Hardness conversion lets you estimate the equivalent of a hardness value across different scales, for example from Vickers (HV) to Rockwell C (HRC), Brinell (HBW) or Rockwell B (HRB), and to approximate tensile strength. Use the interactive converter below, or the general reference tables. Conversions follow ISO 18265 and ASTM E140 and are material specific, so always pick the correct material family and, when a specification requires a scale, measure on that scale. For the wider context visit the Hardness Testing Academy.

Interactive hardness converter

Enter a value, choose its scale and the material family (steels, aluminium, brass or copper), and get the approximate equivalents on the other scales, including HV, HBW, HRC, HRB, HRA, the superficial Rockwell scales, Knoop and tensile strength.

Ferrous or non-ferrous: how the tables are organised

The real dividing line in hardness conversion is ferrous versus non-ferrous, not “hard” versus “soft”. Steels and cast irons, whether annealed, normalised, quenched and tempered or fully hardened, all lie on the same ferrous conversion curve. A single table therefore covers the whole range, from a soft annealed steel up to a hard quenched one (roughly HV 80 to HV 1000). What people call a “soft steel” is simply the low end of that same steel table, not a different material.

At the bottom of the steel range the diamond Rockwell C scale (HRC) is no longer applicable below about HRC 20, so the ball Rockwell B scale (HRB) takes over, exactly as it does on soft non-ferrous metals. You can see this where the steels table runs into the mild-steel region:

Non-ferrous metals are different. Brass, copper and aluminium are physically distinct, so at the same Vickers hardness they read 20 to 25 HRB points apart (at HV 80, copper is about 12 HRB, aluminium about 30 and brass about 37). They do not sit on a common curve and cannot be averaged into a single table without introducing errors, so each alloy family has its own dedicated table.

That is why this page shows one steels table that already includes mild steel at its lower end, and three separate non-ferrous tables for aluminium, brass and copper.

Steels and cast iron (approximate)

For common unalloyed and low-alloy steels and cast iron, in 5-point Rockwell C steps. For the full resolution and other scales, use the converter above.

Non-ferrous metals (approximate)

Non-ferrous metals follow their own conversion relationships, so each alloy family has a dedicated table, in 5-point Rockwell B steps. The Brinell load differs by family (aluminium and copper use HB5, brass uses HB10).

Aluminium alloys

Brass

Copper

Other material groups

Hardness conversion is material specific. For groups not listed above, ISO 18265 and ASTM E140 provide dedicated conversion tables; for exact values consult the standard or, better, measure directly on the required scale.

How accurate is a hardness conversion?

A conversion is an estimate, not a measurement. ISO 18265 and ASTM E140 give tables that are statistically valid for specific material families; the further the material drifts from the reference group, the larger the error. Learn how each scale is measured in the Rockwell, Brinell and Vickers guides.

When should you not convert hardness values?

Avoid conversion when a standard or drawing calls out a specific scale, and be especially careful with austenitic stainless steels, surface-hardened or coated parts and dissimilar materials. In these cases, measure directly on the required scale to avoid significant errors.

Frequently asked questions