Mark its widest point
Lay out a circle of the proposed size on the floor. Check the passage where the diameter is widest. Compared with an equally wide square, a circle leaves more room at diagonal corners, yet can project just as far into the tightest part of the route.
Compare a smaller rectangle or oval too. The better answer depends on the sofa, seating positions and circulation. If the table must constantly move sideways, its size or location may be the problem rather than its shape alone.
Check reach from the sofa
On a long sofa, the centre of a round table is not equally close to every seat. Sit at the outer positions and test reaching the top. A small additional surface at one end may help, but needs its own purpose and unobstructed position.
Consider height and the base. A central pedestal allows different foot movement from several legs near the edge. A broad base under a small top may take more room than a photograph suggests. Include the whole construction in the comparison.
Try the intended contents
Lay out the usual objects within the circle: a book, remote control and perhaps a tray. A round top provides less continuous depth towards its edges than a rectangle. A large rectangular tray may therefore overhang even if its width initially appears compatible.
Keep enough clear surface for objects to stand securely. If decoration occupies most of the top, the table functions more as an obstacle than an accessible surface. A rounded edge is also no reason to reduce circulation space or assume the furniture cannot cause an injury.
Repeat the trial with any recliner open or footstool in use. A round table is not automatically easier to move aside. That depends on weight, suitable lifting points and a reachable alternative position. Shape is one part of the layout, not a replacement for adequate movement space.
