If you only remember one number: 20 degrees per side is the safe default for most Western kitchen knives and general-purpose blades. It offers a durable edge that resists chipping and holds up to regular board contact. But 20° is not universal. A Japanese gyuto at 20° is a waste of good steel. A meat cleaver at 15° will chip the first time it meets bone. The “best” angle depends on three factors: what the knife is made of, what you cut with it, and how you treat it. This guide breaks down the specific angles for every common knife type, explains the sharpness-versus-durability trade-off in plain terms, and clears up the measurement confusion that trips up most beginners.