How many kilobytes are in a gigabyte?

Under the SI decimal standard, 1 GB = 1,000,000 KB (1,000 MB per GB × 1,000 KB per MB). Under the binary IEC standard, 1 GiB = 1,048,576 KiB (1,024 MiB per GiB × 1,024 KiB per MiB). The ~4.86% difference explains why a 512 GB SSD appears as roughly 477 GiB in an OS.

Why does this tool show two different answers?

The SI system defines kilo and giga as powers of 1,000 (used by storage manufacturers and networking), while the IEC binary system uses powers of 1,024 (used by operating systems and memory). Both definitions are in widespread use, so the tool shows both.

When should I use GB versus GiB?

Use GB (SI, 1,000,000 KB) when working with hard drive specs, SSDs, networking, or any context where manufacturers state capacities. Use GiB (binary, 1,048,576 KiB) when checking OS-reported disk space, RAM, or writing code that works with powers of 2.

How do I convert kilobytes back to gigabytes?

Divide KB by 1,000,000 for SI gigabytes, or divide KiB by 1,048,576 for binary gibibytes.

Is the converter accurate for very large values?

Yes. The tool uses JavaScript 64-bit floating-point arithmetic and formats results to up to 8 significant decimal places, which is accurate for all practical gigabyte values.

Gigabytes to Kilobytes Converter

Enter gigabytes and get the equivalent in kilobytes (SI decimal) and kibibytes (binary IEC) with a step-by-step breakdown.

Gigabytes Input

Amount (GB / GiB)

Quick values

SI decimal: 1 GB = 1,000,000 KB
Binary IEC: 1 GiB = 1,048,576 KiB

SI Decimal — KB

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Enter a value to see the calculation.

Binary IEC — KiB

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Enter a value to see the calculation.

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Summary

This tool converts gigabytes (GB) to kilobytes (KB) using both the SI decimal standard (1 GB = 1,000,000 KB) and the binary IEC standard (1 GiB = 1,048,576 KiB). Hard drive manufacturers use SI units while operating systems report storage in binary units, which is why a "500 GB" drive shows as roughly 465 GiB in Windows or macOS. Seeing both values eliminates confusion when comparing advertised capacities to what your OS reports.

How it works

Enter the number of gigabytes in the input field.
For the SI result: multiply GB by 1,000,000 (1 GB = 1,000 MB × 1,000 KB = 1,000,000 KB).
For the binary result: multiply GiB by 1,048,576 (1 GiB = 1,024 MiB × 1,024 KiB = 1,048,576 KiB).
Both results appear instantly below the input field.
Use the copy button next to each result to grab the value.

Use cases

Understand how much disk space in KB a gigabyte-sized file occupies.
Convert storage quotas stated in GB to KB for system configuration.
Verify file transfer totals reported in gigabytes against kilobyte limits.
Cross-check SI versus binary kilobyte definitions in technical specs.
Translate database record size estimates from GB to KB for indexing budgets.
Convert IoT or embedded-system capacity figures between GB and KB.

Frequently Asked Questions

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