My parcel is within 50dm3. Is a surcharge applied anyway?

The packaging dimensions communicated are internal dimensions, meaning you still need to add on the sides in order to get the outer dimensions. The external dimensions are measured during the sorting process, and any surcharges are calculated based on those dimensions. We recommend always measuring the outer dimensions when calculating whether the packaging falls within the permitted dimensions. 

It is also important to pack the parcel as compactly as possible, seal the packaging firmly and tightly and fill up the inner packaging well. This retains the shape of the box and keeps the dimensions of the box as close as possible to how it is sent.