The best backrest angle for a comfortable dining chair is usually a slight backward recline, often around 5 to 10 degrees from vertical. This gives enough support to avoid stiffness while keeping you upright for eating and conversation. If the backrest is too straight, the chair may feel rigid. If it leans too far back, you may need to reach forward toward the table. Seat depth, cushion firmness, and backrest shape also matter. A comfortable dining chair should support your back while keeping you naturally close to the table.