The conditions are a two-story house from 1978 with a brick facade on a wooden frame and lightweight beams as the intermediate floor. ~80m2 per floor (approx. 8x10m).
I would like to open up the kitchen and living room on the ground floor (ground level), but the wall is load-bearing. The thing is that the ridge runs parallel to the load-bearing wall on the ground floor, but there are no load-bearing interior walls on the upper floor (nor are there any walls directly above the load-bearing wall on the lower floor). The opening will be about 3 meters (from the exterior wall to the stud just to the right of the doorway):
It may be that I am stating the obvious here, but how does one correctly size the beam that should replace the wall section? I guess that the load-bearing wall is meant to prevent the floor on the upper floor from sagging, rather than to support the weight of a snow-laden roof. Can one rely on online calculation tools and sizing tables, or is this clearly a situation where hiring a structural engineer to calculate it is the right choice?