Question about Really Useful Box Storage box

Hello ! How long is the bottom of the box? I'd like to store objects 45 cm long and they really need to lie flat at the bottom, not diagonally or rest on the sloping part. An answer below says that the inside length is only 38 cm, but knowing that the outside dimension is 48, I find it very surprising that 10 cm is lost through the walls, it seems to me that this is really a lot. Can anyone confirm this? Thank you!