How many gigabytes are in a terabyte?

Using the SI decimal standard: 1 TB = 1,000 GB. Using the IEC binary standard: 1 TiB (tebibyte) = 1,024 GiB (gibibytes). Storage manufacturers use TB; most operating systems use TiB but label them "TB."

Why does my 1 TB hard drive show less than 1,000 GB in my OS?

The manufacturer rates capacity in SI terabytes (powers of 1,000). Your OS typically reports in tebibytes (powers of 1,024) while calling them "TB." Since 1 TiB = 1,099,511,627,776 bytes vs 1 TB = 1,000,000,000,000 bytes, the same byte count results in a smaller number when expressed in TiB.

What is the difference between GB and GiB?

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

How do I convert terabytes to gigabytes?

Multiply the terabyte value by 1,000 to get SI gigabytes (GB). Multiply tebibytes by 1,024 to get binary gibibytes (GiB). For most practical purposes, multiplying by 1,000 matches what storage hardware advertises.

How accurate is this converter for very large values?

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

Terabytes to Gigabytes Converter

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

Input — Terabytes

Number of terabytes

SI vs. binary: 1 TB (terabyte, decimal) = 1,000 GB. 1 TiB (tebibyte, binary) = 1,024 GiB. Storage specs use TB; your OS reports TiB (but often labels them "TB").

Results

Enter a terabyte value and click Convert.

Reference Table — Common Terabyte Counts

Quick lookup for typical drive and storage sizes.

Terabytes (TB)	GB (SI, ×1,000)	GiB (binary, ×1,024)	Typical example

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Summary

This tool converts a terabyte count into gigabytes using both the SI decimal standard (1 TB = 1,000 GB) and the IEC binary standard (1 TiB = 1,024 GiB). Storage manufacturers advertise capacity in SI units, while most operating systems report sizes in binary units — often labeling TiB as "TB." That mismatch explains why a "1 TB" drive can show a slightly different size in your OS. Use the reference table to look up common terabyte values at a glance.

How it works

Enter the number of terabytes in the input field.
The tool multiplies by 1,000 to get decimal gigabytes (GB, SI).
It also multiplies by 1,024 to get binary gibibytes (GiB, IEC), treating the input as tebibytes.
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 terabyte counts in GB and GiB.

Use cases

Check how many gigabytes a hard drive rated in terabytes actually provides.
Understand the difference between advertised storage (TB) and OS-reported sizes (TiB).
Convert SSD or NAS capacity from terabytes to gigabytes for detailed planning.
Translate backup sizes into gigabytes for quota tracking.
Verify storage estimates when working with cloud pricing billed per GB.
Cross-reference OS-reported sizes (GiB) against hardware specs (GB).

Frequently Asked Questions

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