Updated: Apr 19, 2020
Here we have 6 common configurations with sofas, a modular lounge, chairs and a sofa with a chaise. As you can see the ottoman reflects the shape of the sofas, rectangle sofa and rectangle ottoman. The size of the ottoman is dictated purely by the size of your sofas and the size of the room. E.g. small sofas, small ottoman, large sofas, large ottoman. Nothing looks worse than a small sofa with a huge ottoman and also a large sofa with a small ottoman. Maybe a guide would be 2/3 of the length of the sofa. Plan out the size of your ottoman with markers on the floor. Walk around the proposed ottoman to feel how comfortable the size and shape will be. I typically use round ottomans with a single sofa from 2 seaters to a 4 seater, is I think that look works. Also as in example 6, a round ottoman is easier to walk around, and most importantly everyone can put their feet up. I am not a huge fan of the sofa with a chaise as in example 4, as only one person gets to lounge often creating undue wear and flattening the foam. An ottoman instead of a chaise would be able to move along the sofa to even outwear.