Knife Sharpener Angle Guide

Knife Sharpener Angle Guide

There are two certain rules in knife sharpening. On the one hand, the greater the angle, the higher the edge retention, but the worse the cutting performance. On the other hand, the lower the angle, the better the cutting performance, but the worse its edge retention.

Based on this, one can assume that there may be an average angle, which on the one hand will allow the blade to have good edge retention and good cutting qualities.

To find out for sure, one of the sharpening experts spent a lot of time testing the most realistic angles for practical use. The angles tested were 42, 36, and 30 full degrees. The angle value of 40 to 42 degrees is often used for mass-production knives.

The second was an angle of 30 full degrees, as the vast majority of kitchen chef knives today will have a similar value. Let this value be a certain risk point, where the cutting qualities are good enough and there is a risk of losing edge retention. 

The third angle is 36 full degrees. This is where a simple mathematical average value was chosen.

Experienced users know that there are knives for chopping nails and there are knives for cutting vegetables and no other way around. You have to understand that a really good cutting knife requires proper and careful use.

It is necessary to understand at what angle it is impossible to work with comfort with any kind of knife. It is also necessary to understand at what angle the knife can get serious damage, which, one way or another, will lead to serious sharpening work.

1. The concept of the sharpening angle

The sharpening angle is the value of the angle in degrees between the planes that form the cutting edge. The surfaces can be formed by one or two planes of the blade's secondary bevels and most often the full value of the sharpening angle is referred to when mentioning it. Further specification is required only when half of the sharpening angle is mentioned.

1 – width of blаde, 2 – spine, 3 – blade flat (plane), 4 – bevels, 5 – secondary bevels, 6 – TBE (thickness behind the edge)

1 – spine, 2 – sharpening angle, 3 – bevels, 4 – secondary bevel, 5 – cutting edge

The angle of sharpening for each knife type is chosen according to a set of different criteria, which may have different significance, but all influence the choice. Among them are the following points:

• knife purpose
• blade specifications
• the grade or standard of the steel and its hardness level
• features of use

Since all of these criteria are specific to each class of knife, it is necessary to go over each item individually to understand why a particular angle value should be set during sharpening.

The kitchen knife category, in terms of design and application, is one of the most extensive categories of knives, including a large number of different products. The most famous is probably the set of three chef's knives: a chef's or cook's knife, a universal knife for slicing, and a knife for vegetables.

Chef or chef's knife		Parameters
Technical Specifications	Blade length	18 – 20 cm
	Blade width (widest part)	about  4 – 5 cm
	Spine thickness	2 – 3 mm
	Type of bevels (possible)	from the spine; convex
	Type of tip	wedge-shape; drop
	Recommended sharpening angle, full	22°, 24° – 40°

Usually, a chef's knife is characterized by the length of the blade in the range of 18 - 22 centimeters and the spine thickness of about 2-3 millimeters. The blade has bevels from the spine and can be about 4 centimeters wide at its widest part. These sizes are quite common, but as we know, everyone is different and we have different palm sizes. For this reason, manufacturers offer slightly larger or smaller models of knives in order to make the work with medium and large foodstuffs as comfortable and efficient as possible.

When it comes to sharpening angles, they depend not only on the size of the knife but also on the steel grade or the standard and its hardness. It is widely believed that it is necessary to sharpen soft steels at larger angles in order to retain the sharpness of the edge, and harder steels at smaller angles. This is both right and wrong, as the plasticity of steel must be taken into account. Proper heat treatment, among other things, will ensure that the steel has the best possible qualities.

Previously, values around 40 degrees were considered standard, but now many kitchen knives, including those in the middle segment, are sharpened according to Asian standards and are often sharpened to 24 degrees, and sometimes even more acute angles like japanese knives.

Japanese santoku chef knives are very sharp and are becoming increasingly popular. These knives are sharpened to a very low angle and are used for slicing fish, meat, and vegetables.

Assuming that the manufacturing process of the steel was correct, if you are satisfied with the size of the blade and the handle fits well in your hand, do not hurry to resharpen the knife. The factory grinding of the knife will definitely serve you for some time, and you will understand the behavior of the steel and can decide whether you are satisfied with the results of the work or not.

Universal slicing knife		Parameters
Technical Specifications	Blade length	12 – 18 cm
	Blade width (widest part)	about 2 – 3 cm
	Spine thickness	2 – 3 mm
	Bevels type	from the spine; convex
	Tip type	wedge-like
	Recommended sharpening angle, full	24° – 40°

All of the above is also true for the universal knife. Despite the fact that the thickness of the spine and width of the blade is smaller, you can choose the sharpening angles according to the same recommendations as for a chef's knife.

Judging by the medium size of the knife and its name, we can assume its versatile use for food of different consistencies. If you have a set of three chef's knives from one manufacturer, one series, then you know exactly how the steel of your knives behaves. If you know the nature of the most common tasks, you can be sure which sharpening angle for the universal knife will be the best.

A vegetable knife, perhaps one of the smallest of all kitchen knives often used for peeling small-sized fruits and vegetables, completes the set of three chef's knives.

Vegetable knife		Parameters
Technical Specifications	Blade length	8 – 10 cm
	Blade width (widest part)	about 2 cm
	Spine thickness	1 – 2 mm
	Bevels type	from the spine; convex
	Tip type	wedge-like; drop; common
	Recommended sharpening angle, full	20° – 40°

Like other knives, which, in one way or another, are used for cutting various products, many people use this knife out of habit for peeling and slicing fruits and vegetables. Of course, there are other more convenient and effective tools for peeling fruits and vegetables, but after all, habit is second nature. For this reason, this type of knife is in the product range of all known manufacturers.

The choice of the sharpening angle can depend on the blade's size, the steel's characteristics, and your own preferences and purposes. The angle for this type of knife can range from 20 to about 35 full degrees.

Bread knife		Parameters
Technical Specifications	Blade length	20 –22 cm
	Blade width (widest part)	about 3 cm
	Spine thickness	about 2 mm
	Bevels type	from the spine; straight
	Tip type	drop
	Recommended sharpening angle, full	20° – 30°

A bread knife is an unusual tool among kitchen knives. Due to its wavy, large, and serrated cutting edge, the blade penetrates, especially well into fresh bread, much better than all other long-blade knives. The cutting-edge structure gives a well-controlled and convenient cutting. However, this does not mean that bread cannot be cut with another type of knife. Some experts recommend bread knives not only for cutting bread but for some other foods as well. For example, knives with thin, narrow blades can get stuck in large foods such as cabbage, pineapples, and watermelons. The difference will be quite noticeable if you cut them with a bread knife. An even bigger difference will be noticeable if the knife has convex bevels, but that is a whole other topic.

The overall advice that applies to this type of knife is related to its sharpening. Some well-known manufacturers of electric sharpeners wrongly believe that the bread knife should be sharpened just like other knives. It is a critical mistake to give out such information to users. These sharpeners only let you sharpen (and profile) bevels, which serrated bread knives do not have. Technically, they have bevels, but not where they can be reached by these sharpeners.

When slicing bread, the blade bites into the product with its teeth and cuts with the bevels, which are found in each little arch or groove between the teeth of the blade. If you sharpen such a knife with an electric sharpener, you just risk grinding off the teeth to the point where they just start to break off.

The process of sharpening such a knife is a very time-consuming task because each groove needs to be sharpened with a very small-diameter honing steel, from both sides. You may not want to do that, but this is the only proper way to do it.

Sharpening angles may range from 20 to 30 degrees, depending on the manufacturer. You can check this with a sharpie marker if you want to sharpen the knife yourself instead of buying a new one. However, we must say that it takes a lot of effort to blunt a serrated knife just by cutting bread on a cutting board.

Fillet knife		Parameters
Technical Specifications	Blade length	about 18 cm
	Blade width (widest part)	about 1,5 – 2 cm
	Spine thickness	about 1 – 2 cm
	Bevels type	wide bevels with secondary bevels; from the spine with secondary bevels; straight
	Tip type	basic
	Recommended sharpening angle, full	15° – 25°

Fillet knives are designed for cutting thin slices of meat, fish or poultry and for cutting meat off the bones and skin. The length of the blade can range from about 10-12 centimeters up to 30 centimeters. Whereas a length of about 18-19 centimeters is considered universal. The blades are made of bimetal stainless steel to maintain flexibility and sharpness.

A 15°-degree sharpening angle is considered suitable for soft foods such as unfrozen fish and meat, and an angle of about 25°-degrees is suitable for maintaining a stable cutting edge.

Boning knife for meat, fish and poultry		Parameters
Technical Specifications	Blade length	about 15 – 18 cm
	Blade width (widest part)	about 2 – 3 cm
	Spine thickness	about 2 mm
	Bevels type	wide bevels with secondary bevels; from the spine with bevels; straight
	Tip type	basic
	Recommended sharpening angle, full	25° – 30°

A boning knife is more or less similar to a fillet knife, but it is designed mainly for one of the stages of meat or poultry processing, as well as large fish, during which the skin, cords, and bones are separated from the flesh. If you do not do such tasks frequently, for example in the home kitchen, you can get by with a chef's knife or even a utility knife. Otherwise, a boning knife is essential for the cost-effective and high-quality processing of meat.

Carving knife (sporting, fish and meat cutting)		Parameters
Technical Specifications	Blade length	about 21-22 cm
	Blade width (widest part)	about 3 – 4 cm
	Spine thickness	about 1 – 2, rarely 3 mm
	Bevels type	straight; from the spine
	Tip type	wedge-like; basic
	Recommended sharpening angle, full	25° – 30°, rarely more than 30°

Carving knives are a special group of professional and household tools, specifically designed to work with chunks of meat of different sizes. This type of knife has several varieties with certain features, which are always taken into account when buying a knife for specific purposes. However, most often, when people speak of a carving knife, they mean a knife with relatively universal characteristics - with a wide strong blade with a length of up to 30 cm - used for cutting various products, including meat fillets. Such a knife has thin and flexible, wide at the base blade, noticeably narrowing towards the tip, it is used to separate the flesh from bones and allows penetration into any hard-to-reach places.

Steak and roast beef knife		Parameters
Technical Specifications	Blade length	about 13 cm
	Blade width (widest part)	about 1,5 – 2 cm
	Spine thickness	about 1 – 2 mm
	Bevels type	from the spine, straight
	Tip type	basic
	Cutting edge	serrated
	Recommended sharpening angle, full	25° – 30°

The so-called special kitchen knives have an average blade length of about 12 - 15 centimeters and have one characteristic feature - they all have a serrated cutting edge, which is much finer than the serrated edge of a bread knife and is quite safe to use.

The steak knife is basically a smaller version of a bread knife and is designed for easy cutting of meat products. It is recommended for use with a wooden board.

Knife for tomatoes, vegetables and greens		Parameters
Technical Specifications	Blade length	about 13 cm
	Blade width (widest part)	about 2 cm
	Spine thickness	about 1 mm
	Bevels type	from the spine
	Tip type	forked
	Cutting edge	serrated
	Recommended sharpening angle, full	20° – 30°

A tomato knife, or better-said vegetable knife, is mainly designed for slicing fruits and vegetables with thick skin and tender flesh. The serrations are capable of providing a precise and easy cut, while the forked tip allows you to lift and move the thin slices off the board. Cheap versions of the knife have a small, non-sharpenable serrated edge. The more expensive ones have a larger serrated edge, like the one on steak knives, and may have a single-side bevel. They are sharpened like bread knives.

Sandwich knife		Parameters
Technical Specifications	Blade length	about 12 cm
	Blade width (widest part)	about 1,5 – 2 cm
	Spine thickness	about 1 mm
	Bevels type	from the spine
	Tip type	no tip; rounded
	Cutting edge	with serrated parts
	Recommended sharpening angle, full	15° – 25°

A breakfast or sandwich knife is pretty much the same as a table knife, which also often has small serrated parts on the edge. In some ways, this type of knife resembles a steak knife, but without the tip. Cheaper versions are made of a very thin strip of metal and serrations are never sharpened. Some expansive branded models of this knife can be sharpened. 

Cheese knife		Parameters
Technical Specifications	Blade length	about 15 cm
	Blade width (widest part)	about 3 – 3,5 cm
	Spine thickness	about 1 – 2 mm
	Bevels type	from the spine with a wide bevel
	Tip type	forked
	Cutting edge	with serrated parts
	Recommended sharpening angle, full	20° – 25°

A cheese knife has holes in the blade, this way the blade cuts well into a viscous product and the serrated cutting edge easily separates the slices. If the cutting edge of the knife is as shown in the image above, the knife can be sharpened along the area of the bevel.

Kitchen cleaver / chopping knife		Parameters
Technical Specifications	Blade length	about 16 - 18 cm
	Blade width (widest part)	about 8 cm
	Spine thickness	about 4 – 5 mm
	Bevels type	wide bevels with secondary bevels; from the spine with secondary bevels; sometimes one-sided
	Tip type	no tip
	Cutting edge	45° – 55°, rarely up to 60°

Kitchen cleavers, despite their massive appearance, can have a very sharp cutting edge. Not only can they handle slicing and chopping vegetables, but with proper sharpening, they can even chop bones, depending on the weight of the object.

There is, of course, another group of kitchen knives or, more correctly, cutlery, but very few people would sharpen such items. The angles range from 55 to 60 degrees and they are used on a plate.

A general recommendation for all kitchen knives. 

Keep in mind that most kitchen knives, and especially chef knives, have a very small thickness behind the edge. If your knife has good flexibility and sufficient hardness, it can be sharpened at fairly low angles. With a small thickness behind the edge, the blade will cut with its geometry, not with the sharpening angle. For this reason, large angles may also be acceptable with a small thickness behind the edge. This is especially true in cases where the steel has a low level of hardening and may be susceptible to bending.

With a large thickness behind the edge (TBE), there is no point in setting large angles, as the TBE line can have a negative effect on the cutting efficiency.

When sharpening, the load on the knife blade in the form of contact with the kitchen board is often considered, which is subdivided into:

• controlled contact with angles less than 25°
• moderate contact with angles less than 35°
• secure contact with angles less than 45°
• unrestricted contact with angles greater than 45°

Pocket (folding) knives		Parameters
Technical Specifications	Blade length	about 6 – 11 cm
	Blade width (widest part)	about 1,5 – 3 cm
	Spine thickness	about 2 – 5 mm, rarely thicker than 5 mm
	Bevels type	straigth from the spine; hollow; convex
	Tip type	basic; wedge-like; bowie; or no tip
	Recommended sharpening angle, for sharpness	30° – 40°, sometimes less than 30°
	Recommended sharpening angle, for edge retention	35° – 45°, sometimes greater than 45°

Pocket folding knives represent a very significant part of the knife market and it is difficult to describe all possible designs and use cases. It should be noted, however, that such knives are used in a wide variety of ways, so the angle values can also be quite different.

There is one recommendation we can highlight, when you need sharpness, the blade can be sharpened between 30° and 40° degrees, and between 35° and 45° degrees when you need the cutting edge to retain its geometry. In both cases, you can set angles that will be slightly lower or higher depending on preference, type of tasks to be performed, characteristics of the blade and the knife as a whole.

Bushcraft and tourist knives		Parameters
Technical Specifications	Blade length	about 9,10 – 15 cm
	Blade width (widest part)	about 2,5 – 5 cm
	Spine thickness	about 3 – 5 mm, sometimes thicker than 5 mm
	Bevels type	straigth from the spine; wide bevels; hollow; convex; scandi
	Tip type	basic; wedge-like; bowie; or no tip
	Recommended sharpening angle, for sharpness	35° – 40°, sometimes lower than 30°
	Recommended sharpening angle, for edge retention	40° – 45°, for heavy tasks 45 – 55°

If we consider the characteristics of knives designed for wide range of tasks in the outdoors, we should note that in one way or another a large amount of woodworking and other rough work is expected. There are knives with scandi and convex bevels with a high level of retention of the cutting edge geometry.

A hunting knife category is a difficult market segment to describe due to the different traditions of different countries. One can often hear among many hunters around the world that the more experienced the hunter, the shorter his knife. The true professional will almost always use a fixed knife, as any folding knife is far less suitable for obvious reasons.

Bushcraft knife (for skinning)		Parameters
Technical Specifications	Blade length	about 5 – 12 cm
	Blade width (widest part)	about 3 – 4 cm
	Spine thickness	about 3 – 4 cm
	Bevels type	straigth from the spine; wide straight bevels; wide hollow; convex
	Tip type	trailing point; straight
	Recommended sharpening angle, for sharpness	20° – 25°, sometimes greater than 25°
	Recommended sharpening angle, for edge retention	30° – 45°

The main purpose of a hunting knife is to skin and carve game. The first stage of skinning requires a well-sharpened, non-flexible skinning knife with a raised, rounded tip, which will serve best for separating the skin from the meat. Skinning knives often have a hook pointed towards the handle, which is used to quickly cut the hide or open the belly.

The carcass-cutting process may require a more multi-purpose knife for the rough work, so as a rule the hunter should have two knives. Both knives should not be long, as the work focuses on the movement of the hand.

Everything else that is advertised and sold as hunting knives is more likely a wrongly advertised product or a product designed for a different purpose. Other knives may be carried when hunting, but that does not make them hunting knives.

There are items that belong to the category of cutting tools that can be sharpened, but are not as common as the knives described above. The following is a list with recommended sharpening angles:

• Hairdressing straight scissors 45 - 55 degrees;
• Hairdressing convex scissors 30 – 45 degrees;
• Household scissors 50 – 60 degrees;
• Dangerous razors 15 – 20 degrees;
• Wood chisel about 25 degrees;
• Axes about 25 – 35 degrees, for heavy work and chopping up to 45 degrees.

Summary

The choice of a sharpening angle is the decision of the user: if a sharp cutting edge is required, then one needs to choose a low angle, if there are no particular tasks or they are occasional, then greater angles are acceptable.

If you decide to create a secondary bevel and micro-secondary bevel, then you have to choose the angle for each individual knife and the type of work you want to do with each knife.

Always match the steel to the task, you can not make a tactical crowbar or a cutter out of a single type of steel by changing the hardness. Decreasing the hardness below the allowed limits does not give better ductility/strength values. As a result, performance can drop drastically.

It is also true that if the knife is sharpened at a lower angle, there will be less contact with the material and therefore less stress on the cutting edge. In other words, you should not pursue stability and forget such facts.

Cutting performance is linked directly to the quality of the cutting edge, which is determined by the angle of convergence of the planes of the bevels or secondary bevels. The correct sharpening angle must be chosen for each individual knife, depending on its intended use and the overall geometry of the blade. There are general recommendations for the choice of the sharpening angle, and there are no strict boundaries. A lot depends on the personal preferences of the owner.

The following general recommended angle values can be taken as a guide, depending on the purpose of the knife:

• Household kitchen knives with a priority for edge retention — 35–40 degrees
• Professional and specialised kitchen knives — 25–35 degrees
• Professional chef's knives — 20 – 25 degrees
• Tourist and hunting knives with a priority for sharpness — 30 – 35 degrees
• Tourist and hunting knives with a priority for edge retention — 40 – 45 degrees
• Pocket folding knives with a priority for sharpness — 30 – 40 degrees
• Pocket folding knives with a priority for edge retention — 40 – 45 degrees

In each case, the angles may deviate upwards or downwards, depending on the quality of the steel from which the blade is made. The methods of angle retention and its control are strongly related to the concept of the sharpening angle, and differ significantly between manual sharpening and the use of various units with angle control and abrasive guides with abrasive holders.