Data Storage Converter

Q: Why does my 1 TB hard drive only show 931 GB?

Hard drive manufacturers use decimal gigabytes (1 GB = 1,000,000,000 bytes), while operating systems display binary gibibytes (1 GiB = 1,073,741,824 bytes) but often label them 'GB'. So a 1 TB drive contains 1,000,000,000,000 bytes, which equals 931.3 GiB. Both measurements are correct—they just use different base units. This ~7% difference increases with larger drives.

Q: What's the difference between KB and KiB?

KB (kilobyte) officially means 1,000 bytes under the SI decimal system, while KiB (kibibyte) means 1,024 bytes under the IEC binary system. Historically, 'KB' was used for 1,024 bytes in computing, which caused confusion. The IEC introduced KiB, MiB, GiB, etc. in 1998 to provide unambiguous binary units. However, adoption is inconsistent—Windows shows binary values labeled with decimal prefixes.

Q: Why are internet speeds in Mbps but downloads in MB/s?

Internet service providers advertise speeds in megabits per second (Mbps) because the larger numbers look more impressive. Computers measure file transfers in megabytes per second (MB/s). Since 1 byte = 8 bits, divide the advertised speed by 8 to get theoretical download speed. A 100 Mbps connection can theoretically download at 12.5 MB/s, though real-world speeds are typically 60-80% of this due to overhead.

Q: How do I convert Mbps to MB/s?

Divide Mbps by 8 to get MB/s. For example: 100 Mbps ÷ 8 = 12.5 MB/s. For quick mental math, divide by 10 for a conservative estimate (100 Mbps ≈ 10 MB/s). Remember: lowercase 'b' means bits, uppercase 'B' means bytes. This distinction is crucial when comparing speeds or estimating download times.

Q: Which units do cloud storage services use?

Cloud storage services (Google Drive, Dropbox, iCloud, OneDrive) typically use decimal units: 1 GB = 1,000,000,000 bytes. This matches what storage manufacturers use but differs from what your OS reports. When a service advertises 15 GB free, you'll get exactly 15,000,000,000 bytes, which your computer might display as approximately 13.97 GiB.

Q: What comes after terabyte and petabyte?

The sequence continues: exabyte (EB/EiB), zettabyte (ZB/ZiB), yottabyte (YB/YiB), ronnabyte (RB/RiB), and quettabyte (QB/QiB). The last two were added by the SI in 2022 to accommodate growing data needs. For perspective: global internet traffic is measured in zettabytes, and the total data in existence exceeds 100 zettabytes.

Convert between data storage units including bytes, kilobytes, megabytes, gigabytes, terabytes, and more.

Convert Data Storage

Value

From

Common Conversions

Note: KB/MB/GB use base 1000 (decimal), while KiB/MiB/GiB use base 1024 (binary).

Result

1,000

Megabytes (MB)

1 Gigabytes = 1,000 Megabytes

All Conversions

Bits (b)8,000,000,000

Bytes (B)1,000,000,000

Kilobytes (KB)1,000,000

Kibibytes (KiB)976,562.5

Megabytes (MB)1,000

Mebibytes (MiB)953.6743

Gigabytes (GB)1

Gibibytes (GiB)0.9313

Terabytes (TB)0.001

Tebibytes (TiB)0.0009

Petabytes (PB)1.0000e-6

Pebibytes (PiB)8.8818e-7

Kilobits (Kb)8,000,000

Megabits (Mb)8,000

Gigabits (Gb)8

Common File Sizes

Text file (1 page)2 KB

MP3 song (3 min)3 MB

HD Photo5 MB

HD Movie (1.5 hrs)4 GB

4K Movie (2 hrs)20 GB

Smartphone storage128 GB

Laptop SSD512 GB

External HDD2 TB

Decimal vs Binary

Decimal (SI)

1 KB = 1,000 B
1 MB = 1,000 KB
1 GB = 1,000 MB

Binary (IEC)

1 KiB = 1,024 B
1 MiB = 1,024 KiB
1 GiB = 1,024 MiB

What is Data Storage Conversion?

Data storage conversion transforms digital storage measurements between binary (IEC) and decimal (SI) systems. Understanding both is crucial for computing, networking, and purchasing storage devices.

Unit	Symbol	Binary (IEC)	Decimal (SI)
Kilo-	KB/KiB	1,024 bytes	1,000 bytes
Mega-	MB/MiB	1,048,576 bytes	1,000,000 bytes
Giga-	GB/GiB	1,073,741,824 bytes	1,000,000,000 bytes
Tera-	TB/TiB	1,099,511,627,776 bytes	1,000,000,000,000 bytes
Peta-	PB/PiB	1,125,899,906,842,624 bytes	10¹⁵ bytes

Key difference: Binary uses powers of 1,024 (2¹⁰), decimal uses powers of 1,000 (10³). This creates increasing disparity at larger scales.

Binary vs Decimal

1 GiB = 1,024 MiB = 1,073,741,824 bytes 1 GB = 1,000 MB = 1,000,000,000 bytes

Where:

GiB= Gibibyte (binary)
GB= Gigabyte (decimal)
MiB= Mebibyte (binary)
MB= Megabyte (decimal)

Bits vs. Bytes

The fundamental distinction in digital measurement is between bits (binary digits) and bytes (8 bits). This affects everything from storage to network speeds.

Concept	Bits	Bytes	Common Use
Unit symbol	b (lowercase)	B (uppercase)	Mb vs MB
Relationship	1 byte = 8 bits	1 bit = 0.125 bytes	Conversion
Network speed	100 Mbps	12.5 MB/s	Internet plans
File size	8 Mb	1 MB	Downloads
Storage	Rarely used	500 GB SSD	Hard drives

Common confusion: Internet speeds advertised in Mbps (megabits) vs download speeds shown in MB/s (megabytes). 100 Mbps ÷ 8 = 12.5 MB/s theoretical maximum.

Bits to Bytes

Bytes = Bits ÷ 8 MB/s = Mbps ÷ 8

Where:

b= Bits (lowercase)
B= Bytes (uppercase)
Mbps= Megabits per second
MB/s= Megabytes per second

Binary (IEC) Units

The IEC binary prefixes (established 1998) provide unambiguous terms for powers of 1,024, eliminating confusion with decimal prefixes.

Unit	Symbol	Bytes	Power
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

Usage: Operating systems (Windows, Linux, macOS) typically report storage in binary (GiB), though Windows labels it "GB" causing confusion.

Binary Conversions

1 TiB = 1,024 GiB = 1,048,576 MiB = 1,073,741,824 KiB

Where:

TiB= Tebibyte
GiB= Gibibyte
MiB= Mebibyte
KiB= Kibibyte

Decimal (SI) Units

SI decimal prefixes use powers of 1,000, consistent with scientific notation and metric standards. Storage manufacturers typically use decimal units.

Unit	Symbol	Bytes	Power
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	10¹⁸	10¹⁸

Storage marketing: A "1 TB" hard drive contains 1,000,000,000,000 bytes, which equals approximately 931 GiB as shown by your operating system.

Decimal Conversions

1 TB = 1,000 GB = 1,000,000 MB = 1,000,000,000 KB

Where:

TB= Terabyte (decimal)
GB= Gigabyte (decimal)
MB= Megabyte (decimal)
KB= Kilobyte (decimal)

Why Drives Show Less Space

The infamous "missing space" on hard drives results from the binary vs. decimal mismatch:

Marketed Size	Actual Bytes	OS Shows (GiB)	"Missing"
128 GB SSD	128,000,000,000	119.2 GiB	~7%
256 GB SSD	256,000,000,000	238.4 GiB	~7%
500 GB SSD	500,000,000,000	465.7 GiB	~7%
1 TB HDD	1,000,000,000,000	931.3 GiB	~7%
2 TB HDD	2,000,000,000,000	1,862.6 GiB	~7%
4 TB HDD	4,000,000,000,000	3,725.3 GiB	~7%

Note: Additional "missing" space is consumed by file system overhead, reserved blocks, and (in SSDs) over-provisioning for wear leveling.

Conversion Formula

GiB = GB × (1,000,000,000 ÷ 1,073,741,824) ≈ GB × 0.931

Where:

GB= Decimal gigabytes (marketed)
GiB= Binary gibibytes (OS display)

Network and Transfer Speeds

Network speeds are measured in bits per second, while file transfers display bytes per second. Understanding the relationship helps set realistic expectations.

Connection Type	Speed (bits)	Max Transfer (bytes)	1 GB Download
Dial-up modem	56 Kbps	7 KB/s	~40 hours
DSL	10 Mbps	1.25 MB/s	~13 minutes
Cable internet	100 Mbps	12.5 MB/s	~80 seconds
Fiber (common)	1 Gbps	125 MB/s	~8 seconds
Fiber (premium)	10 Gbps	1.25 GB/s	<1 second
USB 3.0	5 Gbps	625 MB/s	~1.6 seconds
USB 4.0	40 Gbps	5 GB/s	<0.2 seconds

Real-world: Actual speeds are typically 60-80% of theoretical maximum due to protocol overhead, latency, and network congestion.

Speed Conversion

MB/s = Mbps ÷ 8 Download time (s) = File size (MB) ÷ Speed (MB/s)

Where:

Mbps= Megabits per second
MB/s= Megabytes per second

Data Storage at Scale

Modern data storage spans an enormous range, from individual files to global data centers:

Size	Typical Content	Example
1 KB	Plain text	Half a page of text
1 MB	Documents, music	1 minute of MP3 audio
1 GB	Videos, games	~1 hour of HD video
1 TB	Large libraries	~500 hours of HD video
1 PB	Enterprise storage	~500 billion pages of text
1 EB	Data centers	~1 billion GB
1 ZB	Global internet	~1 trillion GB

Fun fact: Global internet traffic exceeded 4.8 zettabytes in 2022, and total data created annually now exceeds 100 zettabytes.

Worked Examples

Hard Drive Capacity Calculation

Problem:

A 2 TB external hard drive shows only 1.81 TB in Windows. Why, and what's the actual usable space in GiB?

Solution Steps:

1Marketed capacity: 2 TB = 2,000,000,000,000 bytes (decimal)
2Convert to GiB: 2,000,000,000,000 ÷ 1,073,741,824 = 1,862.6 GiB
3Windows displays GiB but labels it 'TB': 1,862.6 GiB ÷ 1,024 = 1.819 'TB'
4Additional space lost to file system: typically 1-5%

Result:

2 TB drive = 1,862.6 GiB ≈ 1.82 TiB displayed as '1.81 TB' in Windows

Download Time Calculation

Problem:

How long will it take to download a 4.7 GB movie on a 50 Mbps connection?

Solution Steps:

1Convert speed: 50 Mbps ÷ 8 = 6.25 MB/s
2File size: 4.7 GB = 4,700 MB
3Ideal time: 4,700 ÷ 6.25 = 752 seconds = 12.5 minutes
4Real-world estimate (70% efficiency): 752 ÷ 0.70 ≈ 18 minutes

Result:

Theoretical: 12.5 minutes; Realistic: ~15-20 minutes

Convert Between Binary and Decimal

Problem:

Your OS shows 476.8 GiB free on a 512 GB SSD. Is this correct?

Solution Steps:

1SSD marketed capacity: 512 GB = 512,000,000,000 bytes
2Convert to GiB: 512,000,000,000 ÷ 1,073,741,824 = 476.8 GiB
3This matches what the OS shows
4The drive is correctly reporting capacity; the difference is units, not missing space

Result:

Yes, 512 GB (decimal) = 476.8 GiB (binary). No space is 'missing.'

Tips & Best Practices

✓Divide storage marketing GB by 1.074 to get what your OS will show (approximate)
✓1 TB marketed ≈ 931 GiB displayed - expect about 7% less than advertised
✓Internet speed Mbps ÷ 8 = download speed MB/s (theoretical max)
✓Bits use lowercase 'b' (Mb, Gb), bytes use uppercase 'B' (MB, GB)
✓For RAM, always use binary (GiB) - RAM is manufactured in powers of 2
✓When comparing storage prices, convert to same units first (usually $/GB decimal)
✓Real download speeds are typically 60-80% of theoretical maximum

Frequently Asked Questions

Hard drive manufacturers use decimal gigabytes (1 GB = 1,000,000,000 bytes), while operating systems display binary gibibytes (1 GiB = 1,073,741,824 bytes) but often label them 'GB'. So a 1 TB drive contains 1,000,000,000,000 bytes, which equals 931.3 GiB. Both measurements are correct—they just use different base units. This ~7% difference increases with larger drives.

KB (kilobyte) officially means 1,000 bytes under the SI decimal system, while KiB (kibibyte) means 1,024 bytes under the IEC binary system. Historically, 'KB' was used for 1,024 bytes in computing, which caused confusion. The IEC introduced KiB, MiB, GiB, etc. in 1998 to provide unambiguous binary units. However, adoption is inconsistent—Windows shows binary values labeled with decimal prefixes.

Internet service providers advertise speeds in megabits per second (Mbps) because the larger numbers look more impressive. Computers measure file transfers in megabytes per second (MB/s). Since 1 byte = 8 bits, divide the advertised speed by 8 to get theoretical download speed. A 100 Mbps connection can theoretically download at 12.5 MB/s, though real-world speeds are typically 60-80% of this due to overhead.

Divide Mbps by 8 to get MB/s. For example: 100 Mbps ÷ 8 = 12.5 MB/s. For quick mental math, divide by 10 for a conservative estimate (100 Mbps ≈ 10 MB/s). Remember: lowercase 'b' means bits, uppercase 'B' means bytes. This distinction is crucial when comparing speeds or estimating download times.

Cloud storage services (Google Drive, Dropbox, iCloud, OneDrive) typically use decimal units: 1 GB = 1,000,000,000 bytes. This matches what storage manufacturers use but differs from what your OS reports. When a service advertises 15 GB free, you'll get exactly 15,000,000,000 bytes, which your computer might display as approximately 13.97 GiB.

The sequence continues: exabyte (EB/EiB), zettabyte (ZB/ZiB), yottabyte (YB/YiB), ronnabyte (RB/RiB), and quettabyte (QB/QiB). The last two were added by the SI in 2022 to accommodate growing data needs. For perspective: global internet traffic is measured in zettabytes, and the total data in existence exceeds 100 zettabytes.

Sources & References

IEC 80000-13: Binary Prefixes (2024)
NIST - Prefixes for Binary Multiples (2024)
SI Brochure - Bureau International des Poids et Mesures (2024)
IEEE Computer Society - Data Storage Standards (2024)

Last updated: 2026-01-22

Data Storage Converter

Convert Data Storage

All Conversions

Common File Sizes

Decimal vs Binary

What is Data Storage Conversion?

Binary vs Decimal

Bits vs. Bytes

Bits to Bytes

Binary (IEC) Units

Binary Conversions

Decimal (SI) Units

Decimal Conversions

Why Drives Show Less Space

Conversion Formula

Network and Transfer Speeds

Speed Conversion

Data Storage at Scale

Worked Examples

Hard Drive Capacity Calculation

Download Time Calculation

Convert Between Binary and Decimal

Tips & Best Practices

Frequently Asked Questions

Sources & References

Related Calculators

Speed

Length

Volume