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Hardness Conversion Calculator

Convert HRC, HRB, Vickers and Brinell steel hardness.

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How to use

  1. 1.Choose the hardness scale you already know: Rockwell C (HRC), Rockwell B (HRB), Vickers (HV) or Brinell (HB).
  2. 2.Type the hardness value you measured. The table range for that scale is shown beneath the field.
  3. 3.Read the equivalent values instantly — Rockwell, Vickers, Brinell and approximate tensile strength all update as you type.

About Hardness Conversion Calculator

This hardness conversion calculator turns one steel hardness value into all the others the instant you type it. Pick the scale you already know — Rockwell C (HRC), Rockwell B (HRB), Vickers (HV) or Brinell (HB) — enter the number, and it returns the equivalent value on every other scale plus an approximate ultimate tensile strength in MPa and ksi. There is no button to press and nothing is uploaded, so it is fast and private, and the answer updates as you type.

What the scales are: Rockwell C (HRC) is the workhorse for hardened steels, roughly HRC 20 to 68, read with a diamond cone under a 150 kgf load. Rockwell B (HRB) covers softer steels, up to about HRB 100, using a 1/16 inch ball under 100 kgf. Vickers (HV) presses a diamond pyramid and is defined across the whole range, which is why it makes the best backbone for a conversion table. Brinell (HB) presses a 10 mm ball under 3000 kgf and is quoted from about HB 100 to 650, with a tungsten-carbide ball (HBW) needed above roughly HB 650. Tensile strength is included because, for carbon and low-alloy steel, ultimate strength tracks hardness closely enough to give a useful estimate.

Why a lookup table and not a formula: the different tests measure different combinations of material behavior, so there is no exact, closed-form equation that converts one scale to another. Conversion is inherently empirical — the relationships come from measuring the same specimens on several machines and tabulating the results. This tool therefore stores discrete anchor rows from a published steel table and uses linear interpolation between them. Enter a value that lands exactly on an anchor and you get the standard number; land between anchors and it interpolates; go past the ends of a scale and it clearly says out of range rather than extrapolating a made-up figure. Because Rockwell C is undefined for very soft steel and Rockwell B saturates near 100, the table returns 'not defined' for a scale that does not apply at that hardness instead of inventing a value.

Where the numbers come from: the table follows the ASTM E140 and SAE J417 conversion data for non-austenitic carbon and low-alloy steels — the same widely reproduced chart used across engineering references (for example HRC 60 equals about HV 697, HB 654; HRC 40 equals HV 392, HB 371; HRC 20 equals HV 238, HB 222, HRB 97). Those anchors were cross-checked against two independent published reproductions before being built in.

Material limits matter: these conversions are approximate and are calibrated for carbon and low-alloy steel. Austenitic stainless steel, tool steel, hardened surfaces, cast iron and non-ferrous metals such as aluminum, copper and brass follow different relationships, so a converted number for those materials can be off by a wide margin — always test on the actual scale when it matters. Treat the tensile-strength figure as a rough guide, never a replacement for a real tensile test. To go further, try the Brinell hardness calculator to work out HB from an indentation, or the force and density converters for related material calculations.

Frequently asked questions

How do I convert Rockwell to Brinell hardness?
Select Rockwell C (HRC) as your input scale and enter the value; the Brinell (HB) equivalent appears instantly. For example, HRC 40 converts to about HB 371 and HRC 60 to about HB 654. The tool uses the ASTM E140 / SAE J417 steel table with linear interpolation between the standard anchor points, so values between listed hardnesses are estimated proportionally.
Why is hardness conversion only approximate?
Each hardness test measures a slightly different combination of material properties, so there is no exact formula linking the scales. Conversions come from empirically measuring the same specimens on several machines and tabulating the results. This calculator interpolates within that published table, which gives a close estimate for steel but never an exact, guaranteed value.
Does this work for stainless steel or aluminum?
No. The conversion table is calibrated for non-austenitic carbon and low-alloy steel. Austenitic stainless steel, tool steel, cast iron and non-ferrous metals such as aluminum, copper and brass follow different hardness relationships, so a converted value for those materials can be significantly off. Always measure on the actual scale when accuracy matters.
What is the difference between Rockwell C and Rockwell B?
Rockwell C (HRC) uses a diamond cone under a 150 kgf load and is used for hardened steel, roughly HRC 20 to 68. Rockwell B (HRB) uses a 1/16 inch steel ball under 100 kgf and is used for softer steel, up to about HRB 100. They barely overlap, so the tool returns 'not defined' when a value is too soft for HRC or too hard for HRB.
How accurate is the tensile strength estimate?
For carbon and low-alloy steel, ultimate tensile strength tracks hardness closely, so the MPa and ksi figures shown are a useful approximation drawn from the same ASTM E140-based table. It is only an estimate and applies to steel; treat it as a guide and never as a substitute for an actual tensile test, especially for critical or safety-related parts.

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