How thick should a knife edge be? The answer is as important as finding the ideal edge angle. Together, edge thickness and angle determine edge retention, edge strength, and cutting ability. Things like steel type and hardness contribute relatively little to these factors.
How to Measure Edge Thickness
First, we need to understand where the cutting edge (also called a “secondary bevel” or “apex”) ends, and the primary bevel of a knife begins.
This is illustrated below:
The secondary bevel forms a triangle along the bottom of the blade. Half of that triangle is highlighted in red, above. The base of this triangle is formed where the secondary bevel ends, and the primary bevel begins.
The width of the triangle’s base is what we must measure to determine edge thickness.
Finding the base of the apex is easy on a knife: Its ground and polished, and often more reflective than the rest of the blade. Measuring edge thickness is easy, too. You just need a pair of digital calipers.
Place the end of the calipers right at the base of the bevel to measure the edge’s thickness.
What’s The Ideal Edge Thickness For a Knife?
Determing the best edge thickness for any knife depends on a few factors:
- What type of grind does the blade have?
- What’s the current edge angle on the apex?
- How thick is the rest of the blade, up to the spine?
- What type of knife is it? EDC pocket knife? Filet knife? Fixed chopper?
Those first two factors — grind and angle — matter most. If the knife in question has a high hollow grind and thin spine, then it’s probably destined for kitchen duty and delicate cutting. A thin edge will complement its performance and blade shape.
But if the knife in question is a Bowie or camp knife, then it probably has a wide flat or saber grind and thick spine. This type of knife favors edge strength over fine cutting, so a thick apex that can handle higher force will complement its intended use.
Here are guidelines for what edge thickness is best for various knives:
Straight Razor: 0.010″ to 0.012″ (0.25mm to 0.3mm)
A straight razor cuts the most delicately and requires virtually no force to shave. So, the most thin — and delicate — edge is ideal. Generally, an edge that’s 0.01″ or 0.25mm thick is the absolute thinnest edge you want put on a knife.
Any thinner edge will result in chipping and damage almost immediately, even with light cutting.
Carving or Filet Knife: 0.013″ to 0.016″ (0.33m to 0.41mm)
An edge this thin can handle at least some minor force. It’ll cut through raw meat and filet very fine slices while retaining cutting power for quite a long while.
Care should be taken to avoid striking an edge this thin on a cutting board or hard countertop, as it can still chip easily.
Pocket Knife or EDC Knife: 0.017″ to 0.024″ (0.43mm to 0.61mm)
Most 4″ and shorter blades, and most folding pocket knives tend have edges this thick. They can handle light strikes and can cut through stiffer materials, like cardboard, rubber, and cable.
Tactical Knife, Fixed Blade: 0.025″ to 0.029″ (0.64mm to 0.73mm)
Larger blades intended for field duty and heavy, indiscriminate cutting tend to have edge thicknesses in this range. These knives can typically baton wood and stab without risk of damage to the edge or tip.
High sharpness is still easily achieved, but push-cutting through paper and shaving becomes a challenge.
Camp Knives, Axes and Hatchets: 0.030″+ ( 0.76mm+)
At this edge thickness, a blade is likely to be a dedicated chopper or wood cutter. Most blades with an apex this thick have a wide flat, convex, Scandinavian, or shallow saber grind.
Obtaining high sharpness requires extensive grinding and honing with low- to high-grit sharpening stones.
What Else Affects an Edge’s Strength?
Edge thickness is just one factor that determines how well a knife cuts (or doesn’t cut). Learn about the other factors that impact overall performance: