The Martin Visser sofas or those who look like those, are around 1.90 meters wide and 80 cm deep. Furniture fabric on the other hand is generally 1.40 m wide. However, you do not want a seam in the middle of the seat. You want a nice, modern sofa. Then pay attention when you buy upholstery fabric. You then use the fabric across. If there is a pile in the fabric then that is not handy for these sofas. Your fabric will then wear out sooner by using the fabric differently than what it was made for.
And it won’t happen that often, but if you think of flowers or stripes for your fabric for this sofa, you get either a seam in the middle or the flowers and the stripes are pointing in the wrong direction. All in all you need approximately 4.5 meters of fabric.
An explanation here. I hope you get it. My drawing is not as good as the upholstery.
So 3 cm around the frame, 10 cm fort he side and 1.90 mtr for the top makes:
3+3+10+10+1.90 = 2.16 mtr. And double that. One time fort he seating and one time fort he backrest.
The depth of the seat is 80 cm the foam 10 and 3 around makes: 80+10+10+3+3=1.06 mtr. And the fabric is only 1.40 mtr wide
Time to start watching that video about stitching the corners.
You can switch the subtitles on and of with the wheel at the right corners in the video.