# Hardness Conversion Calculator

Convert between Rockwell C (HRC), Rockwell B (HRB), Brinell (HB), Vickers (HV), and tensile strength. Approximate ASTM E140 values for steel.

## What this calculates

Convert between common hardness scales used in metallurgy and materials engineering. Enter a hardness value in one scale and get approximate equivalents in Rockwell C, Rockwell B, Brinell, Vickers, and tensile strength for steel.

## Inputs

- **Input Hardness Scale** — options: Rockwell C (HRC), Rockwell B (HRB), Brinell (HB), Vickers (HV) — Select which hardness scale you're converting from.
- **Hardness Value** — min 0 — Enter the hardness reading.

## Outputs

- **Rockwell C (HRC)** — Rockwell C hardness (hard steels, typically 20-70).
- **Rockwell B (HRB)** — Rockwell B hardness (softer steels, typically 60-100).
- **Brinell (HB)** — Brinell hardness number.
- **Vickers (HV)** — Vickers hardness number.
- **Approx. Tensile Strength** (ksi) — Approximate ultimate tensile strength in ksi (for steel).
- **Note** — formatted as text — Important caveats about this conversion.

## Details

Material hardness is measured with several different scales, and engineers often need to convert between them. Each scale uses a different test method (indenter shape, applied force), so conversions are approximate and depend on the material.

**Common Hardness Scales:**

| Scale | Method | Typical Use |
|-------|--------|-------------|
| Rockwell C (HRC) | Diamond cone, 150 kgf | Hardened steel (20-70 HRC) |
| Rockwell B (HRB) | 1/16" ball, 100 kgf | Softer steel, brass (60-100 HRB) |
| Brinell (HB) | 10mm ball, 3000 kgf | Castings, forgings |
| Vickers (HV) | Diamond pyramid | All materials, any hardness range |

**Example Conversions (Steel):**

| HRC | HB | HV | Tensile (ksi) |
|-----|-----|-----|---------------|
| 20 | 516 | 562 | 278 |
| 30 | 689 | 746 | 351 |
| 40 | 862 | 930 | 424 |
| 50 | 1035 | 1114 | 497 |
| 60 | 1208 | 1298 | 570 |

**Important:** These conversions are approximations based on ASTM E140 standard tables for carbon and alloy steels. Non-ferrous metals, stainless steels, and other alloys may have different conversion relationships. Always use material-specific data for critical applications.

## Frequently Asked Questions

**Q: Are hardness conversions exact?**

A: No. Hardness conversions between different scales are always approximate because each test uses a different indenter and force. The ASTM E140 standard provides conversion tables for specific material groups, but the exact relationship varies with material composition and heat treatment.

**Q: When should I use HRC vs HRB?**

A: Use Rockwell C (HRC) for hardened steels, typically above 20 HRC. Use Rockwell B (HRB) for softer metals like annealed steel, brass, and aluminum. The scales overlap slightly around the HRB 100 / HRC 20 region.

**Q: What is the relationship between hardness and tensile strength?**

A: For carbon and alloy steels, there's a roughly linear relationship between hardness and ultimate tensile strength. As a rule of thumb, tensile strength in psi is approximately Brinell hardness x 500. However, this relationship breaks down for very hard or very soft materials.

**Q: Can I convert hardness for non-steel materials?**

A: The conversion tables in this calculator are based on ASTM E140 data for carbon and alloy steels. Using them for aluminum, titanium, copper alloys, or plastics will give inaccurate results. For non-steel materials, look up material-specific conversion data.

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Source: https://vastcalc.com/calculators/conversion/hardness-conversion
Category: Conversion
Last updated: 2026-04-08