Data Storage Converter | Size, Speed & Capacity
Convert between 42+ digital storage units instantly. Understand the difference between decimal (GB) and binary (GiB) standards.
Result
Why your storage units confuse everyone
The #1 question we get is: "Why does my 1 TB drive show as 931 GB in Windows?" It is not a scam — it is a language problem.
- Hard drive manufacturers use Decimal (SI) units. For them, 1 TB = 1,000,000,000,000 bytes.
- Windows uses Binary (IEC) units (but often labels them wrong). For Windows, 1 TiB = 1,099,511,627,776 bytes.
Because binary units are larger, the number looks smaller. 1,000,000,000,000 ÷ 1,099,511,627,776 ≈ 0.909. That's where your "missing" 9% goes.
Decimal (SI) vs Binary (IEC) comparison
The gap widens as the file size gets larger. A kilobyte difference is tiny, but a petabyte difference is massive.
| Level | Decimal (base 1000) | Binary (base 1024) | Difference |
|---|---|---|---|
| KB / KiB | 1,000 bytes | 1,024 bytes | 2.4% |
| MB / MiB | 1,000,000 bytes | 1,048,576 bytes | 4.9% |
| GB / GiB | 10⁹ bytes | 1.074 × 10⁹ bytes | 7.4% |
| TB / TiB | 10¹² bytes | 1.100 × 10¹² bytes | 10.0% |
| PB / PiB | 10¹⁵ bytes | 1.126 × 10¹⁵ bytes | 12.6% |
Bits vs bytes: the ISP trap
This is the second most common confusion. ISPs advertise speed in megabits (Mbps), but you download files in megabytes (MB/s).
- The golden rule:
8 bits = 1 byte. To get your real download speed, divide the advertised speed by 8. - Example: 100 Mbps advertised →
100 ÷ 8 = 12.5→ 12.5 MB/s in practice.
Real-world applications
- 🎮 Gaming. Modern AAA games are 50–200 GB. A 1 TB SSD has about 931 GiB usable. After the OS (approx. 60 GiB), you can only fit about 5–10 major games.
- ☁️ Cloud subscriptions. 1 TB of iCloud storage is 1,000 GB decimal. Your Mac displays files in GiB, so your cloud drive may look "full" earlier than expected.
- 🎬 Video production. Shooting 4K? You burn through ~12 GB per minute. A 1-hour project is 720 GB. You need multiple TBs of storage.
- 🖥️ Sysadmins. Always plan servers in TiB. If you need 50 TB of usable space, buying five 10 TB drives isn't enough (yields ~45 TiB) — you need six.
Storage evolution
Capacity has doubled roughly every 18–24 months for 50 years.
- 1971: Floppy disk (8") = 80 KB
- 1987: 3.5" HD floppy = 1.44 MB (18× increase)
- 1995: CD-ROM = 700 MB (486 floppies!)
- 1997: DVD = 4.7 GB (~7 CDs)
- 2006: Blu-ray = 25 GB (~5 DVDs)
- Today: microSD card = 1.5 TB (1 million floppies in your fingernail)
Five mistakes everyone makes
- Confusing GB and GiB. They differ by 7.4%. Be precise.
- Mixing bits and bytes. 100 Mbps is not 100 MB/s.
- Assuming linear scaling. The gap between SI and IEC grows with size (KB = 2.4%, PB = 12.6%).
- Ignoring formatting overhead. A drive loses space to the file system index (tables of contents).
- RAID math. RAID 5 requires one full drive for parity. 5 drives = 4 drives worth of space.
Unit reference table
| Unit | Abbr. | Value (bytes) | Standard |
|---|---|---|---|
| Kilobyte | KB | 1,000 | SI (decimal) |
| Kibibyte | KiB | 1,024 | IEC (binary) |
| Megabyte | MB | 1,000,000 | SI |
| Mebibyte | MiB | 1,048,576 | IEC |
| Gigabyte | GB | 1,000,000,000 | SI |
| Gibibyte | GiB | 1,073,741,824 | IEC |
| Terabyte | TB | 10¹² | SI |
| Tebibyte | TiB | 1.099 × 10¹² | IEC |
Frequently asked questions
Why does my 1 TB drive show 931 GiB?
It's just math. 1 TB (decimal) equals roughly 0.909 TiB (binary). Windows displays the binary value but confusingly labels it "GB".
What is the difference between GB and GiB?
GB is 1,000,000,000 bytes. GiB is 1,073,741,824 bytes. GiB is the standard for computer memory and OS calculations.
How do I convert internet speed to download speed?
Divide by 8. Internet is sold in bits (Mbps); downloads happen in bytes (MB/s).
Is RAM measured in GB or GiB?
RAM is always binary (GiB), even if the sticker says "8 GB". An 8 GB stick is 8 GiB actual capacity.