GB to TB Converter
Convert gigabytes to terabytes for hard drives, NAS planning and backup sizing. 1 TB = 1000 GB (decimal) or 1024 GiB (binary), both shown.
Last updated: May 2026
Enter a value to see the conversion instantly.
How to convert gigabytes to terabytes
Large libraries, backups and drive purchases are easier to judge in terabytes, while many file managers and app dashboards still report gigabytes. For planning purposes, 1 GB equals 0.001 TB exactly, the same value written at a different scale.
The formula is terabytes = gigabytes ÷ 1000. In practice, this is useful when deciding whether a new SSD, NAS volume or backup target is large enough for the total amount of data you expect to store.
Typical use cases
- Comparing media libraries with drive capacity
- Planning backups for photos, games, video or project archives
- Checking how much room is left before a storage upgrade is needed
A common use case is a home NAS or media server. People often think in terabytes for buying storage, but the software may display gigabytes.
Quick reference
| GB | TB |
|---|---|
| 100 | 0.1 |
| 1 | 0.001 |
| 500 | 0.5 |
| 1000 | 1 |
| 2000 | 2 |
Related tools
Decimal TB (drive makers) vs binary TiB (what Windows shows)
Drive manufacturers define 1 TB as exactly 1,000,000,000,000 bytes (decimal). Windows counts the same bytes using binary gibibytes (1 GiB = 1,073,741,824 bytes), then labels the result GB. The gap is about 7.4%: a "1 TB" drive shows as 931 GB in Windows. macOS switched to decimal labelling in OS X 10.6 Snow Leopard, so the same drive shows as 1 TB there. Linux distributions have largely adopted correct GiB labels.
This means the same drive can appear to hold different amounts depending on which OS or tool you use, even though the byte count is identical. When planning storage, decide which convention you are working in and stay consistent throughout.
Real-world content sizing
| Content type | Typical size | Per 1 TB (decimal) |
|---|---|---|
| JPEG photo (12 MP, compressed) | 3-5 MB | 200,000-333,000 photos |
| RAW photo (24 MP) | 25-45 MB | 22,000-40,000 photos |
| 1080p video (H.264, 10 Mbps) | ~4.5 GB/hour | ~220 hours |
| 4K video (H.265, 25 Mbps) | ~11 GB/hour | ~90 hours |
| 4K RAW / ProRes (100 Mbps) | ~45 GB/hour | ~22 hours |
| Modern AAA game | 50-150 GB | 7-20 games |
These are estimates; actual sizes depend on codec settings, scene complexity and camera model. Always reserve at least 10-15% of a drive's capacity free: drives slow noticeably and fragment faster when nearly full.
Frequently Asked Questions
Why do backup systems suddenly demand TB numbers?
Professional storage and backup targets are sold in terabytes (NAS, external drives, cloud storage tiers). But when you check total media on your system, it's reported in gigabytes. A photo library of 800 GB needs to fit in "1 TB" NAS, this calculator confirms it has just enough room (with 200 GB free). Without conversion, you risk buying undersized storage and running out mid-backup.
Do TB and Terabytes always mean the same thing?
Not exactly. TB in marketing (like "1TB drive") usually means 1 trillion bytes (decimal). Some systems use TiB (tebibytes, binary = 1.0995 trillion bytes). A 1 TB advertised drive has slightly less usable space after formatting, typically 931-950 GB depending on the file system. This page uses decimal conversion, matching how drives are marketed and sold.
Why is my backup software saying my 2TB drive only holds 1.8TB?
Because formatting (creating a file system) consumes ~8% of raw storage. Overhead for partition tables, file allocation tables, and reserved sectors reduces effective capacity. Additionally, if the drive uses binary convention internally while advertising decimal TB, the mismatch compounds. Always budget 10-15% overhead when planning backups, a 2TB drive in practice holds ~1.7-1.8 TB of actual files.
What is the difference between a TB (terabyte) and a TiB (tebibyte)?
1 TB = 1,000,000,000,000 bytes (decimal), used by drive manufacturers, cloud storage providers and most marketing. 1 TiB = 1,099,511,627,776 bytes (binary), roughly 9.95% larger. Windows shows drive sizes in TiB but labels them TB; macOS uses decimal TB; Linux has largely moved to labelling in GiB/TiB correctly. The same 1 TB drive therefore appears as 931 GB on Windows, 1.0 TB on macOS and 931 GiB on a modern Linux system. The byte count is identical; only the unit definition differs.
How much 4K video footage fits on a 1 TB drive?
At typical H.265 streaming compression (25 Mbps), 4K video takes about 11 GB per hour, so a 1 TB drive holds roughly 90 hours. Camera-captured 4K at higher bitrates (50-100 Mbps for ProRes or cinema RAW) takes 22-45 GB per hour, leaving room for around 22-45 hours. Subtract 10% overhead for the file system and keep at least 15% free to maintain drive performance. For professional video work, plan storage in terms of GB per hour for your specific camera and codec rather than relying on round numbers.