Is 1 KB equal to 1,000 or 1,024 bytes?

It depends on the context. In strict SI (decimal) usage, 1 KB equals exactly 1,000 bytes. In binary (IEC) usage, the equivalent unit is 1 KiB, which equals 1,024 bytes. Hard drive manufacturers use decimal; operating systems and RAM specifications traditionally use binary.

What is a KiB and how is it different from a KB?

KiB stands for kibibyte and equals 1,024 bytes exactly. KB (kilobyte) in strict SI means 1,000 bytes. The IEC introduced the Kibi/Mebi/Gibi prefixes in 1998 to eliminate the long-standing ambiguity. In everyday speech most people still say KB when they mean KiB.

Why does my 1 TB hard drive show only about 931 GB in Windows?

Drive manufacturers label capacity using decimal gigabytes (1 GB = 1,000,000,000 bytes). Windows measures and displays space using binary gibibytes (1 GiB = 1,073,741,824 bytes) but labels them GB. Dividing 1,000,000,000,000 by 1,073,741,824 gives roughly 931, so the drive appears smaller even though it is not.

When should I use Binary (1024) vs Decimal (1000)?

Use Binary (1024) when working with RAM, OS-reported file sizes, Linux utilities, or software that follows IEC conventions. Use Decimal (1000) when reading hard drive or SSD marketing specs, network bandwidth figures (Mbps, Gbps), or SI-compliant scientific contexts.

How do I convert MB to GB?

In binary mode, divide the number of MiB by 1,024 to get GiB (e.g. 2,048 MiB = 2 GiB). In decimal mode, divide the number of MB by 1,000 to get GB (e.g. 2,000 MB = 2 GB). Enter the value here with MB selected and the GB result appears instantly.

Can I copy a single result to paste into code?

Yes. Each result card has a Copy button that puts the numeric value on your clipboard. You can also press Cmd+Enter (or Ctrl+Enter on Windows) to copy all results at once as a JSON object, ready to paste into a script or config file.

Is my input data sent anywhere?

No. All calculations are performed locally using standard arithmetic. No value you enter is transmitted to any server.

What units does the converter support?

The converter supports Bytes (B), Kilobytes/Kibibytes (KB/KiB), Megabytes/Mebibytes (MB/MiB), Gigabytes/Gibibytes (GB/GiB), Terabytes/Tebibytes (TB/TiB), and Petabytes/Pebibytes (PB/PiB), in both decimal and binary modes.

Bytes & Data Size Converter

What Is a Byte?

A byte is the fundamental unit of digital storage, made up of 8 bits. Everything stored on a computer, from a single text character to a full-length film, is measured in bytes or multiples of bytes. When you download a file, check your phone's storage, or provision a cloud server, you are working with byte-based units every day.

Two Systems, One Confusion

The confusing part of data sizes is that the industry uses two different multiplier systems, and both historically used the same names for different values.

Binary (IEC, base 1024): Each unit is 1,024 times the previous one. This matches how computers address memory, since 1,024 is a power of 2. The IEC standard introduced the prefixes Kibi-, Mebi-, Gibi-, and so on, to be unambiguous, producing KiB, MiB, GiB.

Decimal (SI, base 1000): Each unit is exactly 1,000 times the previous one. Hard drive manufacturers, network engineers, and the SI standards body use this system. A "1 TB" hard drive contains 1,000,000,000,000 bytes by this count.

The practical difference compounds quickly. One gibibyte (GiB) equals 1,073,741,824 bytes, while one gigabyte (GB) equals exactly 1,000,000,000 bytes. That is a 7.4% gap, which means a "500 GB" drive holds only about 465 GiB as measured by most operating systems.

Why Does Windows Show a Smaller Size Than the Box Claims?

A 1 TB hard drive ships with exactly 1,000,000,000,000 bytes, as advertised by the manufacturer using the decimal system. Windows, however, reports file sizes using binary division while still labeling the result "GB." So Windows displays the result as 0.91 "GB" instead of 1 "GB." The drive is not smaller than promised. The OS and the manufacturer are speaking different languages.

macOS switched to decimal reporting in macOS 10.6 to match the label on the box. Linux tools report in either system depending on the utility. This is why the same file can appear as a different size depending on what tool you use to inspect it.

The KiB vs KB Problem

Historically, the prefix "kilo" meant both 1,000 in SI and 1,024 in computing. In 1998 the IEC formalized new binary prefixes to eliminate the ambiguity.

KiB (kibibyte) = 1,024 B, the binary unit
KB (kilobyte) = 1,000 B, the strict SI decimal unit

In practice, most consumer software and operating systems still write "KB" when they mean "KiB." The formal prefixes KiB, MiB, GiB are mainly used in technical standards, Linux kernel documentation, and academic papers. When you see "512 KB RAM" in a specification, the author almost certainly means 524,288 bytes, not 512,000.

How the Converter Works

Enter any value, select its source unit, and the tool calculates the equivalent in all other units simultaneously using the formula:

bytes = input_value x base^(from_unit_index)
target_value = bytes / base^(target_unit_index)

Toggle between Binary (1024) and Decimal (1000) to see the same number expressed in both systems. Each result card has a one-click Copy button for pasting individual values into scripts, specs, or documentation. Press Cmd/Ctrl+Enter to copy all results as a JSON object.

Practical Use Cases

Developers: Convert API response sizes, set upload limits, size Docker volumes, configure database buffer pools, or verify that a payload is within expected bounds.

System administrators: Calculate disk partition sizes, network throughput requirements, RAM allocations, and log retention budgets.

Network engineers: Bandwidth is quoted in decimal bits per second (Mbps, Gbps). File sizes are often quoted in binary bytes (MiB). Converting between the two is essential for accurate transfer-time estimates.

Data analysts: When loading files into pandas, Spark, or BigQuery, knowing the exact byte count helps you choose buffer sizes and chunk sizes that align to memory page boundaries for better performance.

Content creators: Understanding the difference between a "1 GB" cloud storage quota and the actual space your 4K video files consume prevents unpleasant surprises at upload time.

Common Mistakes to Avoid

Mixing systems in calculations: If you multiply a "2 GB network quota" (decimal, 2,000,000,000 bytes) by your file size measured in MiB (binary, 1,048,576 bytes each), you will get the wrong count of files that fit.

Assuming labels are canonical: A label like "512 MB" may mean different things on a USB drive spec sheet versus in a Node.js flag. Check the context before assuming which base applies.

Forgetting filesystem overhead: Even if a partition is exactly 100 GiB, usable space is always less due to filesystem metadata, inode tables, and reserved blocks. This converter gives you raw byte math; overhead is tool-dependent.

Ignoring precision at the edges: Very small values (under 1 KB) or very large ones (over 1 PB) can lose apparent precision when formatted. The converter automatically switches to scientific notation when the formatted number would lose significant digits.