New construction cost calculation, suitable for architect?

My initially requested general contractor has a price of €2,550 / sqm turnkey.

So, another €100/sqm on top for the floor coverings - turnkey preferably without coverings (except bathroom/kitchen).

Yes, floor coverings & interior painting/wallpapering work are missing there.

The architectural firm has confirmed the cost estimate again.
The €3,500 that are often mentioned here are more like sales prices including land, closing costs, profit margins, etc.

Yes, floor coverings & interior painter/wallpapering work are missing there.

So in the end 200€/sqm living space on top.

The 3,500€ that are often put forward here are more like sales prices including land, closing costs, profit margins, etc.

We are talking about +/- 3,000€/sqm

I wrote to you that my clients calculate with at least 3,500€/sqm WITHOUT land, profit, ancillary costs, etc., and actually pay that.
Current sales prices from a residential park developer operating in the low-price segment: 4,500€/sqm all-in including land (150-250sqm as special property – in other words, a condominium as a house with one heating system for the entire settlement). We are talking about eight construction projects distributed across Germany (not in metropolitan areas!) with soon 45,000sqm of living space. That is – for a low-price segment and serial construction – almost 30% above the values of your architect.

Better calculate with 3,000€/sqm and be happy if it gets cheaper.

What is your motive behind doubting the warnings given here (which after all do not come from envious and ignorant people): fear of unnecessarily playing it small if you turn them into cautious actions? What happens if the "that looks unbelievably cheap" faction is right, and the architect's estimates are exceeded: how many percent could you have to finance additionally without it hurting – ten yes, twelve yes, fifteen still yes? – or rather only three and with more then "Maria, you who are blessed ... make the hopeful calculation come true"?

2 GUs (well-established with many references) offer the construction for €2,550 and €2,650 / sqm respectively (turnkey) plus additional costs. The architect is also around this price.

Due to the direct border location to Luxembourg, we are neither in a socially weak nor low-demand region.

I do not doubt anything but am now extremely confused, since with a difference of €1,000/sqm, €150-200k easily add up. That breaks any refinancing, as the overall project is already seven-figure in the end.

Thanks for your input. I don’t need confirmation of my opinion but realistic values, which you also seem to provide. Still, I wonder where the approx. €1,000/sqm difference comes from.

Because building costs are the same everywhere; the land and additional costs vary.

Nevertheless, I wonder where the approx. 1000€/sqm difference comes from.

Don't ask yourself, ask the architect. I've already told you that.

Because building costs are the same everywhere,

No, that's not true. Building in Munich, for example, is more expensive than building in adW in MeckPom.

2 GCs (well-established with many references) offer the construction for 2,550€ and 2,650€/sqm respectively (turnkey)

With what equipment and quality? Any GC can give you such an offer – but then add-ons usually follow. And if you then add the floor coverings (160sqm at 100€ all in – with parquet or large-format tiles even more, including tiles, adhesive, substrate preparation, baseboards) and painting work (500sqm spackling, sanding, painter’s fleece, paint + similar treatment of ceilings – that can easily be 100€/sqm based on the living area), you might end up at around +/- 3,000€/sqm (with the second GC at 2,650€/sqm, that would be 2,850€/sqm and thus only 5% below the stated approx. 3,000€).