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Storage Converter and Calculator Guide
This storage converter and calculator converts between bits, bytes, decimal storage units such as GB and TB, and binary IEC units such as GiB and TiB. It also estimates how many files fit on a drive and explains why an advertised 1 TB drive may appear as roughly 931 GiB in software.
Every conversion uses the exact bit count as its common base. That avoids the common mistake of treating GB and GiB as interchangeable. Decimal units use powers of 1,000, while binary units use powers of 1,024. They describe the same data with differently sized units.
Decimal GB vs Binary GiB
Storage manufacturers normally label drive capacity with decimal SI prefixes: 1 GB is 1,000,000,000 bytes and 1 TB is 1,000,000,000,000 bytes. Binary IEC prefixes are based on powers of two: 1 GiB is 1,073,741,824 bytes and 1 TiB is 1,099,511,627,776 bytes.
Because a GiB is larger than a GB, the numeric GiB value is lower even though the byte count has not changed. Formatting, partitions, recovery areas, filesystem metadata, snapshots, and reserved space can reduce usable capacity further. For authoritative definitions, see the NIST SI units information and the IEC binary-prefix guide.
| Unit | System | Exact bytes |
|---|---|---|
| 1 MB | Decimal | 1,000,000 |
| 1 MiB | Binary | 1,048,576 |
| 1 GB | Decimal | 1,000,000,000 |
| 1 GiB | Binary | 1,073,741,824 |
| 1 TB | Decimal | 1,000,000,000,000 |
| 1 TiB | Binary | 1,099,511,627,776 |
How to Estimate How Many Files Fit
The file-capacity mode subtracts your chosen reserve percentage, divides the remaining capacity by the average file size, and rounds down to a whole-file count. Rounding down matters because a partial file does not fit. The result also reports used and remaining storage so the estimate is auditable.
Treat presets as planning assumptions, not guarantees. Photos vary with resolution and compression; video varies with bitrate, codec, frame rate, and duration; games change with updates and downloadable content. For video planning, use the video bitrate calculator. To estimate transfer time after sizing the data, use the bandwidth calculator.
Choosing the Right Storage Unit
Use bits when working with low-level data sizes or network rates, and use bytes when working with files and drives. A network connection advertised in Mbps is measured in megabits per second, while a download is commonly reported in MB. Dividing the bit rate by eight gives the theoretical byte rate before protocol overhead and other practical limits.
Use decimal units when matching a storage vendor label, cloud-storage quota, or other specification that explicitly follows SI prefixes. Use binary IEC units when software reports KiB, MiB, GiB, or TiB. If a program displays GB but calculates with powers of 1,024, the label is ambiguous; compare its reported exact byte count whenever possible.
For capacity planning, leave a realistic reserve instead of targeting a completely full device. Operating systems and applications may need free space for temporary data, updates, caching, and maintenance. SSD performance and endurance behavior can also change as free space becomes scarce, so the theoretical maximum file count is not always the best operational target.
Related Computer Tools
Storage planning often connects to hardware endurance and number-system work. Estimate write endurance with the SSD lifespan estimator, or inspect low-level values with the binary to decimal converter and decimal to binary converter.
Frequently Asked Questions
Is 1 GB equal to 1,000 MB or 1,024 MB?
Under decimal SI definitions, 1 GB equals 1,000 MB. The binary relationship is 1 GiB equals 1,024 MiB, so using the correct symbols prevents ambiguity.
Why does a 1 TB drive show less space?
A 1 TB drive contains one trillion advertised bytes, which is about 931 GiB when expressed in binary units. Formatting, partitions, recovery data, and filesystem overhead can reduce the available amount further.
How many bytes are in a gigabyte?
One decimal gigabyte contains exactly 1,000,000,000 bytes. One binary gibibyte contains exactly 1,073,741,824 bytes.
Are bits and bytes the same?
No. One byte contains eight bits, and the capitalization matters: lowercase b means bit while uppercase B means byte.
How accurate is the files-fit estimate?
The arithmetic is exact for the values entered, and the count always rounds down to whole files. Real capacity can differ because file sizes vary and filesystems consume additional space.
What reserve percentage should I use?
Use the percentage that matches your planning needs and operating environment. Keeping free space can leave room for updates, temporary files, snapshots, and normal system operation.