FileSizeCalc

TB to GB Converter — Terabytes to Gigabytes

A TB to GB converter turns terabytes into gigabytes — the pair you need when a NAS, drive or cloud plan is sold in TB but your tools and quotas count in GB.

Quick answer: 1 TB = 1,024 GB in binary (GiB) or 1,000 GB decimal — the label on the box. Windows will report a 1 TB drive as 931 GiB because it divides the decimal byte count by 1,024³.

Which convention should the plain KB/MB/GB/TB labels use?
Result
1,024
1 TB = 1,024 GB
Exact factors
1 TB =1,024 GB
1 GB =0.000976563 GB
Bytes per unit1,099,511,627,776 B = TB
Same value, other convention
With the 1000 rule1,000 GB

The two lines are the same file — only the definition of “GB” differs. This 2.4% gap per step is why a 1 TB drive shows 931 GiB in Windows.

Common TB → GB values
TBGB
0.5512
11,024
22,048
55,120
1010,240
5051,200
100102,400
500512,000
1,0001,024,000
If you are converting for a download estimate, remember that network speeds are quoted in bits per second (Mbps) while file sizes are bytes — 100 Mbps moves about 12.5 MB per second. Use the download time calculator for that math.
Results are computed locally in your browser. Binary (1024) is what Windows and most disk tools show; decimal (1000) is what drive and cloud vendors print on the box — the same file can honestly be described by both numbers.
Core facts
1 TB decimal1,000 GB = 1,000,000,000,000 bytes
1 TiB binary1,024 GiB = 1,099,511,627,776 bytes
1 TB drive in Windows931.32 GiB
2 TB drive in Windows1,862.65 GiB · 4 TB → 3,725.29 GiB
Other labels1 TB = 1,000 GB · 1 TiB = 1,024 GiB

The 931 GiB question answered

A 1 TB drive contains 1,000,000,000,000 bytes — the vendor is right. Windows divides those bytes by 1,073,741,824 (1 GiB) and gets 931.32, then labels the result “GB”. Both statements are true; only the naming is inconsistent. Converting 1 TB to 1,024 GB and expecting Windows to agree is the single most common units mistake on this site.

Sizing backups and NAS arrays

When planning storage, work in the same unit all the way through. A 4 TB drive holds 4,000 GB decimal, which is 3,725 GiB in Windows or 3,638 GiB usable after a typical 2–3% file-system and snapshot overhead. RAID 1 halves it; RAID 5 loses one drive plus a few percent. Converting at each step, rather than assuming equal, prevents the classic “why is my new 4 TB array only 3.6 TB” surprise.

When to use this calculator

  • Reconciling a drive's advertised TB with the capacity Windows or macOS reports.
  • Converting cloud plan sizes (e.g. 2 TB) into the GB your backup tool counts.
  • Planning how many GB of footage a TB of security storage actually holds.
  • Explaining the missing space in a new NAS to a colleague without blaming the vendor.

Frequently asked questions

Frequently Asked Questions

How many GB in a TB?
1,000 GB decimal (the label on the box) or 1,024 GB binary. In practice a 1 TB drive shows 931 GiB in Windows.
How many GB is 2 TB?
2,000 GB decimal, which displays as 1,862.65 GiB in binary.
Why does my 1 TB SSD say 931 GB?
Because 10¹² bytes ÷ 2³⁰ bytes per GiB = 931.32. Nothing is missing; the label and the display use different definitions.
Is a TB 1000 or 1024 GB?
The decimal terabyte is 1,000 GB = 10¹² bytes. The binary tebibyte is 1,024 GiB. Drives are sold in decimal; most software displays binary.
How much is 1 TB in MB?
1,000,000 MB decimal, or 1,048,576 MiB binary — roughly a million megabytes either way.

More guides

Why a 1 TB Drive Shows 931 GB
The decimal-versus-binary answer in plain language
How Many GB in a TB
1,000 or 1,024 — and what that means for real drives