Data Storage Converter
Type a number in the Enter Value field, choose your unit from the Select Storage Unit dropdown, and the results grid calculates equivalents across all 35 units — decimal (SI, base 1000) and binary (IEC, base 1024). Or pick any unit below to get its full conversion table.
Universal Storage Converter
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Fundamental Units
Decimal (SI) Units
Binary (IEC) Units
Decimal Bit Units
Binary Bit Units
How Data Storage Units Work
Every piece of digital data — a photo, a database record, an operating system kernel — is ultimately stored as a sequence of bits. A bit is the smallest possible unit of information: a single 0 or 1. On its own, a bit isn't particularly useful. Group eight bits together and you get a byte, which can represent a single character of text, a value from 0 to 255, or one sample of low-resolution audio.
From the byte, larger units scale upward in multiples. The question is which multiples — and that's where things get interesting.
In the decimal (SI) system, each step up multiplies by 1,000:
- 1 Kilobyte (KB) = 1,000 Bytes
- 1 Megabyte (MB) = 1,000 KB = 1,000,000 Bytes
- 1 Gigabyte (GB) = 1,000 MB = 1,000,000,000 Bytes
- 1 Terabyte (TB) = 1,000 GB = 1,000,000,000,000 Bytes
- 1 Petabyte (PB) = 1,000 TB = 1,000,000,000,000,000 Bytes
In the binary (IEC) system, each step up multiplies by 1,024 (which is 210):
- 1 Kibibyte (KiB) = 1,024 Bytes
- 1 Mebibyte (MiB) = 1,024 KiB = 1,048,576 Bytes
- 1 Gibibyte (GiB) = 1,024 MiB = 1,073,741,824 Bytes
- 1 Tebibyte (TiB) = 1,024 GiB = 1,099,511,627,776 Bytes
- 1 Pebibyte (PiB) = 1,024 TiB = 1,125,899,906,842,624 Bytes
The binary system exists because computers address memory in powers of 2. RAM chips, filesystem block allocations, and CPU cache lines all operate in binary multiples. The decimal system exists because humans count in base 10, and the International System of Units (SI) already had well-established metric prefixes (kilo, mega, giga). In 1998, the IEC introduced the binary prefixes (kibi, mebi, gibi) to eliminate ambiguity — but adoption has been slow, and both systems remain in active use today.
Complete Storage Unit Reference
The tables below list every standard storage unit in both the decimal (SI) and binary (IEC) systems. Use these as a quick lookup when planning capacity or interpreting spec sheets.
Decimal (SI) Storage Units
| Unit | Symbol | Equivalent in Bytes | Factor |
|---|---|---|---|
| Byte | B | 1 | 100 |
| Kilobyte | KB | 1,000 | 103 |
| Megabyte | MB | 1,000,000 | 106 |
| Gigabyte | GB | 1,000,000,000 | 109 |
| Terabyte | TB | 1,000,000,000,000 | 1012 |
| Petabyte | PB | 1,000,000,000,000,000 | 1015 |
| Exabyte | EB | 1,000,000,000,000,000,000 | 1018 |
| Zettabyte | ZB | 1,000,000,000,000,000,000,000 | 1021 |
| Yottabyte | YB | 1,000,000,000,000,000,000,000,000 | 1024 |
Binary (IEC) Storage Units
| Unit | Symbol | Equivalent in Bytes | Factor |
|---|---|---|---|
| Byte | B | 1 | 20 |
| Kibibyte | KiB | 1,024 | 210 |
| Mebibyte | MiB | 1,048,576 | 220 |
| Gibibyte | GiB | 1,073,741,824 | 230 |
| Tebibyte | TiB | 1,099,511,627,776 | 240 |
| Pebibyte | PiB | 1,125,899,906,842,624 | 250 |
| Exbibyte | EiB | 1,152,921,504,606,846,976 | 260 |
| Zebibyte | ZiB | 1,180,591,620,717,411,303,424 | 270 |
| Yobibyte | YiB | 1,208,925,819,614,629,174,706,176 | 280 |
Decimal vs Binary — The 1000 vs 1024 Problem
Decimal (SI) units use base 1000: 1 KB = 1,000 bytes, 1 MB = 1,000 KB. These are used by storage manufacturers and most operating systems when displaying drive capacity. Related: Convert Mbps Gbps and transfer speeds.
Binary (IEC) units use base 1024: 1 KiB = 1,024 bytes, 1 MiB = 1,024 KiB. These are used by file systems, RAM specifications, and when calculating actual data sizes. Learn more: calculate RAID overhead and usable capacity.
This difference explains why a "1 TB" drive shows as ~931 GB in your operating system — the drive uses decimal TB while the OS displays binary GiB. Understanding this distinction is crucial for accurate storage planning and capacity estimation. See also: StorageMath calculators.
This mismatch between decimal and binary is more than a trivia question — it causes real confusion every day. Here's why the two systems persist:
Why manufacturers use decimal (base 1000): Hard drive and SSD manufacturers label capacity using SI decimal units. A "1 TB" drive contains exactly 1,000,000,000,000 bytes. This aligns with the IEC standard and is technically correct. It also happens to produce larger-looking numbers on the box — but the primary reason is that the SI prefix system has been an international standard since 1960.
Why operating systems use binary (base 1024): Historically, operating systems reported file sizes in powers of 1,024 but labelled them with SI prefixes (KB, MB, GB). Windows still does this today. macOS switched to decimal display in OS X 10.6 Snow Leopard (2009). Linux utilities vary — ls -l shows bytes, df -h uses powers of 1,024 but labels them with SI prefixes by default, while df -H uses true decimal.
The real-world impact: Buy a 2 TB NVMe drive, plug it into a Windows PC, and the OS reports approximately 1.81 TB of usable space. You haven't lost data — the drive still holds 2,000,000,000,000 bytes. But Windows divides by 1,024 three times (to get "TB"), yielding 2,000,000,000,000 / 1,099,511,627,776 = 1.818 TB.
The percentage gap between decimal and binary labels grows at larger scales:
| Advertised (Decimal) | Actual Bytes | Displayed in OS (Binary) | Apparent "Loss" |
|---|---|---|---|
| 1 KB | 1,000 | 0.977 KiB | 2.3% |
| 1 MB | 1,000,000 | 0.954 MiB | 4.6% |
| 1 GB | 1,000,000,000 | 0.931 GiB | 6.9% |
| 1 TB | 1,000,000,000,000 | 0.909 TiB | 9.1% |
| 1 PB | 1,000,000,000,000,000 | 0.888 PiB | 11.2% |
| 1 EB | 1,000,000,000,000,000,000 | 0.867 EiB | 13.3% |
At the petabyte scale, you'd see an 11.2% discrepancy — for a 10 PB storage array, that's over 1.1 PB of "missing" space in your monitoring dashboard if it uses binary units. This is why enterprise storage engineers always clarify which unit system they're referencing.
Common Storage Conversion Examples
How many photos fit on a 256 GB SD card?
Assume a typical smartphone photo is about 5 MB (a 12 MP JPEG at high quality). A 256 GB card holds 256,000 MB in decimal terms.
Calculation: 256,000 MB / 5 MB per photo = 51,200 photos
In practice, the card's formatted capacity is slightly less (filesystem overhead), so expect roughly 50,000 photos. If you shoot RAW images at ~25 MB each, that number drops to about 10,000.
Convert 500 GB to TB — step by step
Using decimal (SI) units:
500 GB / 1,000 = 0.5 TB
Using binary (IEC) units:
500 GiB / 1,024 = 0.488 TiB
The answer depends on which system you're working in. If a colleague says "half a terabyte," they almost certainly mean 500 GB (decimal). If you're calculating RAID capacity in a storage controller that reports in TiB, use the binary conversion.
Why does my 1 TB SSD only show 931 GB?
Your drive physically stores 1,000,000,000,000 bytes (1 TB decimal). Your operating system divides by 1,024 three times to display the value in "GB":
1,000,000,000,000 / 1,024 / 1,024 / 1,024 = 931.32 GiB
No storage was lost. The drive is delivering exactly what was advertised — the label just uses a different counting system than the OS display. Additionally, the drive firmware reserves a small percentage (typically 5-7% on SSDs) for over-provisioning, wear leveling, and bad block replacement, which further reduces user-visible capacity.
How much space does a full iPhone backup take?
A typical 128 GB iPhone that's 80% full contains about 102 GB of data. An uncompressed backup is roughly the same size. Compressed (as iCloud and iTunes do), expect around 60-80 GB depending on how much of your data is already compressed media (photos and videos don't compress much further).
Calculation: 128 GB x 0.80 usage x 0.70 compression ratio = ~72 GB backup size
Storage Units in the Real World
Understanding what typical files actually consume helps you plan storage purchases and estimate how long a drive will last. Here's a practical reference based on common file types:
| File Type | Typical Size | Files per 1 TB |
|---|---|---|
| Plain text email | ~20 KB | 50,000,000 |
| Word document (10 pages) | ~50 KB | 20,000,000 |
| Smartphone photo (JPEG, 12 MP) | ~5 MB | 200,000 |
| RAW photo (24 MP) | ~25 MB | 40,000 |
| MP3 song (4 min, 320 kbps) | ~10 MB | 100,000 |
| FLAC album (10 tracks) | ~500 MB | 2,000 |
| 1080p movie (H.264, 2 hours) | ~5 GB | 200 |
| 4K movie (HEVC, 2 hours) | ~50 GB | 20 |
| AAA video game | ~80 GB | 12 |
| Windows 11 installation | ~27 GB | 37 |
| Full macOS installation | ~13 GB | 76 |
| Virtual machine (dev environment) | ~40 GB | 25 |
A few rules of thumb for capacity planning:
- 256 GB is adequate for a lightweight laptop — OS, productivity apps, and cloud-synced files.
- 512 GB - 1 TB suits most users who store a moderate photo library, a few games, and local media.
- 2-4 TB is the sweet spot for content creators working with video, large RAW photo libraries, or multiple virtual machines.
- 8+ TB is typical for NAS devices, media servers, or professional video production where 4K/8K footage accumulates rapidly.
When buying external storage, remember that advertised capacity uses decimal units. A "4 TB" external drive gives you 4,000,000,000,000 bytes — which your computer displays as roughly 3.63 TiB. Factor this into your planning, especially when budgeting for backup drives that need to mirror an existing volume.