# Data size converter

> How much data is that in other units? Convert between bytes, kilobytes, megabytes, gigabytes, MiB, GiB and bits, with 1,000 and 1,024 kept apart.

Convert bits, bytes, kB, MB, GB, TB (base 1000) and KiB, MiB, GiB, TiB (base 1024). See why a 1 TB drive shows less on your computer.

- Page: https://how.box/conversion/data-size/
- Runs entirely in the browser.

## Inputs

Answer link: https://how.box/conversion/data-size/?v={v}&from={from}&to={to}

- `v` (number 0 to 1e15): The data size to convert, in the from unit. Example: `1`.
- `from` (bit, byte, kb, mb, gb, tb, kib, mib, gib, tib, kbit, mbit or gbit): Unit of v (unit id: bit, byte, kb, mb, gb, tb, kib, mib, gib, tib, kbit, mbit, gbit). Example: `gb`.
- `to` (bit, byte, kb, mb, gb, tb, kib, mib, gib, tib, kbit, mbit or gbit): Unit to convert to (unit id). Example: `mb`.

Example answer: https://how.box/conversion/data-size/?v=1&from=gb&to=mb

A complete link carries the primary answer in the page HTML; a missing or invalid value shows the default page.

## Agent tools

- `data_size_convert`: Converts a data size between units using exact definitions (1 byte = 8 bits; SI decimal kB, MB, GB, TB = 10^3, 10^6, 10^9, 10^12 bytes; IEC binary KiB, MiB, GiB, TiB = 2^10, 2^20, 2^30, 2^40 bytes; kbit, Mbit, Gbit = 10^3, 10^6, 10^9 bits; BIPM SI Brochure, IEC 80000-13).
  - MCP, one POST to https://how.box/mcp: `{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"data_size_convert","arguments":{"value":1,"from_unit":"gb","to_unit":"mb"}}}`
  - GET: https://how.box/mcp/run/data_size_convert?value=1&from_unit=gb&to_unit=mb

## How it works

Every unit is converted through bytes. A byte is 8 bits. The prefixes kilo, mega, giga and tera mean powers of 1,000: a gigabyte (GB) is 1,000,000,000 bytes. The binary prefixes kibi, mebi, gibi and tebi mean powers of 1,024: a gibibyte (GiB) is 2³⁰ = 1,073,741,824 bytes. So 1 GB is about 0.9313 GiB.

Drive makers use the 1,000-based units, so a 1 TB disk holds 1,000,000,000,000 bytes. Some operating systems count in 1,024s but still write GB, so the same disk shows about 931 “GB”, which is really 931 GiB. Nothing is missing.

The decimal prefixes come from the BIPM SI Brochure and the binary prefixes from IEC 80000-13, listed by NIST. Bit units (kbit, Mbit, Gbit) are 1,000-based, as network speeds use.

## FAQ

**Is a kilobyte 1,000 or 1,024 bytes?**
By the standard, a kilobyte (kB) is 1,000 bytes and a kibibyte (KiB) is 1,024 bytes. Older software often used “KB” for 1,024.

**Why does my 1 TB drive show 931 GB?**
The maker counts 1 TB as 10¹² bytes. The computer divides by 1,024³ and still calls the result GB, giving about 931. It is really 931 GiB.

**How many MB are in a GB?**
1,000 MB in a gigabyte, and 1,024 MiB in a gibibyte.

**How many bits are in a byte?**
8 bits. Network speeds are in bits per second, files in bytes, so divide by 8: 100 Mbit is 12.5 MB.

**Does this calculate download time?**
No. It converts data amounts. Download time also needs a transfer rate, and real transfers include overhead and interruptions.

More: [HowToolbox index](https://how.box/llms.txt) · [agent guide](https://how.box/agents.md) · [agent terms](https://how.box/about/agents/)