Hardness Conversion Calculator

Convert steel hardness between Brinell, Rockwell B, Rockwell C and Vickers.

Uses the standard steel table with lower-value lookup for in-between inputs.

Updated August 21, 2026

CreatorFrank Zhao

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Introduction / overview

The Hardness Conversion Calculator turns one hardness number into its equivalents on the other scales — Brinell (HB), Rockwell C (HRC), Rockwell B (HRB), and Vickers (HV). Pick the scale you have, type the number, and the other three fill in automatically. It also works the other way: edit any of the converted values and the original is re-derived from the same table.

Engineers, machinists, QC inspectors, and students use it when a drawing calls for one scale but the test report, supplier sheet, or shop instrument reports another. For example, a heat-treat note might specify $32\ \mathrm{HRC}$ while your hardness tester only reads Brinell.

There is no exact mathematical formula between these scales. The calculator uses the standard experimental steel conversion table — the same one found in handbooks — with a documented lower-value rule for numbers that fall between table rows.

How to use / quick start

1Choose the scale you want to enter under "I want to enter hardness in..." — HB, HRC, HRB, or HV. The matching input moves to the top so it is easy to spot.
2Type the hardness number. Stay inside the allowed range for that scale: HB 76–800, HRC 1–72, HRB 37–120, HV 80–746.
3Read the other three scales. They appear as derived (blue) values — these are the table equivalents, not additional inputs you need to fill.
4To convert the other direction, just change the selection and type a number on that scale. The calculator re-derives everything from the new entry.

Example — convert 300 HB

Select Brinell Hardness (HB) and type 300.

300\ \mathrm{HB}

\rightarrow

32\ \mathrm{HRC}

,\ \ 107\ \mathrm{HRB}

,\ \ 303\ \mathrm{HV}

The three derived fields turn blue and show 32 HRC, 107 HRB, and 303 HV — the same row from the steel table. If a scale has no equivalent for that hardness (for example, a very high HB with no HRB entry), that field stays blank instead of showing a misleading number.

Real-world examples

Supplier reports HB, drawing asks for HRC

A plate is certified at 250 HB. Does it meet a 25 HRC minimum?

Select Brinell Hardness (HB), type $250$ , and read HRC:

250\ \mathrm{HB}

\rightarrow

25\ \mathrm{HRC}

The equivalent is right on the limit. Because the conversion is approximate, treat this as a guide and confirm with an actual HRC test if the acceptance criterion is strict.

Hardness tester reads HRC, need Vickers for a report

Your Rockwell tester shows 60 HRC.

Switch the selector to Rockwell Scale 'C' (HRC), type $60$ :

60\ \mathrm{HRC}

\rightarrow

627\ \mathrm{HB}

,\ \ 746\ \mathrm{HV}

Note that there is no HRB equivalent at this hardness — the HRB field stays blank, which matches the table where very hard steels have no HRB entry.

Calculation method

This is an approximate conversion based on an experimental steel table, not a formula. The table lists matching values of $\mathrm{HB}$ , $\mathrm{HRC}$ , $\mathrm{HRB}$ , and $\mathrm{HV}$ measured on the same steel samples. Converting means looking up the row for your input and reading the other columns. Brinell hardness sits at the center of the network, so other scales convert through it.

Lookup rule

If your number falls exactly on a table entry, that row is used. If it falls between two entries, the nearest lower entry is used (the lower-value rule). Formally:

k = \max\{i \mid T_i \le x\},\quad y = S_k

$T_i$ are the values in the source column, $S_k$ is the value in the target column on the same row. When no equivalent exists for a hardness level (for example, very soft steels have no HRC entry), the result is left blank.

How the scales relate

\mathrm{HRC} = \mathrm{LUT}_{HB \to HRC}(\mathrm{HB})

,\quad

\mathrm{HRB} = \mathrm{LUT}_{HB \to HRB}(\mathrm{HB})

,\quad

\mathrm{HV} = \mathrm{LUT}_{HB \to HV}(\mathrm{HB})

$\mathrm{LUT}$ denotes the table lookup described above. Conversions from HRC, HRB, or HV first map back to HB and then to the requested target, so all paths stay consistent with the same underlying table.

Which way can it solve?

Any single hardness value drives the other three. Type a Vickers number and the tool derives Brinell and both Rockwell scales from the same lookup. There is no fixed input or output side.

Related concepts

What each scale actually measures

All four scales describe resistance to indentation, but they use different indenters and loads. Brinell (HB) presses a hard ball into the surface and relates load to the diameter of the impression — it is reported in $\mathrm{kgf/mm^2}$ . Vickers (HV) uses a diamond pyramid and the same pressure-like unit, which is why HB and HV track each other fairly closely. Rockwell B and C (HRB, HRC) measure the depth of indentation with a steel ball (B) or diamond cone (C) and report a dimensionless number. Because the test geometry differs, the scales line up only approximately.

Why Brinell is at the center

The underlying table is indexed most completely for Brinell. That is why the calculator converts other scales by mapping them to Brinell first and then to the target. Practically, this also means Brinell has the widest defined range in this tool (76–800), while HRC, HRB, and HV each cover the sub-range where that test is normally applied.

When a field stays blank

Very soft steels may have no HRC equivalent, and very hard steels may have no HRB equivalent — that is how the experimental table is structured, not a bug. If you enter $78\ \mathrm{HB}$ , HRC stays blank because 78 HB is below the HRC range in the table, while HRB and HV still show values. This is expected and matches handbook tables.

FAQs

Is the conversion exact?

No. Different scales use different loads and indenter shapes, and the table was built from measurements on steel. Treat the result as an approximate guide — useful for quoting, buying, or choosing a test method, but not a substitute for testing on the specified scale when a standard requires it.

What happens if my value falls between two table entries?

The calculator uses the nearest lower entry. For example, 269 HV falls between 262 HV and 271 HV in the table, so the 262 HV row is used. This is the conventional approach for handbook conversions and keeps the result on the conservative side.

Can I use this for materials other than steel?

The table was compiled for steel. Hardness relationships depend on composition and microstructure, so conversions for aluminum, copper alloys, plastics, or case-hardened layers can be significantly off. For non-steel materials, use a material-specific table or measure directly on the required scale.

Limitations

A few practical boundaries to keep in mind

Approximate and steel-specific
All conversions are approximate and derived from steel data. Do not use them as certified equivalents for other alloys or for formal compliance without a direct test.
Input must be inside the allowed range
Values outside HB 76–800, HRC 1–72, HRB 37–120, or HV 80–746 are flagged as out of range. Even inside the range, some hardness levels have no equivalent on another scale — the field then stays blank, which is expected.
Lower-value rule between rows
Numbers between table rows are mapped to the nearest lower row, not interpolated. If you need a finer estimate, consult a detailed handbook or interpolate manually with care.

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