Our tests have shown some quality loss when using the online tool. The 320×50 format is too small for an ideal optimization. However, we have kept this format available for those who, through their creativity, are able to come up with unique concepts and can thus use the “upload your creative” option.
Even if the 320×50 format offers some visibility on mobile, please note that the publishers are also increasingly using the following formats on mobile pages:
- 300 x 250
- 300 x 600