How many GB are in 1 TB (SI/decimal)?

In the SI (International System of Units) standard, 1 terabyte (TB) equals exactly 1,000 gigabytes (GB). This is the standard used by hard drive and SSD manufacturers, internet providers, and macOS (since 10.6).

How many GiB are in 1 TiB (binary/IEC)?

In the IEC binary standard, 1 tebibyte (TiB) equals exactly 1,024 gibibytes (GiB). Windows File Explorer uses this binary calculation but still displays the label "TB", which is why a "1 TB" drive appears as roughly 931 GB in Windows.

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

Drive manufacturers define 1 TB as 1,000,000,000,000 bytes (SI decimal). Windows measures capacity in binary tebibytes (1 TiB = 1,099,511,627,776 bytes) but labels the result "TB". Dividing the byte count by the binary factor gives approximately 0.909 TiB, displayed as roughly 931 GB.

Which standard does macOS use for TB?

Since macOS 10.6 (Snow Leopard), Apple uses SI decimal units. So 1 TB in Finder equals exactly 1,000,000,000,000 bytes, matching the advertised capacity on the drive's packaging.

What is the difference between TB and TiB?

TB (terabyte) is the SI decimal unit: 1 TB = 1,000 GB = 10^12 bytes. TiB (tebibyte) is the IEC binary unit: 1 TiB = 1,024 GiB = 2^40 bytes. They differ by about 9.95%. Confusingly, many tools and operating systems use "TB" when they actually mean "TiB".

How do I convert GB to TB mentally?

For a quick SI estimate, divide the GB value by 1,000 (move the decimal point three places left). For example, 2,500 GB ÷ 1,000 = 2.5 TB. For binary, divide by 1,024 — 2,500 GiB ÷ 1,024 ≈ 2.44 TiB.

Gigabytes to Terabytes Converter

Name: Gigabytes to Terabytes Converter
Availability: InStock
Author: Nham Vu

Enter a value in gigabytes to get the terabyte equivalent in both SI (1000) and binary (1024) standards instantly.

Storage Unit Converter

Gigabytes (GB)

Terabytes (TB) — SI decimal

Enter a value on the left to see results

Common Storage Size Reference

Click a row to load it

Device / Storage	GB	TB (SI)	TiB (bin)

Summary

Enter a value in gigabytes to get the terabyte equivalent in both SI (1000) and binary (1024) standards instantly.

How it works

Type a value in the Gigabytes field to see the result in Terabytes.
Switch to TB input mode to convert Terabytes back to Gigabytes.
Results appear for both SI (1 TB = 1,000 GB) and binary IEC (1 TiB = 1,024 GiB) standards simultaneously.
Click any row in the reference table to load that size into the converter.
Click "Clear" to reset all fields.

Use cases

Determine how many terabytes a large backup collection occupies on a NAS or cloud drive.
Compare drive capacity reported by operating systems (binary GiB) vs. manufacturer specs (decimal GB).
Estimate how many gigabytes remain when a storage quota is given in terabytes.
Verify that a database export measured in GB fits within a TB-scale volume.
Convert video archive sizes from GB to TB for planning long-term storage costs.
Understand the GB-to-TB gap when provisioning cloud block storage volumes.
Check whether a server disk measured in terabytes has enough space for a GB-sized dataset.
Budget data transfer costs when a cloud provider charges per terabyte but files are listed in gigabytes.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu