Terabytes to Gigabytes Converter

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Enter a storage capacity in TB to see its decimal GB value and how the same bytes can display in GiB.

Gigabytes from decimal terabytes
Decimal storage uses 1 TB = 1,000 GB.
If the entered number means TiB
Use this only if the source explicitly says TiB. It uses 1 TiB = 1,024 GiB and is not the decimal TB-to-GB answer.
Same decimal TB capacity in GiB
Software using binary units may show this smaller number for the same bytes.
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How to use our Terabytes to Gigabytes Converter

  1. Find the capacity on a drive label, storage plan, invoice, backup plan, or storage display.
  2. Enter the number in "Storage capacity (TB)". You can enter a bare number such as "2.5" or add "TB", such as "2.5 TB".
  3. Click "Calculate" to get the main decimal GB answer.
  4. Read the GiB cards only when comparing with software that uses binary units or a source that explicitly says TiB.
  5. Sanity-check the main answer: it should equal the TB amount multiplied by 1,000.
Example inputs for Terabytes to Gigabytes Converter
Example inputs for Terabytes to Gigabytes Converter

Definitions

TB (terabyte): A decimal storage unit equal to 1,000,000,000,000 bytes. One TB equals 1,000 GB.

GB (gigabyte): A decimal storage unit equal to 1,000,000,000 bytes.

TiB (tebibyte): A binary storage unit equal to 240 bytes. One TiB equals 1,024 GiB.

GiB (gibibyte): A binary storage unit equal to 230 bytes, or 1,073,741,824 bytes.

Same bytes: The stored byte count does not change when it is expressed in different units; only the displayed number changes.

Common mistakes and quick fixes

Mistake: Multiplying TB by 1,024 and labeling the answer GB.
Fix: For decimal storage units, use 1 TB = 1,000 GB. The 1,024 relationship is for TiB and GiB.

Mistake: Treating TB and TiB as identical units.
Fix: Use TB for a decimal label. Use TiB only when the source explicitly uses TiB or binary units.

Mistake: Assuming a lower GiB number means storage is missing.
Fix: Compare the byte amount. The same decimal TB capacity has a smaller numeric value when shown in GiB.

Mistake: Entering commas incorrectly, such as "1,01".
Fix: Use commas only as thousands separators, such as "1,000.5", or enter "1000.5".

Mistake: Entering a range or two capacities, such as "1 to 2 TB".
Fix: Enter one nonnegative capacity for each conversion.

Limitations & Key Assumptions / Boundary Conditions

  • The entered value is treated as decimal TB, so the main answer uses 1 TB = 1,000 GB.
  • The "If the entered number means TiB" value is an alternate interpretation of the number, not the TB-to-GB conversion.
  • A device or app may round its displayed capacity or use GB, GiB, or another label convention.
  • Free space can be lower than total capacity because files, formatting, and system data use storage.
  • The calculator accepts one finite, nonnegative capacity. It does not accept ranges, formulas, or units other than TB.

Methodology

Calculation method

The main answer uses decimal storage units. One TB contains 1,000 GB.

GB = TB * 1000

The first supporting card changes the meaning of the entered number from TB to TiB. Binary prefixes use powers of two, and one TiB contains 1,024 GiB.

GiB if entered value is TiB = entered number * 1024

The second supporting card keeps the decimal TB byte count unchanged, then expresses that byte count in GiB.

GiB for same bytes = TB * 1000000000000 / 1073741824

Worked example

For 2.5 TB, the main calculation is 2.5 * 1,000 = 2,500 GB. Those same 2.5 decimal TB equal about 2,328.306 GiB. If a source actually says 2.5 TiB, that amount equals 2,560 GiB.