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Data Storage Converter
Convert between bits, bytes, SI units (KB/MB/GB) and IEC binary units (KiB/MiB/GiB). Click any result card to use it as the new input.
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💡 SI vs IEC
SI (Decimal): 1 KB = 1,000 bytes (hard drives, SSDs, network)
IEC (Binary): 1 KiB = 1,024 bytes (RAM, OS file sizes)
⚠️ A "500 GB" hard drive = ~465 GiB — this is why your OS shows less space!
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Base Units
SI — Decimal (powers of 1,000)
IEC — Binary (powers of 1,024)
Click any card to update the "To unit" and recalculate.
SI vs IEC Comparison for Your Value
The same data expressed in both systems — this explains the "missing space" on hard drives.
SI (Decimal, ×1000)
IEC (Binary, ×1024)
In perspective
Conversion Details
Via bits (base unit)
Why one value converts to two different answers
Internally every entry is reduced to bits, which act as a common base, and then expanded into the target unit. A byte is defined as 8 bits. From there the two families diverge. SI decimal units follow powers of ten, so a kilobyte is 10 to the power of 3 bytes, a megabyte 10 to the power of 6, a gigabyte 10 to the power of 9, a terabyte 10 to the power of 12 and a petabyte 10 to the power of 15. IEC binary units follow powers of two, so a kibibyte is 2 to the power of 10 bytes, which is 1,024, a mebibyte 2 to the power of 20, a gibibyte 2 to the power of 30, a tebibyte 2 to the power of 40 and a pebibyte 2 to the power of 50.
The conversion is therefore value multiplied by the source unit's bit weight, divided by the target unit's bit weight. The tool displays that ratio explicitly, for example 1 GB equals 0.931323 GiB, so you can see exactly which definition produced the number rather than guessing which convention a piece of software used.
The conversion is therefore value multiplied by the source unit's bit weight, divided by the target unit's bit weight. The tool displays that ratio explicitly, for example 1 GB equals 0.931323 GiB, so you can see exactly which definition produced the number rather than guessing which convention a piece of software used.
Worked example: a 500 GB drive in Windows
Enter 500, set the source unit to GB and the target to GiB. In SI terms, 500 GB is 500 x 10 to the power of 9 bytes, which is 500,000,000,000 bytes. A gibibyte is 1,073,741,824 bytes. Dividing gives 465.661 GiB.
That single calculation explains a complaint as old as hard drives. The manufacturer sells the drive as 500 GB because it genuinely holds 500 billion bytes. Windows reports free space using binary units but labels them GB, so the same drive appears as roughly 466 GB in File Explorer. Nothing is missing; the two numbers are measuring in different bases. macOS and most Linux file managers use decimal units, which is why the same drive reads closer to 500 there.
The gap widens as capacity grows because the ratio compounds. A 1 TB drive is 0.9095 TiB, showing as about 931 GB, and a 4 TB drive loses roughly 363 GB of apparent capacity to the same arithmetic.
That single calculation explains a complaint as old as hard drives. The manufacturer sells the drive as 500 GB because it genuinely holds 500 billion bytes. Windows reports free space using binary units but labels them GB, so the same drive appears as roughly 466 GB in File Explorer. Nothing is missing; the two numbers are measuring in different bases. macOS and most Linux file managers use decimal units, which is why the same drive reads closer to 500 there.
The gap widens as capacity grows because the ratio compounds. A 1 TB drive is 0.9095 TiB, showing as about 931 GB, and a 4 TB drive loses roughly 363 GB of apparent capacity to the same arithmetic.
Choosing the right unit for the job
Use decimal SI units for storage capacity quoted by manufacturers, for cloud storage tiers and for most data transfer allowances, since these industries advertise in powers of ten. Use binary IEC units when working with memory, file sizes reported by operating systems, block sizes and anything measured by the system itself, because those are addressed in powers of two.
The bigger trap is bits versus bytes. Network and broadband speeds are quoted in bits per second, while file sizes are in bytes, and the difference is a factor of eight. A 100 Mbps connection transfers at most about 12.5 MB per second before protocol overhead, so a 1 GB download takes around 80 seconds at best, not ten.
Watch the capitalisation as well: a capital B means bytes and a lowercase b means bits, so MB and Mb differ eightfold. Where precision matters, quote the byte count in full rather than relying on a unit label that different tools interpret differently.
The bigger trap is bits versus bytes. Network and broadband speeds are quoted in bits per second, while file sizes are in bytes, and the difference is a factor of eight. A 100 Mbps connection transfers at most about 12.5 MB per second before protocol overhead, so a 1 GB download takes around 80 seconds at best, not ten.
Watch the capitalisation as well: a capital B means bytes and a lowercase b means bits, so MB and Mb differ eightfold. Where precision matters, quote the byte count in full rather than relying on a unit label that different tools interpret differently.
Frequently Asked Questions
Strictly, 1 GB equals 1,000 MB under the SI decimal definition used by storage manufacturers and standards bodies. The 1,024 figure belongs to the gibibyte, written GiB. Many operating systems still label binary quantities as GB, which is why both numbers circulate for the same unit.
The drive holds 1 trillion bytes, which is genuinely 1 TB in decimal units. Windows divides by 1,024 three times to reach 931.32, then labels the result GB rather than GiB. No capacity is lost; the operating system is simply reporting tebibytes and gibibytes under decimal names.
A capital B means bytes and a lowercase b means bits, and there are 8 bits in a byte. So 1 MB is 8 Mb. Internet speeds are advertised in megabits per second while downloads are measured in megabytes, which is why a 100 Mbps line delivers about 12.5 MB per second.
They are the IEC binary units introduced to remove ambiguity from kilobyte, megabyte and gigabyte. A kibibyte is 1,024 bytes, a mebibyte 1,048,576 bytes and a gibibyte 1,073,741,824 bytes. Their symbols are KiB, MiB and GiB. Memory modules and operating system reports are naturally expressed in these units.
It depends entirely on encoding, so treat any figure as approximate. A 1 GB allowance holds roughly 250 smartphone photos at 4 MB each, about 200 songs at 5 MB, or around ten minutes of 4K video. Convert your actual average file size with the tool for a figure that matches your own files.