabytes (GB)” for this situation. Technically, when the divisor is 230, the unambiguous unit is GiB; the software’s displayed suffix determines how clearly the result is communicated.
How operating systems and applications display storage
There is no single rule for every operating system, release or screen. Some tools use SI units, some use IEC binary units, and some older or compatibility-oriented interfaces have displayed a decimal-looking label for a binary calculation. The label, the documentation for that particular tool and the underlying byte count all matter.
GNOME System Monitor documentation explicitly documents IEC labels such as KiB, MiB, GiB and TiB for memory and disk statistics, while noting that decimal sizes are common on hard-drive packaging. In such a display, a 1.0 TB device is shown as about 0.909 TiB before formatting and partition overhead.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Seagate discusses historical Windows and Mac interfaces, but that guidance does not establish the behavior of every current release or every storage screen. Do not assume that all Windows, macOS or Linux utilities use one convention. Instead, read the suffix shown by the exact utility:
- GB or TB used with powers of 1,000: the value is decimal.
- GiB or TiB: the value is explicitly binary.
- GB or TB with no documented basis: treat the label as ambiguous and verify the tool’s documentation or compare its value with the known byte count.
Two panels on the same computer can legitimately disagree if one reports decimal bytes and another reports binary units. Rounding can add another small difference.
Reading a capacity screen accurately
First identify whether the screen describes the entire physical device, a partition, a mounted volume or only free space. Then record the exact number and suffix. “931 GB free,” “931 GB total,” and “931 GiB for the physical disk” are different statements. A file manager may show a volume while a disk-management utility shows the whole device, so switching tools can change the apparent capacity even when no bytes have changed.
Rank #3
- HUGE SPEED BOOST: Get random read/write speeds that are 40%/55% faster than 980 PRO; Experience up to 1400K/1550K IOPS, while sequential read/write speeds up to 7,450/6,900 MB/s reach near the max performance of PCIe 4.0*
- BREAKTHROUGH POWER EFFICIENCY: Use less power and get more performance; Enjoy up to 50% improved performance per watt over 980 PRO, plus optimal power efficiency with max PCIe 4.0 performance**
- SMART THERMAL CONTROL: Samsung's own nickel-coated controller delivers effective thermal control; With its slim size, 990 PRO is a perfect fit for desktops and laptops that meet the PCI-SIG D8 standard***
- THE CHAMPION MAKER: Up to 65% improvement in random performance enables faster loads for an ultimate gaming experience on PS5 and DirectStorage PC games****
- SAMSUNG MAGICIAN SOFTWARE: Get the most out of your SSD with Samsung Magician's advanced yet intuitive optimization tools; Monitor drive health, protect valuable data, and receive important updates for your 990 PRO
If a screen uses only GB or TB, do not infer the base from the letters alone. Compare the value with the known decimal byte count or consult that utility’s documentation. A value near 931 for a 1 TB device indicates a binary divisor, but the clearest report is still “about 931 GiB” or the exact byte count.
Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallCapacity conversion is not the same as usable space
Unit conversion explains why 1,000,000,000,000 bytes becomes about 931 GiB. It does not explain every byte that is unavailable for files after installation. Seagate notes that several factors can affect reported capacity. Depending on the device and software, the user-visible figure can also reflect:
- Partition tables and unallocated space.
- File-system metadata and formatting overhead.
- Recovery partitions or other vendor-created partitions.
- Reserved or over-provisioned areas used by the storage controller.
- Different rounding rules in management tools.
- Software that reports a volume rather than the whole physical device.
The supplied sources do not quantify these effects for a particular SSD model, so there is no universal “formatting deduction” to subtract from every drive. A new drive can be healthy while its formatted volume is smaller than the raw decimal-to-binary conversion.
Separating the two parts of the difference
Think of the result in two stages. Stage one is arithmetic: convert the manufacturer’s decimal bytes into the unit used by the display. Stage two is layout: account for partitions, formatting, reserved capacity and whether the tool is showing a volume or the whole disk. If the physical disk’s raw byte count matches the specification but a volume is smaller, the discrepancy is in stage two. If the raw byte count itself is implausible, investigate the device or connection.
A reliable way to check a capacity discrepancy
- Record the advertised unit and byte count. Use the manufacturer’s specification, noting whether it says GB/TB and whether the figure is a decimal capacity.
- Identify what the operating-system tool is measuring. Is it the physical disk, one partition, a mounted volume or free space? Record the exact suffix, such as GB, TB, GiB or TiB.
- Convert the raw byte count into the displayed unit. Divide by 1,000,000,000 for GB, 1,000,000,000,000 for TB, 1,073,741,824 for GiB or 1,099,511,627,776 for TiB.
- Compare like with like. Compare raw physical-device bytes with raw physical-device bytes, or compare a formatted volume with another formatted volume. Do not compare a whole-disk specification with a single partition.
- Inspect the layout if the remaining gap is larger than the unit conversion. Look for unallocated space, recovery partitions, formatting overhead and reserved areas. The conversion should account for the expected decimal-versus-binary difference; the layout explains additional reductions.
- Check health only after the arithmetic and layout are understood. A capacity label by itself is not evidence of a defective SSD. Investigate warranty or diagnostic issues when the device reports an implausible byte count, disappears, or produces read/write errors—not merely because 1 TB is displayed as about 931 GiB.
Worked comparisons for planning
Suppose a backup program reports 465.66 GiB of source data. That is the binary expression of approximately 500,000,000,000 bytes, so a 500 GB decimal device has the corresponding raw capacity. The numbers should not be compared as 465 versus 500 without identifying their bases. Likewise, a 2 TB SSD has twice the decimal bytes of a 1 TB SSD, while a binary display reports approximately 1.819 TiB versus 0.909 TiB.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →For a larger archive, 100 TB is about 90.94 TiB, not 100 TiB. The difference is the same unit conversion seen at smaller sizes, but the numerical gap is more noticeable because the capacity is larger. Keep the byte count in planning worksheets so that a change of display unit does not look like a change in storage.
Choosing the right unit for common tasks
Shopping for an SSD
Use the manufacturer’s decimal TB or GB rating when comparing products. A 2 TB model is twice the advertised decimal capacity of a 1 TB model, even though a binary-capacity utility will show approximately 1.819 TiB and 0.909 TiB respectively. Check the interface, physical form factor and platform compatibility separately; changing the unit convention does not make an incompatible SSD fit or work.
Rank #4
- Upgrade your laptop or desktop computer and feel the difference with super-fast OS boot times and application loads
- Exceptional performance offering up to 535MB/s seq. Read and 500MB/s seq. Write speeds
- Superior performance as compared to traditional hard drives (HDD)
- Ultra-low power consumption
- Backwards compatible with SATA II 3GB/sec
Planning a disk image or backup
Check the backup software’s unit convention before estimating destination space. If the source utility reports 931 GiB and the destination specification is in decimal TB, convert the source byte count rather than assuming the two numbers are directly comparable. Leave additional room for versions, metadata and temporary files because raw capacity and available free space are different quantities.
Writing technical documentation
State both the unit and, when useful, the byte multiplier: for example, “1 TB (1012 bytes)” or “1 TiB (240 bytes).” This prevents readers from interpreting a decimal product rating as a binary operating-system measurement. If a tool uses an ambiguous GB label, document the tool and the conversion method alongside the number.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsCommunicating a storage problem
Report the physical device’s advertised capacity, the utility name, the exact displayed suffix and whether the value refers to the whole disk or a partition. “The 1 TB SSD shows 931 GiB for the physical disk” is actionable; “the drive is missing 69 GB” mixes unit systems and may send troubleshooting in the wrong direction.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Common mistakes and their fixes
| Mistake | Why it causes confusion | Better practice |
|---|---|---|
| Calling every 931 figure “931 GB” | The calculation may actually be in GiB, despite a legacy or simplified label. | Use the suffix the tool documents, or describe the byte count and say “about 931 GiB.” |
| Assuming 1 TB equals 1,024 GB | That combines a decimal prefix (TB) with a binary multiplier (1,024). | Use 1 TB = 1,000 GB, or use 1 TiB = 1,024 GiB. |
| Blaming formatting for the entire difference | The initial drop from 1 TB to about 931 GiB is already explained by the unit bases. | Convert the raw bytes first, then inspect partitions and file-system overhead. |
| Comparing a volume with the product label | A volume can exclude recovery, reserved or unallocated areas. | Compare the physical disk’s raw capacity with the specification before examining volumes. |
| Assuming every operating-system screen follows one standard | Different tools and releases can choose different units or labels. | Check the exact interface’s documentation and record its suffix. |
| Using rounded numbers in a capacity plan | Rounding can hide whether two values are actually equivalent. | Keep the byte count or several decimal places until the final presentation. |
Which unit should you use?
Use GB and TB when discussing manufacturer-rated SSD capacity, network transfer specifications and other decimal quantities. Use GiB and TiB when a program explicitly reports powers of two. Neither system is more correct in every context: the important part is naming the system and keeping the byte multiplier attached to the number.
For the specific case that causes most questions, a decimal 1 TB SSD contains 1,000,000,000,000 bytes. Expressed in binary units, those same bytes equal approximately 0.909 TiB or 931.32 GiB. Any further reduction in the space available to files must be explained by the disk layout, formatting, reserved capacity or software behavior—not by a change in the bytes physically present.
Frequently Asked Questions
Why does my 1 TB SSD show only about 931 GB?
The drive has 1,000,000,000,000 decimal bytes. Dividing that same byte count by 1,073,741,824 bytes per GiB gives 931.3226 GiB, usually rounded to 931. The display may say GB even though the calculation is binary.
Is 1 TB the same as 1 TiB?
No. TB is decimal and equals 1,000,000,000,000 bytes. TiB is binary and equals 1,099,511,627,776 bytes. A decimal 1 TB contains about 0.909 TiB.
Best Value
- THE SSD ALL-STAR: The latest 870 EVO has indisputable performance, reliability and compatibility built upon Samsung's pioneering technology. S.M.A.R.T. Support: Yes
- EXCELLENCE IN PERFORMANCE: Enjoy professional level SSD performance which maximizes the SATA interface limit to 560 530 MB/s sequential speeds,* accelerates write speeds and maintains long term high performance with a larger variable buffer, Designed for gamers and professionals to handle heavy workloads of high-end PCs, workstations and NAS
- INDUSTRY-DEFINING RELIABILITY: Meet the demands of every task — from everyday computing to 8K video processing, with up to 600 TBW** under a 5-year limited warranty***
- MORE COMPATIBLE THAN EVER: The 870 EVO has been compatibility tested**** for major host systems and applications, including chipsets, motherboards, NAS, and video recording devices
- UPGRADE WITH EASE: Using the 870 EVO SSD is as simple as plugging it into the standard 2.5 inch SATA form factor on your desktop PC or laptop; The renewed migration software takes care of the rest
Is 1 TB equal to 1,024 GB?
No. 1 TB equals exactly 1,000 GB because both are decimal units. The 1,024 relationship applies to 1 TiB and 1,024 GiB.
Are SSD manufacturers using the wrong units?
No. Decimal GB and TB are the standard capacity units used on storage packaging. The apparent reduction usually occurs when software expresses the same bytes with binary divisors or when a screen reports a partition instead of the whole disk.
Does formatting remove the missing 69 GB from a 1 TB drive?
No. The initial change from 1 TB to about 931 GiB is unit conversion. Partition tables, file-system metadata, recovery partitions, reserved areas and unallocated space can cause additional reductions, but there is no universal formatting deduction.
Why do two tools on the same computer show different capacities?
They may use different bases, labels or rounding rules, or one may show the physical disk while another shows a partition, mounted volume or free space. Check the exact suffix and what each tool measures.
Which unit should I use when comparing SSDs?
Compare the manufacturer’s decimal GB or TB byte capacities on the specifications. Then convert to GiB or TiB only when matching a particular operating-system or application display.
When should a capacity difference suggest a hardware problem?
A 1 TB label appearing as about 931 GiB is expected. Investigate further when the raw physical-device byte count is implausible, the drive disappears, or read/write errors occur after you have checked the unit basis and disk layout.
The Bottom Line
TB and GB are decimal; TiB and GiB are binary. A 1 TB SSD contains 1,000,000,000,000 bytes, which is approximately 0.909 TiB or 931.32 GiB. Check the exact unit, suffix and object being measured before treating a smaller number as lost storage.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
