# Coding Challenge - #29: Format Byte Size

**URL:** <https://forum.kirupa.com/t/coding-challenge-29-format-byte-size/683624>\
**Category:** web dev\
**Created:** [October 8, 2026, 10:00pm UTC](https://forum.kirupa.com/t/coding-challenge-29-format-byte-size/683624 "2026-10-08T22:00:08Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![sarah\_connor](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.kirupa.com/sarah_connor/32/31258_2.png) [@sarah\_connor](https://forum.kirupa.com/u/sarah_connor)\
**Post date:** [October 8, 2026, 10:00pm UTC](https://forum.kirupa.com/t/coding-challenge-29-format-byte-size/683624/1 "2026-10-08T22:00:08Z")

</div>

Write a function `formatBytes(bytes)` that converts a non-negative integer number of bytes into a human-readable string using units `B`, `KB`, `MB`, or `GB` (base 1024). Values with units larger than `B` should be rounded to two decimal places, omitting trailing zeros if whole (e.g., `formatBytes(1536)` returns `'1.5 KB'`, `formatBytes(1048576)` returns `'1 MB'`, and `formatBytes(500)` returns `'500 B'`).

```js
function formatBytes(bytes) {
  // Your code here
}

```

**Rules:**

- Use 1024 as the byte conversion threshold.
- Do not display trailing zeros after decimal places (e.g. ‘1.5 KB’, not ‘1.50 KB’).
- Return ‘0 B’ when the input is 0.

Post your solution as a reply. Answer goes up in about a day.