OmniCalc

Data Storage Converter

Unit Converters

Convert between bytes, KB, MB, GB, TB, and PB

Buy a "1TB" hard drive, plug it into your computer, and Windows or macOS reports only about 931 GB available. No files were lost — you just ran into one of the most common sources of confusion in computing: two different definitions of the same unit names. Drive manufacturers count in decimal (1 TB = 1,000,000,000,000 bytes), while operating systems display capacity in binary (1 TiB = 1,099,511,627,776 bytes), even though they usually still label it "GB" or "TB" on screen.

Our data storage converter handles both systems so you never have to do the math by hand. Enter a value in bytes, kilobytes, megabytes, gigabytes, terabytes, or petabytes, and instantly convert it using either the binary (1024-based) or decimal (1000-based) standard. Whether you're sizing a cloud storage plan, checking if a video file fits on a USB drive, or just trying to understand why your "512GB" phone never shows 512GB of free space, this tool gives you exact, correct numbers.

Why Data Storage Converter Matters

Storage unit confusion isn't just academic — it affects real purchasing and technical decisions every day. Cloud storage providers, hosting plans, and file transfer limits are usually quoted in decimal units (GB = 10^9 bytes), while your operating system's file explorer, RAM specs, and most software report binary units (GiB = 2^30 bytes) but label them with the same "GB" abbreviation. That mismatch is exactly why a 256GB SSD shows roughly 238 GB usable space in your OS, and why a 64GB SD card in a camera reports fewer available shots than the box math suggests.

Developers, IT professionals, and everyday users all run into this when estimating backup sizes, comparing internet data caps, planning server storage, or figuring out how many photos fit on a memory card. Getting the conversion right prevents under-provisioning storage, avoids nasty surprises when a "500GB" backup plan turns out to hold less than expected, and helps you correctly interpret spec sheets from manufacturers who often use decimal units to advertise larger-sounding numbers.

The Data Storage Converter Formula, Explained

Decimal: 1 KB = 1,000 bytes, 1 MB = 1,000 KB, 1 GB = 1,000 MB. Binary: 1 KiB = 1,024 bytes, 1 MiB = 1,024 KiB, 1 GiB = 1,024 MiB.

There are two competing standards for measuring digital storage. The decimal (SI) system, used by drive and cloud storage manufacturers, treats each unit as a clean multiple of 1,000: 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, 1 GB = 1,000,000,000 bytes, 1 TB = 1,000,000,000,000 bytes, and 1 PB = 1,000 TB.

The binary system, used internally by most operating systems and RAM specifications, is based on powers of 2: 1 KiB (kibibyte) = 1,024 bytes, 1 MiB (mebibyte) = 1,024 KiB = 1,048,576 bytes, 1 GiB (gibibyte) = 1,024 MiB = 1,073,741,824 bytes, and 1 TiB (tebibyte) = 1,024 GiB. The IEC (International Electrotechnical Commission) introduced KiB/MiB/GiB in 1998 specifically to eliminate this ambiguity, but most consumer software still displays "GB" or "TB" on screen when it actually means GiB or TiB.

The practical effect: a decimal terabyte (10^12 bytes) equals about 931.32 GiB when measured in binary units — roughly a 7% shrinkage that has nothing to do with lost storage and everything to do with which counting system is being used.

How to Use the Data Storage Converter: Step by Step

  1. Enter the value you want to convert

    Type the number in your starting unit — for example, 500 if you're converting 500 GB.

  2. Select the source unit

    Choose bytes, KB, MB, GB, TB, or PB for the value you entered.

  3. Choose binary or decimal mode

    Pick decimal (1000-based) to match manufacturer specs, or binary (1024-based) to match what your operating system's file explorer displays.

  4. Select the target unit

    Choose the unit you want to convert to and read the converted result instantly.

Data Storage Converter Examples: Real-World Scenarios

1

Why a "1TB" Drive Shows Less Space

Priya buys a drive labeled 1 TB. The manufacturer defines this as 1,000,000,000,000 bytes (decimal). Her computer's OS reports free space in binary GiB. How much does the OS actually show?

Advertised capacity:1 TB (decimal, 10^12 bytes)
OS display unit:GiB (binary, 2^30 bytes)

Calculation

1,000,000,000,000 bytes ÷ 1,073,741,824 bytes per GiB = 931.32 GiB

Result

The OS reports approximately 931.32 GiB — about 68.7 GB "missing" purely due to the binary vs. decimal counting difference, not a defect or data loss.

2

Converting Photo Library Size for a Cloud Plan

Marcus has 4,000 photos averaging 3.5 MB each on his phone and wants to know if they fit in a 15 GB free cloud storage tier.

Photo count:4,000
Average size:3.5 MB each
Cloud tier:15 GB (decimal)

Calculation

4,000 × 3.5 MB = 14,000 MB = 14,000 ÷ 1,000 = 14 GB

Result

The photo library totals 14 GB, just under the 15 GB free tier — Marcus has about 1 GB of headroom before needing to upgrade or delete files.

3

MB to GB for a Software Download

A game installer is listed as 1,500 MB. A user wants to know the size in both decimal GB and binary GiB to check it fits on a 2 GB USB stick (which the OS reports as ~1.86 GiB usable).

File size:1,500 MB
Decimal conversion:1,500 ÷ 1,000
Binary conversion:1,500 ÷ 1,024

Calculation

Decimal: 1,500 ÷ 1,000 = 1.5 GB | Binary: 1,500 ÷ 1,024 = 1.46 GiB

Result

The 1,500 MB file is 1.5 GB (decimal) or about 1.46 GiB (binary) — either way it comfortably fits on a drive showing 1.86 GiB free.

Common Mistakes to Avoid

  • Assuming GB always means the same number of bytes — decimal GB (10^9 bytes) and binary "GB" as displayed by Windows/macOS (really GiB, 2^30 bytes) differ by about 7%, which compounds to a bigger gap at TB and PB scale.
  • Comparing a manufacturer's advertised drive capacity directly against the OS-reported free space without accounting for the binary/decimal difference, then concluding storage is missing or defective.
  • Mixing up bits and bytes — internet speeds are quoted in megabits per second (Mbps), not megabytes (MB), so an 8 Mbps connection downloads at roughly 1 MB/s, not 8 MB/s.

Tips & Tricks

  • For a quick decimal-to-binary estimate at the GB/GiB scale, subtract about 7% from the decimal value; at TB/TiB scale, subtract about 9%, since the gap widens as units get larger.
  • When shopping for storage, always compare decimal-to-decimal or binary-to-binary — checking a drive's advertised decimal capacity against a cloud plan's decimal quote avoids the conversion trap entirely.

Storage units look simple but hide a real technical distinction that affects how much space you actually get. Use this converter whenever you're comparing drive specs, planning backups, or trying to understand why displayed free space never quite matches the number on the box. For related conversions, check out our file size converter and other unit tools to keep every measurement in your workflow consistent.

Data Storage Converter — Frequently Asked Questions

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Authoritative References

IEC 80000-13 — Binary Prefixes for Digital Information

iec.ch — Official standard defining KiB, MiB, GiB binary prefixes

NIST — Prefixes for Binary Multiples

nist.gov — Government reference explaining binary vs. decimal storage prefixes

External links open in a new tab. OmniCalc.us is not affiliated with these organisations.

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