Data Size Converter

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Data Size Converter

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Convert between data size units (KB, MB, GB, TB, KiB, MiB, GiB). Calculate transfer times and compare storage capacity for different media.

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Data Size Converter

Convert between bytes, kilobytes, megabytes, gigabytes, terabytes and binary units

120 ZB

Data created globally in 2023 (IDC)

1,024

Bytes in a Kibibyte (KiB), binary standard

100 Gbps

Speed of modern backbone internet connections

3.5"

Width of floppy disk — held only 1.44 MB

What Is Data Size?

Data size measures the amount of digital information stored or transmitted. The most fundamental unit is the bit (binary digit: 0 or 1). Eight bits form one byte, the basic addressable unit of computer memory.

There are two competing systems for expressing data sizes — and confusion between them causes one of the most common tech frustrations: why a hard drive appears smaller in Windows than on the box.

Decimal (SI) system: Used by storage manufacturers. Prefixes follow the International System of Units — kilo = 1,000, mega = 1,000,000. A manufacturer's "1 TB" hard drive contains exactly 1,000,000,000,000 bytes.

Binary (IEC) system: Used by operating systems. Prefixes are powers of 2 — kibi = 1,024, mebi = 1,048,576. Windows reports storage in GiB but labels them "GB", causing the apparent size discrepancy.

Everyday examples: a 4K video is ~50 GB/hour; an MP3 song is ~3–5 MB; a high-resolution photo is ~3–8 MB; a Blu-ray disc holds 50 GB; a modern smartphone ships with 128–512 GB of storage.

Key Facts

▸1 byte = 8 bits — the smallest addressable unit of memory
▸Decimal KB = 1,000 bytes; Binary KiB = 1,024 bytes (2.4% difference)
▸Hard drives use decimal sizing (why they appear smaller in Windows)
▸RAM uses binary — 8 "GB" RAM shows as ~7.45 GiB in OS tools

Formulas & Conversions

Decimal (SI)

1 KB = 1,000 bytes

1 MB = 1,000,000 bytes

1 GB = 10⁹ bytes

1 TB = 10¹² bytes

Binary (IEC)

1 KiB = 1,024 bytes

1 MiB = 1,048,576 bytes

1 GiB = 2³⁰ bytes

1 TiB = 2⁴⁰ bytes

Transfer Time

Time (sec) =

File Size (bits)

Speed (bps)

1 byte = 8 bits

Decimal vs Binary Comparison

Unit	Decimal (SI)	Binary (IEC)	Difference (%)
Kilo	1 KB = 1,000 bytes	1 KiB = 1,024 bytes	2.4%
Mega	1 MB = 1,000,000 bytes	1 MiB = 1,048,576 bytes	4.86%
Giga	1 GB = 10⁹ bytes	1 GiB = 2³⁰ bytes	7.37%
Tera	1 TB = 10¹² bytes	1 TiB = 2⁴⁰ bytes	9.95%
Peta	1 PB = 10¹⁵ bytes	1 PiB = 2⁵⁰ bytes	12.59%

History of Data Storage

1956

IBM 305 RAMAC — first commercial hard disk (5 MB, the size of two refrigerators; leased for $3,200/month)

1980

IBM PC launches with 320 KB floppy disk drive; popularizes KB/MB units in consumer computing

1998

IEC introduces KiB/MiB/GiB notation (IEC 80000-13) to formally distinguish binary from decimal prefixes

2001

First 1 GB USB flash drive released by Trek Technology at a retail price of ~$350

2012

US NIST officially adopts IEC binary prefixes in formal scientific publications (SP 330)

2023

World creates 120 zettabytes of data; 100 GB storage costs under $3 (50 million× cheaper than 1956)

Research & Standards

IDC Data Age 2025 Report

120 zettabytes of data created in 2023; 5x growth projected by 2025

Visit IDC Data Age 2025 Report →

IEC 80000-13:2021 Standard

Official international definition of KiB, MiB, GiB binary notation to prevent ambiguity

Visit IEC 80000-13:2021 Standard →

NIST SI Guide (SP 330)

US National Institute of Standards adoption of binary prefixes for data measurement

Visit NIST SI Guide (SP 330) →

Myths & Facts

Myth

My 1TB hard drive is broken — Windows shows only 931 GB

Fact

Drive manufacturers use decimal TB (10¹² bytes), but Windows shows binary GiB. 1 TB = 931.3 GiB — your drive is perfectly fine

Myth

1 kilobyte is always 1,024 bytes

Fact

Since the 1998 IEC standard: 1 KB = 1,000 bytes (decimal). The old 1,024-byte unit is now correctly called 1 KiB (kibibyte)

Myth

Internet speed in Mbps and file size in MB are the same thing

Fact

Internet speeds are in MEGABITS per second. A 100 Mbps connection downloads only 12.5 MB/sec — divide by 8, since 1 byte = 8 bits

Myth

Storage is storage — all gigabytes are equal

Fact

Hard drives (decimal), RAM (binary), and SSDs may use different sizing conventions. Always check whether specs use GB (decimal) or GiB (binary)

Frequently Asked Questions

What is the difference between KB and KiB?▾

KB (kilobyte) = 1,000 bytes in the decimal SI system. KiB (kibibyte) = 1,024 bytes in the binary IEC system. The IEC introduced the KiB notation in 1998 to eliminate the century-old ambiguity.

How many bytes are in a gigabyte?▾

In decimal (SI): 1 GB = 1,000,000,000 bytes (10⁹). In binary (IEC): 1 GiB = 1,073,741,824 bytes (2³⁰). The difference is about 7.4%.

Why does my hard drive show less space than advertised?▾

Drive manufacturers measure in decimal GB (10⁹ bytes), while Windows reports in binary GiB (2³⁰ bytes) but calls them GB. A 1 TB drive = 931.3 GiB — nothing is missing.

How do I calculate file transfer time?▾

Transfer time (seconds) = File size in bits ÷ Connection speed in bps. Remember: 1 byte = 8 bits. For a 100 MB file over 100 Mbps: (100 × 8) ÷ 100 = 8 seconds.

What is a zettabyte?▾

1 zettabyte = 10²¹ bytes = 1,000 exabytes = 1,000,000 petabytes. The entire internet traffic per year is measured in zettabytes. IDC estimated 120 ZB of data was created in 2023.

How many MB is a GB?▾

1 GB = 1,000 MB (decimal/SI). 1 GiB = 1,024 MiB (binary/IEC). The decimal definition is used by storage manufacturers; the binary by most operating systems.

What is the difference between Mbps and MBps?▾

Mbps = Megabits per second (lowercase b). MBps = Megabytes per second (uppercase B). Since 1 byte = 8 bits, 100 Mbps = 12.5 MBps. Always check the notation in network specs.

How many songs fit in 1 GB?▾

At typical 128 kbps MP3 quality (~1 MB/min), a 4-minute song ≈ 4 MB. So 1 GB ≈ 250 songs. At 320 kbps (high quality), 1 GB ≈ 100 songs.

What is the largest unit of data storage?▾

Commonly used: yottabyte (YB, 10²⁴). Beyond that: ronnabyte (10²⁷) and quettabyte (10³⁰) were officially added by BIPM in 2022. The yobibyte (YiB, 2⁸⁰) is the binary equivalent.

Why does Windows show different sizes than Mac for the same drive?▾

Older versions of Windows showed storage in GiB but labeled it GB. macOS switched in 2009 to use decimal GB matching drive specs. A file both systems show is the same size — only the label convention differs.

What is the IEC standard for data units?▾

IEC 80000-13:2021 defines binary prefixes: kibi (Ki, 2¹⁰), mebi (Mi, 2²⁰), gibi (Gi, 2³⁰), tebi (Ti, 2⁴⁰), pebi (Pi, 2⁵⁰), exbi (Ei, 2⁶⁰), zebi (Zi, 2⁷⁰), and yobi (Yi, 2⁸⁰).

How do I convert bits to bytes?▾

Divide bits by 8 to get bytes. Multiply bytes by 8 to get bits. Example: 1,000 bits = 125 bytes. A 1 Mbps network speed = 0.125 MB/s download speed.

References

IEC 80000-13:2021 — Quantities and units, Part 13: Information science and technology. International Electrotechnical Commission. iec.ch
NIST Special Publication 330 (2019) — The International System of Units (SI). US National Institute of Standards and Technology. nist.gov
IDC Global DataSphere Report 2023 — Data Age 2025: The Digitization of the World. International Data Corporation. idc.com
IEEE Computer Society Standards — Definitions of binary and decimal storage units and their prefixes. ieee.org
ISO/IEC 80000 — International standard covering quantities, units and their symbols for all fields of science and technology. iso.org

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Data Size Converter

Convert between data storage units instantly. Free converter for bytes, KB, MB, GB, TB, and PB with binary (1024) and decimal (1000) calculations for files.

Data Size Converter — Answer & Method

Convert between data storage units (bytes, KB, MB, GB, TB).

Formula: Data Conversion

1 KB = 1024 bytes (binary) or 1000 bytes (decimal)

B = Bytes (B)

Example Calculation

1 GB = 1,024 MB = 1,048,576 KB (binary).

Important limitation

Check the result against your specific circumstances before making a decision.

Key Facts

IEC binary prefixes: KiB = 1024 bytes, MiB = 1024 KiB.
SI decimal prefixes: KB = 1000 bytes, MB = 1000 KB.

Sources & Validation

IEC 80000-13

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Key Takeaways

✓Hard drive manufacturers use decimal (1 GB = 1 billion bytes); OS uses binary (1 GiB = 1,073,741,824 bytes)
✓This is why a "500 GB" drive shows as ~465 GB in your OS
✓Average 4K movie: 15–20 GB | Average photo: 3–5 MB | Average song: 3–5 MB

Data Size

A measure of digital information expressed in bits, bytes, and their multiples (KB, MB, GB, TB).

Data Size Conversion Formula

Each step = ×1,024 (binary) or ×1,000 (decimal/SI)

Where:

Byte= 8 bits (B)
KB= 1,024 bytes (Kilobyte)
MB= 1,024 KB (Megabyte)
GB= 1,024 MB (Gigabyte)
TB= 1,024 GB (Terabyte)

Example:

Size: 5 GB

Result: 5,120 MB = 5,242,880 KB = 5,368,709,120 Bytes

5 × 1,024 = 5,120 MB. 5,120 × 1,024 = 5,242,880 KB.

Want to learn more? Browse our calculation guides and tutorials →

Data Size Converter

Details

📁 Common File Types

Data Size Converter

What Is Data Size?

Key Facts

Formulas & Conversions

Decimal (SI)

Binary (IEC)

Transfer Time

Decimal vs Binary Comparison

History of Data Storage

Research & Standards

IDC Data Age 2025 Report

IEC 80000-13:2021 Standard

NIST SI Guide (SP 330)

Myths & Facts

Frequently Asked Questions

References

Related Calculators

Explore More Calculators

Data Size Converter

Data Size Converter — Answer & Method

Formula: Data Conversion

Example Calculation

Important limitation

Key Facts

Sources & Validation

Related Calculators

Key Takeaways

Data Size Conversion Formula

Where:

Example:

See Also

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Details

📁 Common File Types

Data Size Converter

What Is Data Size?

Key Facts

Formulas & Conversions

Decimal (SI)

Binary (IEC)

Transfer Time

Decimal vs Binary Comparison

History of Data Storage

Research & Standards

IDC Data Age 2025 Report

IEC 80000-13:2021 Standard

NIST SI Guide (SP 330)

Myths & Facts

Frequently Asked Questions

References

Related Calculators

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