Choose the actual size convention
- Enter a nonnegative data quantity and choose bits or the correct byte unit.
- Select a decimal or binary target unit explicitly.
- Convert and review the byte equivalent before copying or downloading.
Bits, bytes and two prefix systems
One byte (B) is 8 bits. Decimal prefixes use powers of 1000: 1 kB = 1000 B and 1 GB = 1,000,000,000 B. Binary prefixes use powers of 1024: 1 KiB = 1024 B and 1 GiB = 1,073,741,824 B. Consequently 1 GB is about 0.931323 GiB, and 1 MiB = 1.048576 MB.
The selectors use these explicit definitions from NIST’s binary-prefix guide. The calculation is quantity × source byte factor ÷ target byte factor. A display using “GB” to mean a binary quantity must be interpreted deliberately: choose GiB here if its actual definition is 2³⁰ bytes.
| Unit | Bytes per unit |
|---|---|
| Bits (bit) | 0.125 |
| Kilobits (kbit, decimal) | 125 |
| Megabits (Mbit, decimal) | 125000 |
| Gigabits (Gbit, decimal) | 125000000 |
| Bytes (B) | 1 |
| Kilobytes (kB, decimal) | 1000 |
| Megabytes (MB, decimal) | 1000000 |
| Gigabytes (GB, decimal) | 1000000000 |
| Terabytes (TB, decimal) | 1000000000000 |
| Petabytes (PB, decimal) | 1000000000000000 |
| Kibibytes (KiB, binary) | 1024 |
| Mebibytes (MiB, binary) | 1048576 |
| Gibibytes (GiB, binary) | 1073741824 |
| Tebibytes (TiB, binary) | 1099511627776 |
| Pebibytes (PiB, binary) | 1125899906842624 |
| Terabits (Tbit, decimal) | 125000000000 |
| Petabits (Pbit, decimal) | 125000000000000 |
| Kibibits (Kibit, binary) | 128 |
| Mebibits (Mibit, binary) | 131072 |
| Gibibits (Gibit, binary) | 134217728 |
| Tebibits (Tibit, binary) | 137438953472 |
| Pebibits (Pibit, binary) | 140737488355328 |
Limits and privacy
Nonnegative source values up to 10¹⁵. Fractional quantities are allowed as mathematical conversions; files use whole-byte counts, and this tool does not round up storage allocation. Large results beyond JavaScript’s safe-integer range may lose individual-byte precision. Display uses up to 12 significant digits and six decimal places or scientific notation; CSV retains the floating-point result, not arbitrary-precision integers.
This converts quantities, not transfer rates, download time, compression ratio, disk formatting overhead or usable-device capacity. The optional file picker reads only the byte-count metadata, not file contents; nothing is uploaded. Entered values stay in browser memory without saved sizes or external conversion requests. The 22 named choices cover decimal bits/bytes and binary bits/bytes through peta/pebi. Live conversion waits 300 ms, and the all-units CSV covers every supported choice. Swap preserves the entered number; result reuse preserves the unrounded quantity and reverses direction. Those actions, examples, file-size selection and Reset offer one Undo step. Editing inputs discards that action history. Reset clears output and restores 1 GB to GiB. File-size selection keeps the chosen target unit and switches the source to bytes; cancellation preserves the current conversion.
Does the smaller GiB number mean bytes disappeared?
No. One GiB is a larger unit than one GB. Changing the unit changes the number representing the same byte quantity; filesystem overhead is a separate issue.