Storage Size Calculator
Convert digital storage sizes between bytes, KB, MB, GB, TB, and PB in one click. Enter a value and unit, switch between decimal (1000-based) and binary (1024-based) bases, and instantly see the equivalent in every unit. Perfect for working out how big a file really is, why a 1 TB drive shows as 931 GB, or how much space a backup, dataset, or download will take.
ToolsSoup's Storage Size Calculator converts any digital storage size between bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes in an instant. Type a value, pick its unit, and choose decimal (1000-based) or binary (1024-based) counting to see the equivalent in every other unit at once. It's the fastest way to make sense of file sizes, plan disk and backup space, and understand why advertised drive capacities never quite match what your computer reports. Everything runs in your browser: no uploads, no sign-up, and your numbers never leave your device.
What is a storage size calculator?
A storage size calculator converts a quantity of digital data from one unit to another — for example, turning 5,000 megabytes into gigabytes, or 0.5 terabytes into bytes. Storage is measured in bytes, and each larger unit (KB, MB, GB, TB, PB) is a power of a base unit above it. The catch is that there are two common bases: decimal, where each step is 1,000 (used by hard-drive and SSD makers), and binary, where each step is 1,024 (used by operating systems and memory). This calculator handles both, so you can convert a value and immediately compare how it looks under each system.
How to use the storage size calculator
Converting a storage size takes just a couple of steps, and the results update as you type:
- Enter the amount of storage you want to convert.
- Choose the unit it's currently in — bytes, KB, MB, GB, TB, or PB.
- Pick decimal (1000) or binary (1024) depending on whether you're matching a drive spec or your operating system.
- Read the equivalent value in every unit, then copy the results if you need them.
Decimal vs binary: KB vs KiB
Decimal units count in powers of 1,000: 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, and so on. This is the SI standard and what storage manufacturers print on the box. Binary units count in powers of 1,024 — strictly these are the kibibyte (KiB), mebibyte (MiB) and gibibyte (GiB), but Windows and many tools still label them KB, MB, and GB. Because 1,024 is larger than 1,000, the same number of bytes shows as a smaller figure in binary units, which is why disk reports look 'smaller' than the advertised size. Switch the base toggle to see your value both ways.
Why does my hard drive show less space than advertised?
Drive makers use decimal units, so a '1 TB' drive holds 1,000,000,000,000 bytes. Operating systems like Windows divide by 1,024 at each step, so that same drive reports as about 931 GB — the bytes haven't changed, only the unit the number is shown in. macOS and Linux typically use decimal units, so they show closer to the labeled capacity. Enter 1 TB in decimal here and switch to binary to see exactly where the missing-looking space goes.
Why use this storage size calculator?
- Converts between bytes, KB, MB, GB, TB, and PB all at once.
- Switches between decimal (1000) and binary (1024) counting with one click.
- Explains why a 1 TB drive shows as roughly 931 GB on your computer.
- Updates live as you type and lets you copy every result in one go.
- Runs entirely in your browser — free, no ads, and your numbers never leave your device.
Frequently asked questions
How many bytes are in a kilobyte?
It depends on the base. In decimal (SI) terms, 1 kilobyte is 1,000 bytes. In binary terms — strictly a kibibyte — it's 1,024 bytes. Storage makers use 1,000; most operating systems use 1,024. Use the base toggle above to convert either way.
What's the difference between decimal and binary storage units?
Decimal units step by 1,000 (1 KB = 1,000 B, 1 MB = 1,000 KB), matching the SI standard used on drive labels. Binary units step by 1,024 (1 KiB = 1,024 B), matching how memory and many operating systems count. The same number of bytes looks slightly smaller in binary units because 1,024 is bigger than 1,000.
Why does a 1 TB drive show as 931 GB?
The drive maker counts 1 TB as 1,000,000,000,000 bytes (decimal). Windows divides by 1,024 three times to get gigabytes, which gives about 931 GB. No space is lost — it's the same bytes shown in a different unit. Enter 1 TB in decimal and switch to binary to see it for yourself.
How many MB are in a GB?
In decimal there are 1,000 MB in a GB; in binary there are 1,024 MB in a GB. So a 4 GB file is 4,000 MB by drive-maker counting or 4,096 MB by operating-system counting. Pick the base that matches the figure you're comparing against.
Does this calculator handle very large or very small sizes?
Yes. It converts everything from single bytes up to petabytes, and switches to scientific notation for extreme values so the figures stay readable. Just enter the value and unit and read the equivalents.