Data Storage Converter | Size, Speed & Capacity

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

Advertised: 100 Mbps
Math: 100 ÷ 8 = 12.5
Reality: 12.5 MB/s

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. However, your Mac displays files in GiB. Your cloud drive might 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 (18x 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)

5 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 larger 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.

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.

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

About This Tool

Standards: We use IEC 80000-13 for binary units, SI for decimal, and IEEE 1541 for bits/bytes.

Accuracy: All calculations use precise integer math or floating point with high precision before rounding.

Privacy: No data is sent to any server. All calculations happen locally in your browser.