From which size will a surcharge be applied for a letterbox parcel?

The minimum and maximum size and weight of a letterbox parcel are:

PostNL
Min. size: 14 x 9 cm
Max. size: 38 x 26.5 x 3.2 cm
Max. weight: 2 kg

DHL
Min. size: 15 x 11 x 1 cm
Max. size: 38 x 26.5 x 3.2 cm
Max. weight: 1 kg

DPD
Min. size: None
Max. size: 38 x 26 x 3 cm
Max. weight: 1 kg

If a letterbox parcel is larger than the maximum size and/or heavier than indicated above, the carrier will apply a surcharge.