Jeremias Märki - 2014-04-14

I'm sorry for the late answer. I'm not checking the mail account where this came in very often lately. Please take a look at There are two major problems with the generator URLs you posted:

  • "mw=0.3" was specified which won't produce consistent bar widths at 120 dpi. Following the troubleshooting page, you should specify "mw=0.01666in" which is equivalent to 2 / 120 = 0.01666. "2" because that makes the narrow bar exactly 2 pixels wide which is probably best since the human-readable part is relatively long in your case.
  • Don't use JPG as output format. It's a lossy image format and barcode readers love maximum contrast. PNG is much much better for barcodes in general. So, I suggest you do "fmt=png"