How to convert bytes to KB, MB and GB

Short answer

Divide by 1024 until the number becomes less than 1024, and move to the next unit each time:

const formatBytes = (bytes) => {
  const units = ['B', 'KB', 'MB', 'GB', 'TB'];
  let index = 0;
  while (bytes >= 1024 && index < units.length - 1) {
    bytes /= 1024;
    index++;
  }
  return `${Number(bytes.toFixed(1))} ${units[index]}`;
};
 
console.log(formatBytes(500));
console.log(formatBytes(1536));
console.log(formatBytes(5368709120));

Output:

500 B
1.5 KB
5 GB

With Intl.NumberFormat

Intl.NumberFormat knows units like kilobyte and megabyte and writes them in the right language:

const format = new Intl.NumberFormat('en-US', {
  style: 'unit',
  unit: 'megabyte',
  unitDisplay: 'short',
  maximumFractionDigits: 1,
});
 
console.log(format.format(3.456));

Output:

3.5 MB

Common mistake

toFixed() returns a string, and it keeps a zero at the end. Number() removes it:

console.log((2).toFixed(1), Number((2).toFixed(1)));

Output:

2.0 2

Thanks for reading!

Short answer

With Intl.NumberFormat

Common mistake

Functions used in this recipe

Thanks for reading!