You may have noticed that you are given the option to select a 'format' for a shipment when selecting a service, this is because upon choosing a format you are including the dimensions you setup within the Whistl advanced settings.
There are 4 formats currently available to use for Whistl and these pull their dimensions from the Whistl advanced settings, found by clicking the cog icon in the bottom left corner of the Whistl settings page.
- Small Parcel
- Large Parcel
if you have any questions about this, feel free to contact support who will be happy to help