What Is a 70/30 Asymmetric Bevel? (Angle Chart)

A 70/30 asymmetric bevel has about 70% of its bevel width on one blade face and 30% on the other. It does not mean sharpening at 70° and 30°, and the ratio does not set the sharpening angles. For a kitchen knife, choose practical per-side angles based on the blade, steel, and task, while keeping its existing asymmetry.

A durable edge depends on matching its shape to the knife and how you use it. Sharpen too steeply for the steel, and the edge may chip; change the bevels without care, and the knife may steer as it cuts. The labels and angle numbers can be confusing, so start by separating two things: bevel width and sharpening angle.

This is a guide to knife-edge geometry, not cookware. Terms such as induction compatibility and oven ratings do not apply. I use the chart below as a set of starting points, then check the maker’s guidance and the knife’s cutting behavior.

What a 70/30 Asymmetric Bevel Means

A 70/30 bevel describes the approximate share of bevel width on each face of the blade. One face has the larger bevel, and the other has the smaller one. This ratio describes the bevel’s shape; it does not tell you the edge’s sharpening angles or prescribe a particular angle pair.

The blade faces are the two broad sides of the knife. A bevel is the sloped strip of metal that leads from a face toward the cutting edge. On an asymmetric bevel, those strips are not equal in width.

For example, if the visible bevel widths add up to 10 mm, a 70/30 split would be about 7 mm on one face and 3 mm on the other. That example describes width only. It does not mean the edge is sharpened at 70 degrees on one side and 30 degrees on the other.

The bevel-width split and the sharpening angle are separate measurements. Blade geometry affects how they relate, so the ratio alone cannot reveal the right angle. A knife may also have a small secondary bevel, sometimes called a microbevel, at the edge. That narrow strip can make visual estimates harder.

Keep track of which face has the larger bevel. Reversing the large and small bevels can change how the blade moves through food. Check the maker’s description when available, especially if you are unsure which side is intended to face your dominant hand.

Angle Chart for a 70/30 Kitchen Knife

This chart gives practical starting angles for each side, measured from the blade face to the stone. The larger-bevel side is sharpened first in each pair. These are not a conversion from a 70/30 width ratio; use the maker’s angle guidance if it is available.

The included angle is the sum of the two per-side angles in this chart. For example, 12° plus 18° gives an approximate 30° included angle. It is a useful way to compare the pairs, but it does not describe bevel width.

A lower angle makes a more acute edge, which can cut with less resistance but may be less durable. A higher angle generally supports the edge more, though it may feel less keen. Steel hardness, edge thickness, and the work the knife does all matter. The chart is a starting point, not a guarantee of performance.

If your knife is very thin or made from hard, brittle steel, do not assume that the sharpest possible angle is the best choice. If you do not know the steel or the original angles, begin conservatively and test the result before removing more metal.

Identify the Bevel and Prepare the Knife

Before sharpening, find the larger bevel, check the edge for damage, and look for the maker’s instructions. A stable stone or guided sharpener helps you repeat an angle, while a clean, dry work area reduces slips. Preparation protects both the intended geometry and the knife’s edge.

Use good light to inspect both faces from heel to tip. Look for a wider sloped area on one side, chips, and uneven wear. A felt-tip marker on the bevel can help: a few light passes on a stone show whether you are contacting the area you intend to sharpen.

Then choose a suitable whetstone or guided sharpener and secure it so it cannot slide. Follow the stone maker’s directions for soaking or wetting; some stones need water, while others have different care instructions. Keep a towel nearby, and handle the knife by its handle.

Before you begin, note:

• Which face has the larger bevel
• Whether the knife maker lists a side or angle specification
• Where the edge is chipped, rolled, or uneven
• Which angle pair from the chart is a reasonable starting point

Small chips or a badly damaged edge may need more metal removal than routine sharpening. If you are unsure how much to remove, or the knife has a specialized grind, consider a qualified sharpener rather than changing the geometry by trial and error.

Choose Angles and Sharpen Each Face

Sharpen the larger-bevel face at your chosen starting angle until a consistent burr forms along the edge. Then refine the opposite face at its selected angle with fewer strokes. Use light, controlled pressure throughout; the goal is to restore the edge without erasing the blade’s asymmetry.

A burr is a thin wire of metal pushed to the opposite side of the edge during sharpening. It is a useful sign that your sharpening strokes have reached the edge, but it should not be left in place. Work along the full blade length and check that the burr forms consistently rather than at just one section.

For a whetstone, keep the blade steady and use a repeatable stroke. If you use a guided sharpener, set each side to the selected angle rather than assuming the tool will preserve the 70/30 width ratio on its own. A guide controls angle; it does not automatically set bevel width.

A careful sequence is:

1. Set the large-bevel angle. Use the chart as a starting point, or follow the maker’s specification.
2. Sharpen the large-bevel face. Use controlled, light strokes until you can feel a consistent burr on the opposite side. Check along the edge with care.
3. Set the small-bevel angle. Use the second angle in your selected pair. Avoid widening this bevel by making repeated, unnecessary passes.
4. Sharpen the small-bevel face. Use fewer strokes, then alternate very light strokes to reduce and remove the burr.
5. Check the full edge. If a section still feels dull, return to that area with the same angle and light pressure instead of increasing force.

Equal angles on both sides can change the knife’s original geometry. So can aggressively widening the smaller bevel. Either change may affect how the knife tracks through food. A very acute edge may also chip, particularly on hard or brittle steel. If the edge chips in use, the angle may be too low for the knife’s steel or task; seek maker guidance before removing more metal.

Deburr, Clean, and Maintain the Edge

Deburring removes the thin wire of metal left after sharpening. A clean edge is less likely to feel rough or catch during a cut. Finish with light alternating strokes, then rinse and dry the knife promptly. Clean and dry the stone according to its instructions so both tools are ready for their next use.

Do not use heavy pressure to tear off a burr. That can damage the edge you have just formed. Instead, make very light strokes on each face at the same angles, alternating sides. Check the edge carefully; avoid running a finger along it.

After sharpening, rinse the blade and dry it with a towel. Clean the stone as its maker directs, since stone care varies. Store the knife where the edge cannot hit a hard surface, such as loose utensils in a drawer. Contact with hard material can damage a fine edge.

If the knife loses sharpness quickly, first review how you use and store it. Cutting on a hard surface or scraping with the edge can wear or damage it. Repeatedly sharpening the smaller-bevel face is not a safe shortcut; inspect the geometry before making further changes.

Test Cutting Performance and Present Food Cleanly

A sharp edge should cut food in a controlled way, but a paper test alone cannot show how the knife behaves in a real cut. Test on food that suits the knife, such as a tomato or an onion, and notice whether the blade tracks straight or pulls to one side. Use those results to guide small adjustments.

Try a gentle, controlled cut rather than forcing the blade. If it pulls consistently, check that you preserved the large and small bevels on their intended faces and used the selected angles. Also consider the food and cutting method: a cut made at an angle can feel different from a straight downward cut.

A clean cut through delicate food can be a useful sign that the edge is working well. But do not judge the bevel ratio by cut quality alone. A knife can cut well with several edge geometries, and the right choice depends on its design and use. If it tracks poorly after sharpening, pause before removing more metal; check the maker’s guidance or consult a skilled sharpener.

Practical 70/30 Sharpening Scenarios

These scenarios show how to use the chart without treating it as a fixed rule. Each one starts with the knife’s existing geometry, then chooses a reasonable angle pair for the intended work. They are examples, not claims that all knives of a given type require the same angles.

In the first scenario, a fine slicer used for careful cuts may suit the 10°/15° starting pair. If the edge chips, stop using it for demanding work and check the maker’s advice. Do not keep lowering the angle in pursuit of a sharper feel.

For a general-purpose knife, 12°/18° offers a practical starting point from the chart. If the blade cuts cleanly and the edge holds up, there may be no reason to alter the angles. For tougher use, the 15°/20° pair gives a less acute starting geometry, but it is still subject to the knife maker’s specifications and the steel’s limits.

FAQ: 70/30 Asymmetric Bevels

These quick answers clarify what the ratio means, how the angle chart works, and what to check when sharpening. The key distinction is that bevel width and edge angle are different measurements. Keep the knife’s existing asymmetry unless its maker or a qualified sharpener recommends a change.

Does 70/30 mean 70° on one side and 30° on the other?
No. It describes the approximate distribution of bevel width between the two blade faces, not sharpening angles.

What angle should I use for a 70/30 knife?
There is no single angle set by the ratio. The chart’s pairs are practical starting points; use the maker’s specification when available.

Are the chart angles measured per side?
Yes. Each number is the angle for one face, measured from the blade face to the stone. The included angle is the sum of the two numbers.

Which side should I sharpen first?
Start with the face that has the larger bevel. Keep track of its position and follow the maker’s guidance if you can find it.

Can I sharpen both sides at the same angle?
That can change the intended asymmetry and may affect how the knife cuts. Avoid doing so unless the maker recommends it.

How do I know when I have sharpened enough?
Look for a consistent burr along the edge after working the larger-bevel face. Then sharpen the opposite face with fewer strokes and remove the burr with light alternating strokes.

Can a low sharpening angle cause chips?
Yes. An overly acute edge may chip, especially on hard or brittle steel. Choose angles based on steel, edge thickness, and use.

Should I make the small bevel wider?
Not without checking the edge geometry and maker’s guidance. Repeated sharpening on that face can erase the intended asymmetry.

Is a paper test enough to judge the edge?
No. Paper can show basic sharpness, but test cutting on suitable food to assess control and tracking.

What should I do if the knife steers after sharpening?
Stop removing metal. Check that you kept the larger and smaller bevels on their original faces and used the selected angles. If the problem remains, consult the maker or a qualified sharpener.

Key Takeaway

A 70/30 bevel is a width ratio, not an angle prescription. Identify which face has the larger bevel, choose a suitable starting pair, and sharpen with light, controlled strokes. Preserve the knife’s intended asymmetry, remove the burr, and judge the result with careful food cuts rather than the ratio alone.

(This article was written by one of our staff writers, Julian R. Hayes. Visit our Meet the Team page.)