Additional cost for tile installation 80x80 cm

"Format" as such is first and foremost absolute – you also have to be able to put it into the appropriate scale. That means: a large absolute format without also being generous with the dimensions of other elements / distances / passage widths can relatively shift the scale so that the overall composition looks the opposite of generous.

Anyone who does not want to "consistently" afford the 120 cm stair width (or 30 cm more passage width between dining table and sideboard) or still only plans for 95 cm clear internal width of the guest WC should reconsider 80 cm edge length for the floor tiles in my opinion. Otherwise, the large checkered pattern easily backfires.

Basically, you are right.

We have 120x120 cm tiles, but also a living/dining room of almost 55 sqm. The tiles really look good there. But they also come into their own in the hallway with a width of 155 cm.

And with our stairs at 115 cm, it had the advantage that we don't have joints on each tread and riser, and to top it off, our tiler didn’t install a bulky metal strip but a very delicate one. It looks great.

Regarding the installation price: Our tiler installs from 80x80 cm tiles with 2 men. And he also applies adhesive onto the tile.
In this respect, I see the surcharge as justified.

I installed ours together with him and thus saved the second man. With our tile size that was a tough job, and after the first day in the evening I had muscle pains I never knew before. But the effort was worth it.

Here is a longer thread, also with pictures:

60% surcharge just because of the more difficult installation?

It's not just about laying the tiles, the substrate also has to be leveled much more precisely, so the preparation is also more complex. Breakage always affects a larger piece and so on. That adds up.