My normal shoe size is between 7.5 and 8 it really depends on the style and the manufacturer.
As for Ecco, I would order 38 for sandals and 39 for boots and pumps, how I wish they carry half sizes.

This particular mary jane, it's made for narrow to medium size feet. This style has a low cut vamp that
shows a bit of toe cleavage.

Leather is soft enough to have a broken in feel, I can wear it right out of the box.
Nice low heels makes it comfortable to wear and dressy enough for skirts, with the double straps to keep your feet happy and sure-footed.

If I were to order a 38, it'd have been tight all over, this style definitely not good for medium to wide feet ladies.