BIZOMAT MAKEOS · Materials
Vickers and Knoop Hardness from Indentation
What Vickers or Knoop hardness does this indentation give?
Vickers (HV) or Knoop (HK) hardness from the test force and the measured indentation diagonal, with the indentation depth for checking specimen or case thickness.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Test | choice | Indenter type. |
| Test force | kgf | Test force in kilograms-force (HV10 = 10 kgf; 1 kgf = 9.80665 N). |
| Mean diagonal (Vickers) or long diagonal (Knoop) | mm | Measured diagonal: mean of both diagonals for Vickers, long diagonal for Knoop. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Test
- What it is
- Which diamond indenter made the impression: the square-based Vickers pyramid or the elongated Knoop pyramid. Each uses a different formula and depth ratio.
- Units and format
- Choose one of 2 options from the list: Vickers (square pyramid, 136°); Knoop (elongated pyramid).
- Example
- The form opens with “Vickers (square pyramid, 136°)” selected as a worked example. Choose the option that matches your case.
What this means: Test force
- What it is
- The load applied to the indenter during the test, as set on the hardness tester. The number in a hardness scale name such as HV10 is this load.
- Units and format
- Enter a number in kgf: kgf. The form accepts 0.000001 kgf to 200 kgf. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 kgf as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- For a given diagonal, hardness rises in direct proportion to the force.
- Get it right
- Enter kilograms-force, not newtons: 1 kgf = 9.80665 N. A tester set in newtons must be converted.
What this means: Mean diagonal (Vickers) or long diagonal (Knoop)
- What it is
- The length of the indentation diagonal measured under the microscope. For Vickers it is the average of the two diagonals; for Knoop it is the long diagonal only.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.3 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Hardness falls with the square of the diagonal, so measuring accurately matters.
- Get it right
- Enter millimetres; microscope readings are often in micrometres, so divide by 1000.
Method and formulas
- Vickers: HV = 1.8544 F ÷ d²; depth ≈ d ÷ 7.
- Knoop: HK = 14.229 F ÷ L²; depth ≈ L ÷ 30.
- Minimum thickness ≈ 1.5 × diagonal (Vickers) or 10 × depth (Knoop).
- Example: HV10 with a 0.3 mm diagonal is 206.04 HV.
Limitations
- Diagonals must be measured accurately; small indentations magnify measurement error.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Calculate hardness from a microhardness reading
- Check case depth traverses
- Check minimum specimen thickness
Who it is for
- Quality inspectors
- Metallurgists
- Materials engineers
What you get
- Hardness number
- Indentation depth
- Minimum specimen thickness
Interpreting the result
- Report the force with the result (e.g. 206 HV10).
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1406–1412. Topic reference; no source tables or recommended settings are reproduced.
- ISO 6507-1 Vickers hardness test; ISO 4545-1 Knoop hardness test
Learn the Concepts Behind This Tool
These BIZOMAT Library readings explain the method this tool uses, with worked examples.
Method explained here · BIZOMAT original book
Why induction hardening
In Induction Hardening by the Numbers
What it covers: What induction hardening does and why it is used: a hard, wear-resistant case on a tough core, heat made inside the part by eddy currents, the steps of the process and the numbers that control it.
Method explained here · BIZOMAT original book
Hardness traverses and microhardness
In Microstructures by the Numbers
What it covers: Measuring a hardened case with a microhardness traverse, keeping indentations valid, finding the effective hardened depth, and how diagonal measurement uncertainty limits the result.
Method explained here · BIZOMAT original book
Testing a nitrided layer
In Plasma Surface Engineering by the Numbers
What it covers: How to prove a nitrided layer with coupons, metallography and a microhardness traverse, how to read nitriding depth, and why a Rockwell C test on a nitrided surface misleads.
BIZOMAT tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Vickers and Knoop Hardness from Indentation calculator