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Bits & Bytes Converter - Base 2 and Base 10 Calculator

Convert data units, file sizes, and network speeds (Mbps, MB/s) locally in the browser.

Decimal Units (Base 10 / Metric)

Binary Units (Base 2)

How it works

This tool converts instantly between bits, bytes and every common multiple, both decimal (KB, MB, GB, TB) and binary (KiB, MiB, GiB, TiB). Type a value in any field and the rest update live. Everything runs locally in your browser.

KB vs. KiB: decimal vs. binary

Decimal units use powers of 1000 (1 KB = 1000 bytes), while binary units use powers of 1024 (1 KiB = 1024 bytes). Storage makers advertise in decimal, so a "1 TB" drive holds about 931 GiB as your operating system counts it. Network speeds are usually in bits per second, not bytes, so divide by 8 to compare with file sizes.

About this tool

The byte converter converts between bytes, kilobytes, megabytes, gigabytes, terabytes and petabytes, both in SI form (base 1000: KB, MB, GB) and IEC form (base 1024: KiB, MiB, GiB). Useful for understanding file sizes, computing bandwidth, planning disk space, or comparing what your OS shows to what the manufacturer advertises. Windows still displays "GB" but really means "GiB", which is why a "1 TB" disk shows as about 931 GB when new. The tool makes it trivial to convert both ways and see both interpretations side by side.

How to use it

  1. Enter the value you know (e.g. 500 MB).
  2. The tool instantly shows the value in every other unit.
  3. Check both the SI column (1000-based) and the IEC column (1024-based).
  4. Use bytes as the source of truth if you need exact counts.

Examples

1 GB in everything
Input1 GB
OutputSI: 1 000 000 000 bytes IEC: 0.9313 GiB = 953.67 MiB
1 TB disk
Input1 TB (as sold by the manufacturer)
OutputWindows shows: 931.32 GB (which is really 931.32 GiB)
Disk manufacturers use SI (1 TB = 10^12 bytes). Windows uses IEC internally but writes "GB", hence the gap.
Download at 100 Mbit/s
Input100 Mbit/s
Output12.5 MB/s = approx. 45 GB/h
Network speeds are quoted in bits per second (b), file sizes in bytes per second (B). 1 byte = 8 bits.

Common use cases

  • Check if a video fits on a USB stick before transfer.
  • Compute monthly data usage against your mobile quota.
  • Plan backup storage for many VMs or databases.
  • Convert between network measurements (Mbps) and file sizes (MB).
  • Understand why a "250 GB SSD" shows about 232 GiB of free space.

Frequently asked questions

What is the difference between KB and KiB?
KB (kilobyte) is the SI unit, 1000 bytes. KiB (kibibyte) is the IEC unit, 1024 bytes. The gap grows exponentially: 1 TB = 1 000 000 000 000 bytes, 1 TiB = 1 099 511 627 776 bytes, about 10 % more.
Why does Windows still use the old labels?
Historically everyone used 1024 and called it "KB". When IEC standardised KiB/MiB/GiB in 1998, Linux and macOS (partially) followed, but Microsoft kept the old practice for backwards compatibility. This causes confusion every time someone buys a new disk.
What about bits vs bytes?
1 byte = 8 bits. Network speeds are usually in bits per second (Mb/s or Mbps, lowercase b), while file sizes and storage speeds are in bytes per second (MB/s, uppercase B). A 100 Mbps line therefore tops out at 12.5 MB/s under ideal conditions.
What comes after petabyte?
After peta (PB) comes exa (EB), zetta (ZB), yotta (YB), ronna (RB) and quetta (QB). The last two were added to SI in 2022. Ronna is 10^27 bytes; the whole internet’s combined storage is estimated to have just crossed 1 ZB.

Technical background

Historically 1 KB = 1024 bytes because it aligns with memory addressing (2^10). When hard disks began to be measured in thousand-million bytes instead of 1024^3, confusion followed, and in 1998 the IEC standardised new prefixes for binary powers: kibi (Ki = 2^10), mebi (Mi = 2^20), gibi (Gi = 2^30), tebi (Ti = 2^40), pebi (Pi = 2^50), exbi (Ei = 2^60). The SI prefixes kilo, mega, giga etc. are strictly base 1000, as SI requires. In practice both are still used depending on context: network speeds and RAM are quoted in binary, disks and file transfers usually in decimal for marketing reasons, while filesystems and OSes mix the two. Bit vs byte is a separate source of error: 1 byte is 8 bits in all modern systems (historically 6-, 7- and 9-bit bytes existed), the abbreviation "b" = bit, "B" = byte. The converter handles all cases including bit/s ↔ byte/s with correct division by 8.