SANTOKU
SANTOKU
Updated August 2026 · 5 min read · UK Japanese knife specialists
In short
The Rockwell C scale (HRC) measures a steel’s resistance to indentation — how hard it is, not how strong or how tough. A diamond cone is pressed into the steel under a set load and the depth of the dent gives the number. For kitchen knives it predicts edge retention: harder steel holds a keen edge longer but chips more easily. European knives typically sit at 55–57 HRC; Japanese-steel knives, including our VG10 and AUS-10 blades, run at roughly 58–62 HRC.
| HRC | What it means in a kitchen knife | Typical of |
|---|---|---|
| Below 54 | Dulls quickly, needs frequent honing | Budget stamped knives |
| 55–57 | Tough and forgiving, softer edge | German and other European knives |
| 58–62 | The kitchen sweet spot: long edge retention, still practical | Japanese-steel knives (VG10, AUS-10) |
| 63+ | Exceptional edge holding, increasingly brittle and hard to sharpen | Specialist and single-bevel blades |
When you are buying kitchen knives, and other items made from metal, you may have been confronted with details about the Rockwell hardness scale. But what does this mean? It’s certainly something that can leave even the most adept chefs scratching their heads, but there’s no need to worry. Once you understand it, the Rockwell hardness scale can help you in choosing the right knife for your needs.
In this guide, we’ll be getting better acquainted with the scale and giving you the lowdown on how to use it to your advantage when shopping for knives.
So What Does the Rockwell Hardness Scale Measure?
The Rockwell hardness testing method was developed by a man named Stanley P. Rockwell back in the early 1900s. It is, in the most simple terms, a measure of a steel’s resistance to indentation — its hardness. Hardness is not the same as strength, and it is not the same as toughness: a harder steel holds an edge longer but is more likely to chip. The number a steel is given can then be used to compare one blade with another on that one specific property.
The way that a Rockwell rating is arrived at is by putting the material under test and pressing a hard indenter into it under a controlled load. The indenter leaves a dent, and the measurement that matters is how deep that dent still is once the load has been taken away.
How the Rockwell test actually works
- Apply the minor preload. A small initial force seats the indenter against the steel and settles the surface, and this position is taken as the zero datum.
- Apply the major load. A much larger force is added and held for a set dwell time, pushing the indenter further into the material.
- Release the major load. The major force is removed while the minor preload stays applied, so the metal’s elastic springback is allowed to recover.
- Measure the residual depth. The permanent depth left behind, measured against the datum from step one, is converted into the Rockwell number — a deeper dent means a lower number and a softer steel.
While there are different versions of the Rockwell test, for hardened knife steel it is usually the case that a cone-shaped piece of diamond is used as the indenter. The hardness number is determined by the difference between the two depth measurements rather than by the size of the dent as seen from above, which is why the test works on medium case hardened steel, deep case hardened steel and shallow case hardened steel alike, including relatively thin sections.
Is There Any Other Way of Measuring Steel Hardness?
Most manufacturers will supply you with a rating based on the test we described above, but the Rockwell hardness test is by no means the only method of hardness testing. Rockwell itself is not one scale either — it is a family of scales, each pairing a particular indenter with a particular load, and each identified by a letter.
The ones you are most likely to see quoted are HRA, HRB and HRC. HRA and HRC both use the diamond cone but at different loads; HRB uses a hardened ball and is intended for softer metals such as annealed steel and brass. The scales, their indenters, their loads and the procedure itself are all defined in ASTM E18, the standard test method for Rockwell hardness of metallic materials. When shopping for knives you’ll almost always find that the Rockwell C scale has been used, which is why knife hardness is written as “HRC”.
What Does the Rockwell Hardness Test Tell Me About My Kitchen Knives?
When you are buying kitchen knives, the HRC figure is worth understanding because it tells you how well the steel resists being permanently deformed — and by extension, how long a finely ground edge will keep cutting before it rolls or dulls. It does not tell you the knife is “stronger”, and it does not tell you the knife is tougher; if anything, the harder the steel, the less forgiving it tends to be.
While it may feel a little alien when you are first getting to grips with the scale, what you really need to know are the important numbers. Knives with an HRC rating lower than 52 would be far too soft and it’s unlikely you’d ever see anything this low in a kitchen. That level is usually reserved for impact-cutting tools like the axe, where absorbing a blow matters far more than holding a keen edge.
If you’re looking at an affordable kitchen knife then the HRC might be lower, around 54 — still usable, but it will dull quickly and need honing often. For a Japanese-style blade we would look for 58 HRC or above, because that is where the difference in edge retention becomes genuinely noticeable in everyday cooking.
Broadly, kitchen knives live between roughly 55 and 62 HRC, while specialist blades — including many single-bevel Japanese-style knives — are taken to around 63 to 65 HRC. Going higher is not automatically better. As hardness climbs, the steel becomes more brittle, so the edge is likelier to chip on bone, frozen food or a hard board, and it takes longer to sharpen. That trade-off is exactly what we cover in our guide to whether hard blades chip easily. It’s all about finding that sweet spot.
How to Find the Sweet Spot
What you must understand when buying a knife is that you cannot have the best of everything. A knife cannot be hard, tough and flexible all in one. But when making knives, the manufacturer will try to find a sweet spot that perfectly balances between a higher HRC and a lower one. This allows for good edge retention while ensuring that the knife isn’t too brittle.
It is worth being clear about where that hardness actually comes from. Carbon content sets the potential hardness of a steel; the heat treatment — quenching and then tempering — determines what the finished blade actually reaches. Two blades cut from the same bar of steel can end up several points apart on the HRC scale purely because they were hardened and tempered differently. Other elements such as manganese, chromium and vanadium change how the steel behaves as well — chromium is the reason VG10 and AUS-10 are stainless rather than plain carbon steels, while vanadium refines the grain and helps the edge stay fine.
Harder knives are favoured by chefs looking for a very thin blade whose cutting edge is fine and sharp. However, this comes at a cost, so you’ll have to be willing to make something of an investment. You should also keep in mind that these blades, while they do stay sharp for longer, will require more effort and time on the stone when they finally do need sharpening.
What Hardness Are Our Knives?
We publish the number rather than leaving you to guess. Our blades are made from Japanese VG10 and AUS-10 steel and run at roughly 58–62 HRC — hard enough to hold a keen edge through a week of real cooking, not so hard that ordinary board work chips them. They are double bevel, ground at about 15° per side, and they are high-carbon stainless steels, not plain carbon steel, so they will not rust the moment you leave them wet on the board.
Aiko Black Damascus — VG10 core, from £64.99 · ★ 4.94 (120)
Haruta 8" Gyuto — VG10, £89.99 · ★ 4.87 (111)
Whetstone 400/1000 3000/8000 — hard steel needs a stone, £59.99 · ★ 4.86 (118)
Hard Japanese steel, honestly specified.
Shop Damascus knives →Rockwell Hardness FAQ
What does HRC mean on a knife?
HRC stands for Hardness Rockwell C, the scale used for hardened steels. A diamond cone is pressed into the steel under a set load and the depth of the resulting indentation gives the number. It measures resistance to indentation, not strength or toughness.
What is a good Rockwell hardness for a kitchen knife?
For a Japanese-style kitchen knife, roughly 58 to 62 HRC is the sweet spot: long edge retention while still being practical to sharpen. European knives usually sit around 55 to 57 HRC, which is softer and more forgiving but dulls sooner.
Is a harder knife always better?
No. Hardness and chip resistance pull in opposite directions. A harder blade holds its edge longer but is more brittle, so it is likelier to chip on bone, frozen food or a stone board. Above about 63 HRC a kitchen knife becomes noticeably less forgiving.
What hardness are Japanese-steel knives?
Our blades are forged from Japanese VG10 and AUS-10 steel and run at roughly 58 to 62 HRC. They are double bevel, ground at about 15 degrees per side, and are high-carbon stainless steel rather than plain carbon steel.
Does a higher HRC make a knife harder to sharpen?
It takes a little longer to raise a burr on harder steel, and it rewards a whetstone over a pull-through sharpener. In exchange you sharpen far less often, because the edge lasts longer.
Final Thoughts
If you have been shopping for some new kitchen knives then it’s likely that you’ll have seen something about the Rockwell hardness scale, and it is something that confuses a lot of people. In short, the scale tells us how well a material resists being indented; in the case of kitchen knives, that material is steel.
But harder doesn’t always mean better. If the steel is too hard it becomes more brittle and chips more easily, which is why makers aim for that sweet spot — and why the answer, for a Japanese-style kitchen blade, tends to land between 58 and 62 HRC. That is precisely where our own Japanese-steel knives sit, and we would rather print the number than ask you to take it on trust.
