💾 Free Storage Tool

TB to GB
Calculator

Convert terabytes to gigabytes instantly — with binary (TiB/GiB) conversions, full storage unit breakdown, and device capacity comparisons.

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GB = TB × 1,000

Terabytes (TB)

Gigabytes (GB)

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TB to GB Calculator: Convert Storage Instantly

A TB to GB calculator is an essential tool for anyone working with digital storage — whether you’re buying a new hard drive, comparing cloud storage plans, planning enterprise infrastructure, or simply trying to understand why your “1 TB” drive shows less space in your operating system. This calculator instantly converts between terabytes and gigabytes using both the decimal (SI) and binary (IEC) standards, eliminating the confusion that affects millions of storage purchases every year.

💾 Quick answer: 1 TB = 1,000 GB (decimal/SI standard, used by manufacturers). 1 TiB = 1,024 GiB (binary/IEC standard, sometimes shown by operating systems). The difference explains why your new drive shows less capacity than advertised.

What Is a Terabyte?

A terabyte (TB) is a unit of digital information storage equal to 1,000 gigabytes under the decimal (SI) standard used by storage manufacturers, or 1,024 gibibytes (technically a tebibyte, TiB) under the binary standard used internally by computer operating systems. One terabyte can store approximately 250,000 photos, 200,000 songs, or 500 hours of HD video — making it the standard unit for modern consumer and enterprise storage devices.

What Is a Gigabyte?

A gigabyte (GB) is a unit of digital storage equal to 1,000 megabytes (decimal) or 1,024 mebibytes (binary). It’s the most commonly referenced unit in everyday computing — used to describe app sizes, photo libraries, video files, RAM capacity, and mobile data plans. One gigabyte holds roughly 250 photos, 200 songs, or 2 hours of standard-definition video.

TB to GB Formula

Decimal (SI) formula: GB = TB × 1,000
Example: 2 TB × 1,000 = 2,000 GB

Binary (IEC) formula: GiB = TiB × 1,024
Example: 2 TiB × 1,024 = 2,048 GiB

Decimal vs Binary Units

This is the single most confusing aspect of digital storage. There are two competing standards for measuring storage capacity, and they produce different results for the same physical amount of data:

Standard	Base	1 KB =	1 MB =	1 GB =	1 TB =	Used by
Decimal (SI)	1000	1,000 B	1,000 KB	1,000 MB	1,000 GB	Manufacturers, marketing
Binary (IEC)	1024	1,024 B	1,024 KiB	1,024 MiB	1,024 GiB	Operating systems (file size display)

SI vs IEC Standards

The International System of Units (SI) defines prefixes like kilo, mega, giga, and tera as powers of 1,000 — consistent with all other scientific measurement (kilometres, kilograms, etc.). Storage manufacturers use this standard because it’s simpler and produces larger “round” numbers for marketing.

The International Electrotechnical Commission (IEC) introduced binary prefixes — kibi, mebi, gibi, tebi (KiB, MiB, GiB, TiB) — specifically to distinguish binary (powers of 1,024) from decimal (powers of 1,000) measurements. Despite this official distinction existing since 1998, most operating systems still label binary values with decimal unit names (showing “GB” when they mean “GiB”) — which is the root cause of the “missing storage” confusion.

Storage Manufacturers Explained

When you buy a “1 TB” hard drive, the manufacturer means exactly 1,000,000,000,000 bytes (decimal). However, Windows and most operating systems calculate and display storage using binary math, showing this same drive as approximately 931 GB. The drive isn’t missing storage — it’s a unit conversion artifact: 1,000,000,000,000 bytes ÷ 1,073,741,824 (bytes per GiB) ≈ 931.

SSD vs HDD Capacities

Advertised Capacity	Actual Bytes	Windows Shows (GiB)	“Missing” Space
256 GB SSD	256,000,000,000	~238 GB	~18 GB
512 GB SSD	512,000,000,000	~477 GB	~35 GB
1 TB SSD	1,000,000,000,000	~931 GB	~69 GB
2 TB SSD	2,000,000,000,000	~1,863 GB	~137 GB
4 TB HDD	4,000,000,000,000	~3,726 GB	~274 GB

Cloud Storage Uses

Most major cloud providers (Google Drive, Dropbox, OneDrive, iCloud) use decimal (SI) units for their storage plans, matching manufacturer conventions. AWS S3 and Azure Blob Storage similarly bill using decimal GB/TB for pricing tiers, though their consoles sometimes display binary-equivalent figures for technical accuracy. Always check the provider’s documentation to confirm which standard applies to your specific plan or billing.

Enterprise Storage Planning

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NAS Sizing

When planning NAS or SAN capacity, always calculate using decimal (manufacturer) units, then subtract 7-10% for binary OS overhead and filesystem formatting losses.

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Backup Capacity

Backup solutions typically require 1.5-3× the source data size to accommodate versioning, snapshots, and redundancy (RAID overhead).

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Cloud Migration

When migrating to cloud storage, confirm whether your provider bills in decimal or binary units — this can create 5-7% billing discrepancies at scale.

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Cost Planning

Enterprise storage costs are typically quoted per decimal TB ($/TB/month). Always verify usable vs raw capacity after RAID and redundancy overhead.

Common Storage Mistakes

Assuming “missing” storage is a defect: The gap between advertised and displayed capacity is a unit conversion artifact, not lost or defective storage.
Confusing bits and bytes: Network speeds are measured in bits per second (Mbps), while file sizes are in bytes (MB). 8 bits = 1 byte, so a “100 Mbps” connection downloads at approximately 12.5 MB/s maximum.
Ignoring filesystem overhead: Formatting (NTFS, APFS, ext4) consumes additional space beyond the binary/decimal conversion — typically 1-3% more.
Not accounting for RAID overhead: RAID 1 halves usable capacity; RAID 5/6 reserve capacity for parity data — always calculate usable, not raw, capacity.

Real-Life Examples

Scenario	TB Value	GB (Decimal)	GiB (Binary)
Smartphone storage	0.25 TB (256GB)	250 GB	238.4 GiB
Laptop SSD	1 TB	1,000 GB	931.3 GiB
External backup drive	4 TB	4,000 GB	3,725.3 GiB
NAS array (4-bay)	16 TB	16,000 GB	14,901.2 GiB
Enterprise SAN	100 TB	100,000 GB	93,132.3 GiB

Storage Conversion Tables

From	To Bytes	To KB	To MB	To GB
1 KB	1,000	1	0.001	0.000001
1 MB	1,000,000	1,000	1	0.001
1 GB	1,000,000,000	1,000,000	1,000	1
1 TB	1,000,000,000,000	1,000,000,000	1,000,000	1,000
1 PB	10^15	10^12	10^9	1,000,000

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Frequently Asked Questions

How many GB are in 1 TB?

1 TB equals 1,000 GB using the decimal (SI) standard, which is what storage manufacturers use on packaging and specifications. Using the binary (IEC) standard, 1 TiB equals 1,024 GiB. Most consumer contexts (buying a drive, cloud storage plans) use the decimal 1,000 GB figure.

How do I convert TB to GB?

Multiply the number of terabytes by 1,000 for decimal conversion: GB = TB × 1,000. For binary conversion, multiply terabytes (technically tebibytes) by 1,024: GiB = TiB × 1,024. Use the calculator above to convert instantly between both standards.

Why do manufacturers use 1000?

Storage manufacturers use the decimal (SI) standard because it’s the internationally standardized scientific unit system (consistent with kilometers, kilograms, etc.) and produces larger, cleaner marketing numbers. A “1 TB” drive sounds and measures better than the binary equivalent of “0.909 TiB.”

Why does Windows show different values?

Windows (and most operating systems) calculate storage using binary math (powers of 1,024) but display the binary unit names as if they were decimal (showing “GB” when it’s actually GiB). This creates the appearance of “missing” storage — a 1 TB drive (1,000,000,000,000 bytes) shows as approximately 931 GB in Windows, even though no actual storage is lost.

What is TiB?

TiB (tebibyte) is the official IEC binary unit equal to 1,024 GiB or 2^40 bytes (1,099,511,627,776 bytes). It was introduced in 1998 to distinguish binary storage measurements from decimal terabytes (TB), which equal 1,000 GB or 10^12 bytes. The “i” in TiB/GiB/MiB/KiB always indicates binary (1,024-based) measurement.

What is GiB?

GiB (gibibyte) is the IEC binary unit equal to 1,024 MiB or 2^30 bytes (1,073,741,824 bytes). It’s the binary equivalent of a gigabyte, used to accurately describe storage measured in powers of 1,024 — which is how computer memory and most operating system file size displays actually work internally.

Is this calculator accurate?

Yes — the calculator uses precise mathematical conversion factors for both decimal (1,000-based) and binary (1,024-based) standards, with JavaScript double-precision floating-point accuracy. Results are rounded to your selected decimal precision (2, 4, or 6 places). All conversion factors match official SI and IEC definitions.

Can I convert PB?

Yes — switch to “Full Converter” mode to see your input value expressed across the complete storage hierarchy: bits, bytes, KB, MB, GB, TB, and PB (petabytes). 1 PB = 1,000 TB = 1,000,000 GB under the decimal standard.

What is a byte?

A byte is the fundamental unit of digital storage, consisting of 8 bits. One byte can represent 256 distinct values (2^8) — enough to encode a single character in basic text encoding (like ASCII). All larger storage units (KB, MB, GB, TB) are built as multiples of bytes.

What is a bit?

A bit (binary digit) is the smallest unit of digital information, representing a single 0 or 1 value. Eight bits make one byte. Bits are typically used to measure data transfer speeds (Mbps, Gbps for internet/network speed) while bytes measure file sizes and storage capacity (MB, GB for files and drives).

Which storage standard should I use?

For comparing advertised product specifications (buying a drive, comparing cloud plans), use the decimal (SI) standard — this is what manufacturers and most pricing pages use. For understanding what your operating system displays as “available space,” remember it’s typically using binary (IEC) calculation, even though it may be labeled with decimal unit names like “GB.”

Why are SSD capacities different from what’s shown?

SSD and HDD capacities are always advertised using decimal units (1 TB = 1,000,000,000,000 bytes exactly). When you plug the drive in, your operating system calculates and displays free space using binary math, showing a smaller number (e.g., 931 GB instead of 1,000 GB) — this is a unit conversion display difference, not missing or defective storage. A small additional amount (1-3%) is also used by filesystem formatting overhead.

Can I compare storage devices?

Yes — after calculating your conversion, scroll to the “Compare Against Common Devices” section to see how your storage value compares to common device capacities like 512 GB SSDs, 1-4 TB drives, NAS systems, and enterprise storage arrays.

Can I estimate file sizes?

Yes — the “What This Storage Can Hold” section estimates how many photos, songs, HD movies, 4K videos, games, and documents your calculated storage capacity could theoretically store, based on typical average file sizes for each media type.

Is this calculator free?

Yes — this TB to GB calculator is completely free to use with no registration, no usage limits, and unlimited conversions. All calculations run instantly in your browser with no data sent to any server.

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