Compare approximate Vickers, Brinell and Rockwell hardness values for the steel families covered by the selected standard. Enter one measured value to compare ISO 18265:2013 Table A.1 and ASTM E140−12b (2019) ε1 Table 1 side by side. Tensile strength estimates appear only in the ISO column.
Material matters: These steel tables do not establish a validated conversion for duplex, super duplex, austenitic stainless steel or nickel alloys. Converted values are estimates, not measured results or proof of material acceptance.
Steel Hardness Conversion Calculator
Enter one measured value in the left column. ISO and ASTM results appear side by side on the right, each calculated independently. Confirm that the material falls within the stated scope of the source tables.
Brinell inputs are separate: use the HB / HBS row for a confirmed steel-ball measurement and HBW for a tungsten-carbide-ball measurement. ISO Table A.1 lists steel-ball points from 76.0 to 447 HB and carbide-ball points from 456 to 618 HB. ASTM Table 1 lists 226–500 HBS and 226–739 HBW. No conversion is made across the ISO indenter change or outside these listed points. An unspecified “HB” on a certificate needs its indenter basis confirmed.
Note: Conversions are alloy-dependent per ASTM E140 / ISO 18265; actual values may vary by specific heat treatment and product form.
How to convert HV, HB and HRC
- Confirm the alloy family and material condition against the source table scope.
- Check the material against the table scopes below. The ISO and ASTM columns use separate datasets and evaluate the same original input independently.
- Enter one original hardness value in the left column. Read approximate ISO results in the middle column and ASTM results in the right column. For Brinell input, use the separate HB / HBS steel-ball row or HBW carbide-ball row; do not enter one as the other.
- Retain the original measured value and test scale when reporting a conversion. Use direct testing when required by the product specification or contract.
Between listed points, this calculator uses linear interpolation through the Vickers coordinate, with available endpoints checked for each output. This is the calculator's numerical method, not an additional ASTM conversion equation. It does not extrapolate. A blank result means the selected table provides no covered correspondence.
For ISO conversion used in test reporting, use the mean of at least three individual hardness values and record the original test method (ISO 18265:2013, Clause 3.1). The calculator accepts that mean as one input; it does not verify the underlying measurements.
Display precision follows the source column: ASTM Table 1 converted HRC is shown as an integer; other covered Rockwell outputs use one decimal place. Midpoint ties are rounded to the even retained digit. Original input values are retained without this output rounding. Numerical interpolation does not quantify material-dependent conversion uncertainty.
All conversions are approximate. Parentheses or an asterisk identify values outside the recommended or defined test-method range described by the source footnote; they are not statistical confidence intervals.
Source conversion tables: ISO and ASTM
These reference tables remain separate. The calculator above displays both result columns at once; no standard switch is needed. ISO uses HV10 and historical HB values. The Brinell columns are separated by indenter: HB / HBS (steel ball) and HBW (carbide ball). ISO values keep the original Table A.1 footnote basis; ASTM uses its separate HBS and HBW columns.
ISO 18265:2013 Table A.1 — view source values
| Rm (MPa) | HV | HB / HBS (steel ball) | HBW (carbide ball) | HRB | HRF | HRC | HRA | HRD | HR15N | HR30N | HR45N |
|---|
ASTM E140−12b (2019) ε1 Table 1 — view source values
| Rm (MPa) | HV | HB / HBS (steel ball) | HBW (carbide ball) | HRB | HRF | HRC | HRA | HRD | HR15N | HR30N | HR45N |
|---|
ISO Table A.1 footnote a: Brinell values up to 450 HB were obtained with a steel ball; higher values used a hardmetal ball. The calculator therefore assigns listed values up to 447 HB to the steel-ball row and listed values from 456 HB to the carbide-ball row. It does not interpolate across that change. Do not treat a low historical HB value as a directly measured modern HBW result.
Which materials do these conversion tables cover?
- ISO Table A.1: unalloyed and low-alloy steels and cast steel. Material condition still affects the relationship.
- ASTM Table 1: homogeneous non-austenitic carbon, alloy and tool steels in the stated forged, annealed, normalized, or quenched and tempered conditions, in the Rockwell C hardness range.
- Duplex and super duplex stainless steel: these tables alone do not validate conversions for 2205, 2507 or similar grades. Use direct measurement or a separately validated relationship for the relevant alloy and condition.
- Austenitic stainless steel: ASTM Table 5 concerns annealed plate and Table 6 concerns sheet, with limited scale combinations. Neither is a universal stainless steel conversion table.
- Nickel alloys: ASTM Table 3 has its own alloy and condition scope, including a nickel-content criterion above 50%. A trade name alone does not establish applicability. It is not implemented in this calculator.
Hardness conversion examples
For a material within ASTM Table 1 scope, 38 HRC corresponds approximately to 372 HV and 353 HBW. Report the measured 38 HRC with those converted estimates. The adjacent ISO column may show different values because its empirical dataset differs. Neither result is a universal conversion for all steels.
In ISO Table A.1, 295 HV10 corresponds to approximately 29.2 HRC; 300 HV10 corresponds to approximately 29.8 HRC. These examples describe the applicable steel table, not duplex stainless steel acceptance limits.
Frequently asked questions
Can I convert HRC to HV or Brinell hardness?
Yes, as an approximate comparison when the material and input fall within the selected table scope. The same conversion cannot be assumed valid for every alloy.
Can I use this converter for 2205 or 2507 duplex stainless steel?
This tool does not provide a validated duplex-specific conversion. For a specified hardness limit, test the required scale or use a relationship validated for that material and condition.
How accurate are hardness conversions?
There is no universal error percentage. Alloy composition, microstructure, heat treatment and the testing method affect the relationship. ASTM E140 §6 explains why a general confidence limit cannot be assigned.
Can hardness determine tensile strength?
The ISO column provides an approximate tensile strength estimate for its stated steel scope. ISO 18265 identifies tensile strength estimates as the least reliable conversions. They do not replace a tensile test or establish compliance with a minimum strength requirement. The ASTM column provides no tensile strength estimate and cannot convert a tensile strength input using Table 1.
Why does my mill certificate show a different value?
A directly measured value may differ from an estimate based on a conversion table. Confirm whether the certificate value was measured or converted, and check the standard edition, test scale, material condition and test details.
What happens outside the conversion range?
The affected column returns no conversion. The other column may still show an estimate if that same original input is covered by its table. The calculator does not substitute an endpoint, extrapolate or transfer a converted value from one standard to the other.
Are HB and HBW the same?
HB is a general or historical Brinell notation; HBS identifies a steel ball, while HBW identifies a tungsten carbide ball. This calculator separates the two indenter datasets. ISO Table A.1 footnote a assigns values up to 450 HB to steel-ball tests and higher values to hardmetal-ball tests. The actual listed points used here are 76.0–447 HB (steel ball) and 456–618 HB (carbide ball). HBW 90 has no correspondence in these selected table columns; HB / HBS 90 can be interpolated within the ISO steel-ball data. Confirm the indenter and test conditions if a certificate says only HB.
Sources and verification
Dataset review: 15 October 2026. Editions used: ISO 18265:2013, Table A.1 and footnotes (printed pages 13–16; Annex H, printed pages 80–83), Clauses 1–2; ASTM E140−12b (2019) ε1, Table 1 (printed page 3), §§1.1, 1.13, 5–7. This review identifies the editions used and does not certify that they are the latest editions.
Consult the licensed standards for full requirements: ISO 18265 and ASTM E140−12b (2019) ε1.
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