code: public function getSizeLimit()
      {
          // Get the lowest between post_max_size and upload_max_filesize, log a warning if the first is < than the latter
          $limit = $this->sizeToBytes(ini_get('upload_max_filesize'));
          $postLimit = $this->sizeToBytes(ini_get('post_max_size'));
          if ($postLimit > 0 && $postLimit < $limit) {
              Yii::warning('PHP.ini\'s \'post_max_size\' is less than \'upload_max_filesize\'.', __METHOD__);
              $limit = $postLimit;
          }
          if ($this->maxSize !== null && $limit > 0 && $this->maxSize < $limit) {
              $limit = $this->maxSize;
          }
          if (isset($_POST['MAX_FILE_SIZE']) && $_POST['MAX_FILE_SIZE'] > 0 && $_POST['MAX_FILE_SIZE'] < $limit) {
              $limit = (int) $_POST['MAX_FILE_SIZE'];
          }
  
          return $limit;
      }
docs: Returns the maximum size allowed for uploaded files.
  
  This is determined based on four factors:
  
  - 'upload_max_filesize' in php.ini
  - 'post_max_size' in php.ini
  - 'MAX_FILE_SIZE' hidden field
  - [[maxSize]]
  
  @return int the size limit for uploaded files.