How many bytes are in a gigabyte?

Using the SI decimal standard: 1 GB = 1,000,000,000 bytes (10^9). Using the IEC binary standard: 1 GiB (gibibyte) = 1,073,741,824 bytes (2^30). Storage manufacturers use GB; most operating systems use GiB but label it "GB."

Why does my 1 TB hard drive show less space in Windows?

The manufacturer rates the drive in SI gigabytes (powers of 1,000). Windows reports capacity in gibibytes (powers of 1,024) while calling them "GB." Since 1 GiB > 1 GB, the same byte count results in a smaller number when expressed in GiB.

What is the difference between GB and GiB?

GB (gigabyte) follows the SI decimal system: 1 GB = 1,000 MB = 1,000,000 KB = 1,000,000,000 bytes. GiB (gibibyte) follows the IEC binary system: 1 GiB = 1,024 MiB = 1,048,576 KiB = 1,073,741,824 bytes. 1 GiB is about 7.37% larger than 1 GB.

How do I convert megabytes to gigabytes?

Multiply megabytes by 1,000,000 to get bytes first, then divide by 1,000,000,000 for GB. Shortcut: divide megabytes by 1,000 for GB (SI), or divide mebibytes by 1,024 for GiB (binary).

How accurate is this converter for very large byte counts?

The converter uses JavaScript 64-bit floating-point (IEEE 754 double precision), which handles integers exactly up to 2^53 — about 9 quadrillion bytes (9 petabytes). For any practical storage size, the result is exact.

Bytes to Gigabytes Converter

Enter a byte value and instantly get gigabytes (GB, decimal SI) and gibibytes (GiB, binary IEC), plus a quick-reference table.

Input — Bytes

Number of bytes

SI vs. binary: 1 GB (gigabyte, decimal) = 1,000,000,000 bytes. 1 GiB (gibibyte, binary) = 1,073,741,824 bytes. Storage specs use GB; your OS reports GiB (but often labels them "GB").

Results

Enter a byte value and click Convert.

Reference Table — Common Byte Counts

Quick lookup for typical file and storage sizes.

Bytes	GB (SI, ÷10⁹)	GiB (binary, ÷2³⁰)	Typical example

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Summary

This tool converts a byte count into gigabytes using both the SI decimal standard (1 GB = 1,000,000,000 bytes) and the IEC binary standard (1 GiB = 1,073,741,824 bytes). Storage manufacturers and current macOS use decimal gigabytes, while Windows commonly reports binary gibibyte quantities labeled as "GB." That difference explains why a "500 GB" hard drive shows roughly 465 GB in Windows. Use the reference table below the converter to look up common byte values at a glance.

How it works

Enter the number of bytes in the input field.
The tool divides by 1,000,000,000 to get decimal gigabytes (GB).
It also divides by 1,073,741,824 to get binary gibibytes (GiB).
Results appear instantly with up to 10 significant digits.
Use the copy buttons to grab any result value.
Scroll down for a reference table of common byte counts in GB and GiB.

Use cases

Check how many GB a file size in bytes occupies on a storage device.
Understand why a "500 GB" drive shows less space in your operating system.
Convert database or log file sizes from bytes to gigabytes for reporting.
Translate API response sizes into human-readable gigabyte values.
Verify storage estimates when working with cloud storage pricing by the GB.
Cross-reference OS-reported sizes (GiB) against hardware specs (GB).

Frequently Asked Questions

Last updated: 2026-06-19 · Reviewed by Nham Vu