Free File Size Converter calculator with clear step-by-step results.
File size conversion has two answers because there are two conventions. Operating systems and tooling generally report binary multiples of 1024, while drive manufacturers and network speeds use decimal multiples of 1000. The gap compounds with each step: it is 2.4% at the kilobyte and about 9.95% at the terabyte, which is exactly why a 1 TB drive shows as roughly 931 GB. Both results are shown so you can see which convention a figure came from.
To bytes
Bytes = value × base^(exponent of source unit)
To target unit
Result = bytes ÷ base^(exponent of target unit)
Reported sizes also depend on filesystem block size and metadata, so on-disk usage can exceed the logical file size shown here.
The manufacturer counts 1 TB as 1,000,000,000,000 bytes; the operating system divides by 1024 three times and calls the result GB. The same bytes, two conventions — nothing is missing.
They are the unambiguous binary units defined by IEC: 1 KiB = 1024 bytes. KB strictly means 1000 bytes under SI, but is very widely used to mean 1024, which is why selecting the base explicitly matters.
Binary for RAM, file sizes reported by your OS and most software tooling. Decimal for storage device capacity, bandwidth and anything quoted by a vendor or ISP.