Edge & Blade Geometry

Knife geometry determines how a blade moves through food. It’s shaped by two main elements: the way the blade is formed and the way the edge is sharpened.

Blade geometry in double-bevel knives refers to how the knife tapers from the spine down to the cutting edge. This includes different grind styles—like full flat, half flat, hollow, and S-grinds—as well as whether that taper is even or offset from side to side.

Edge geometry refers to how the cutting edge is applied. On double-bevel knives, the edge is sharpened on both sides—either evenly for a balanced, ambidextrous feel, or unevenly for a more directional cutting experience. When sharpened unevenly, the edge becomes hand-specific, favoring either right- or left-handed use.

Single-bevel knives use a different blade and edge geometry system altogether. Instead of tapering from both sides, the blade is primarily shaped from one side, with a wide bevel on the front and a slightly concave back. This creates a more aggressive taper and highly precise cutting performance, but also makes the knife specific to right- or left-handed use.

Understanding how blade geometry and edge geometry work together gives you more control over how a knife performs—and how it feels in use.

Symmetrical double-bevel knives have an edge that is ground on both sides of the blade forming a 50:50 symmetrical V-shape. Commonly, German cutlery have thicker blades and are manufactured with edges which are ground at 18° to 22°, although up to 30 degrees is established on Meat Cleavers. A broader edge is stronger, which is important when hammering strikes are used toward bone and the cutting board. Generally, Japanese knives are thin in comparison to German and come with edges ground at 15° to 18°.

Asymmetrical double-bevel edges are most common to Japanese cutlery and are offset accordingly to right- or left-handedness. Often, it is up to the user to establish an offset edge after they purchase the knife. Some Japanese manufacturers understand that chefs have their own edge and sharpening preferences. They purposefully give the purchaser a head start by favoring the grind (cutting edge), usually on the right side of the knife. Additionally, there is a Japanese blade geometry called Ryouba, 両刃. This means that the taper is only on the face of the knife as opposed to both sides. And, the back side is flat. There are three variations of the Ryouba; Full Flat-Ground, Half-Flat Ground, and Curved. Offset bevels are accomplished through percentages, not degrees. Users determine their offset preferences. Common ratios are 70:30, 80:20, or 90:10. Remember, offset edges require matching degrees from side to side, typically 15° to 18°, but are ground more on one side than the other.

Koba, 小刃, is a style that most manufacturers apply to their single-bevel knives. This essentially puts a micro-bevel at the cutting edge. It’s up to the user of the knife to continue following this technique when resharpening or choose to change to another style. Koba offers a good balance between sharpness and strength.

Hiratogi, 平研ぎ, offers the finest edge. It is very sharp, but more fragile. Commonly applied to slicing knives such as Yanagis, Takohikis, & Kiritsukes. Hiratogi is typically applied by the user of the knife once purchased, but sometimes can be applied by the retail shop that sells it (more common in Japan.) This essentially puts a final edge on the knife, referred to as “Honbadzuke”, which when translated means ‘sharpening to a sharper state’.

Hamaguriba, 蛤, makes for a very strong edge and helps to prevent chipping. It is named after a clam, referencing the clam shell’s rounded shape. This curvature is stronger, which helps strengthen the single-bevel’s inherent fragility. The trade-off is that the edge is less acute, rendering it less sharp. Typically applied to fish butchery knives like the Deba.