File Size Formatter API

About the File Size Formatter API

A file size formatter API for turning raw byte counts into labels people can read. Send a number of bytes and get back a formatted string such as "1.5 GiB", along with the numeric value, the unit it chose and the standard it used. It handles everyday conversions like bytes to MB or bytes to GB, in binary (MiB, GiB) or decimal (MB, GB) units, so a storage dashboard and a download page can each show the convention their users expect.

Typical uses are upload limits, disk usage reports, backup summaries and file listings where the database stores bytes but the interface needs KB, MB or GB. You can let the API pick the largest unit that keeps the value at 1 or above, or ask for a specific unit, and set how many decimal places to show.

The Free plan returns the formatted string, value, unit, standard and precision. Paid plans add a conversions object with the same byte count expressed in every unit from bytes to yottabytes, which saves a second call when a table needs several columns.

How it works

The divisor depends on standard: binary (the default) divides by 1024 and labels units B, KiB, MiB, GiB, TiB, PiB, EiB, ZiB and YiB; any other value, including decimal, divides by 1000 and labels them B, KB, MB, GB, TB, PB, EB, ZB and YB. For every unit the API computes bytes / divisor^n and rounds it to precision decimal places with toFixed, then parses it back to a number, so trailing zeros are dropped: 1073741824 bytes gives value: 1, not 1.00.

When unit is not set, the API walks from the largest unit down and picks the first whose value is 1 or more. Values under 1 byte stay in B. When unit is set, it is matched case-insensitively against the label list of the chosen standard; a label that does not belong to that standard (for example MB with standard=binary) is not found, and the auto-selected unit is used instead without an error. formatted is value and unit joined by a space.

precision defaults to 2. Because rounding happens per unit, small results in large units round to 0, which is why a 1 GiB input shows TiB: 0 in conversions. The conversions object is keyed by the labels of the active standard and is returned as null on the Free plan.

What people use it for

File Management

Display file sizes in user-friendly formats in file managers and storage applications

Storage Analytics

Format storage usage data in dashboards and analytics reports

Data Transfer

Show download and upload sizes in appropriate units during file transfers

API Responses

Convert byte sizes to readable formats in API responses and data exports

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON

Default REST response

XML

Markup format

YAML

Human-readable

CSV

Tabular export

Beta

GraphQL

Query language

New

MCP

For AI agents

Request parameters — GET /v1/filesizeformatter

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

Optional

1
2

curl "https://api.apiverve.com/v1/filesizeformatter?bytes=1073741824&unit=GB&precision=2&standard=binary" \
  -H "x-api-key: YOUR_API_KEY"

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Response — GET /v1/filesizeformatter

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

{
  "status": "ok",
  "error": null,
  "data": {
    "bytes": 1073741824,
    "formatted": "1 GiB",
    "value": 1,
    "unit": "GiB",
    "standard": "binary",
    "precision": 2,
    "conversions": {
      "B": 1073741824,
      "KiB": 1048576,
      "MiB": 1024,
      "GiB": 1,
      "TiB": 0,
      "PiB": 0,
      "EiB": 0,
      "ZiB": 0,
      "YiB": 0
    }
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

What a call costs — 1 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Zero-code embed — one snippet, no backend

Drop an interactive File Size Formatter form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.

Changelog — File Size Formatter API

Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.

Currently v1