Misago/frontend/src/utils/file-size.js

export default function(bytes) {
  if (bytes > 1000 * 1000 * 1000) {
    return (Math.round(bytes * 100 / (1000 * 1000 * 1000)) / 100) + ' GB';
  } else if (bytes > 1000 * 1000) {
    return (Math.round(bytes * 100 / (1000 * 1000)) / 100) + ' MB';
  } else if (bytes > 1000) {
    return (Math.round(bytes * 100 / 1000) / 100) + ' KB';
  } else {
    return (Math.round(bytes * 100) / 100) + ' B';
  }
}