Vickers Hardness Number Calculator

About the Vickers Hardness Number Calculator

The Vickers Hardness Number Calculator computes HV hardness from the applied force and measured diagonal of the diamond pyramid indent. The Vickers test is the most versatile hardness testing method — a single continuous scale covers everything from soft lead (HV 5) to sapphire and tungsten carbide (HV 2200+), making it the universal reference for material hardness.

In a Vickers test, a square-based diamond pyramid with a 136° face angle is pressed into the surface under a controlled force. After the load is removed, the two diagonals of the resulting square impression are measured under a microscope and averaged. The calculator applies the standard formula HV = 1.8544 × F / d², where F is in kgf and d is the average diagonal in mm. It also provides approximate conversions to Brinell (HB), Rockwell C (HRC), and ultimate tensile strength (UTS) for steels.

Whether you\'re working in a metallurgy lab, conducting quality control on heat-treated parts, performing microhardness testing on thin coatings, or studying material science, this calculator delivers hardness results with cross-scale conversions and material identification.

When This Page Helps

The Vickers test is the gold standard for hardness measurement because it covers the entire hardness spectrum on one continuous scale. This calculator eliminates working by hand from measured diagonals, provides cross-scale conversions, and identifies the closest matching material. The optional two-diagonal input handles anisotropic indentations, and the reverse mode predicts what diagonal to expect for a given material.

For quality control labs processing dozens of tests daily, This calculator saves time and reduces calculation errors.

How to Use the Inputs

1. Select calculation mode: HV from diagonal or diagonal from known HV.
2. Enter the applied test force and select units (kgf, gf, or N).
3. Enter the average diagonal measurement in mm (or enter both diagonals separately).
4. Use preset buttons for common material hardness values.
5. Review the HV result along with approximate Brinell, Rockwell, and tensile strength.
6. Check the hardness scale gauge for visual context.
7. Consult the material reference table to identify your sample.

Example Calculation

Tips & Best Practices

• Always measure both diagonals and use their average — asymmetric indents indicate testing problems.
• Ensure the specimen surface is polished to at least 600-grit for clear diagonal measurement.
• The indent should be at least 2.5 diagonals from any edge or previous indent.
• For microhardness, vibration isolation and precise positioning are critical.
• Report results with the force designation: e.g., "720 HV 30" means 720 HV at 30 kgf.
• If diagonals differ by more than 5%, reject the measurement and re-test.

The Vickers Diamond Pyramid

The Vickers indenter is a right pyramid with a square base and a 136° angle between opposite faces. This geometry produces geometrically similar impressions at all forces, meaning hardness values are (ideally) independent of test force — a major advantage over Brinell testing where ball deformation introduces force-dependent errors at high hardness. The diamond material (approximately 10,000 HV) allows testing of the hardest engineering materials.

Microhardness and Materials Science

Microhardness Vickers testing (HV 0.01 to HV 0.5) enables measurements on individual metallographic features: grains, phases, inclusions, and thin coatings. A typical microhardness setup includes a metallurgical microscope with a built-in indenter and precision force mechanism. Indentations are measured at 400× magnification. This technique is essential for weld characterization (mapping hardness across the HAZ), surface treatment evaluation, and failure analysis.

Industrial Quality Control

In production environments, Vickers testing validates heat treatment outcomes (case hardening, through-hardening, nitriding), verifies incoming material properties, and monitors process consistency. Modern automated Vickers testers can perform hundreds of indentations per hour with computerized diagonal measurement, generating hardness maps across entire cross-sections. The ISO 6507 standard governs macro, low-force, and microhardness Vickers testing procedures worldwide.

Frequently Asked Questions

• Why does the Vickers test use a 136° diamond pyramid?

  The 136° angle was chosen so that the resulting HV numbers closely match Brinell hardness numbers in the overlapping range (HV/HB ≈ 1.05 for steel). It also produces well-defined, measurable impressions.

• What is the difference between macro, low-force, and micro Vickers?

  Macro Vickers uses forces of 1–120 kgf (HV 1 to HV 120). Low-force Vickers uses 0.2–1 kgf. Microhardness (HV 0.01 to HV 0.2) uses forces below 200 gf for thin films, coatings, and individual grains.

• How accurate are Vickers to Rockwell conversions?

  For carbon and alloy steels in the HV 200–900 range, conversions are within ±1–2 HRC points per ASTM E140. For non-ferrous metals or extreme hardness, conversions are less reliable.

• Can I test thin coatings with Vickers?

  Yes — microhardness Vickers (forces < 200 gf) produces very small indents suitable for thin coatings, plating, and individual metallographic phases. The indent depth should be less than 1/10 the coating thickness.

• Why do my two diagonal measurements differ?

  Anisotropy (directional hardness), surface tilt, vibration, or residual stress can cause unequal diagonals. The standard procedure averages d₁ and d₂. If they differ by more than 5%, the test may be invalid.

• How does Vickers compare to Knoop hardness?

  Both use diamond indenters under similar forces. Knoop produces an elongated impression (7:1 ratio) ideal for very thin or brittle specimens. Vickers produces a square impression and is more universally used.