Sofa seat depth significantly impacts comfort and ergonomic support; depths between twenty two and twenty five inches typically suit most adults. A well-proportioned seat depth encourages proper posture and long-lasting usability. Styles should prioritize this functional dimension over merely aesthetic appeal. Test seats by sitting to confirm comfort before buying. A supportive sofa that fits your body enhances enjoyment and encourages longer use, making seat depth a core factor when selecting a sofa size and style combination.