Hardness Scale & Conversions

Reference Article

Common Hardness Scales

  • Brinell Hardness - Used for determining the hardness of metals. This hardness scale is often used for steel parts and comparative conversions between Brinell and Rockwell scales. The comparative scales are listed in the chart below.
  • Rockwell Hardness - Probably the most familiar hardness measurement technique because of its' wide range. Useful for measuring many materials from soft bearing metals to carbides. The different Rockwell scales are listed in the chart below.
  • Shore's Hardness - a common scale for elastic materials such as rubber and plastics.
  • Vicker's Hardness - useful for thin materials.
  • Knoop Hardness - a test applicable to thin materials, plated surfaces, exceptionally hard and brittle materials and shallow hardened surfaces such as surfaces nitrided or carburized.
Hardness Conversion Chart
Brinell Hardness
Rockwell Hardness
A Scale
B Scale
C Scale
--
85.6
--
68.0
--
85.3
--
67.5
--
85.0
--
67.0
767
84.7
--
66.4
757
84.4
--
65.9
745
84.1
--
65.3
733
83.8
--
64.7
722
83.4
--
64.0
712
--
--
--
710
83.0
--
63.3
698
82.6
--
62.5
684
82.2
--
61.8
682
82.2
--
61.7
670
81.8
--
61.0
656
81.3
--
60.1
653
81.2
--
60.0
647
81.1
--
59.7
638
80.8
--
59.2
630
80.6
--
58.8
627
80.5
--
58.7
601
79.8
--
57.3
578
79.1
--
56.0
555
78.4
--
54.7
534
77.8
--
53.5
514
76.9
--
52.1
495
76.3
--
51.0
477
75.6
--
49.6
461
74.9
--
48.5
444
74.2
--
47.1
429
73.4
--
45.7
415
72.8
--
44.5
401
72.0
--
43.1
388
71.4
--
41.8
375
70.6
--
40.4
363
70.0
--
39.1
352
69.3
--
37.9
341
68.7
--
36.6
 
Brinell Hardness 
Rockwell Hardness
A Scale
B Scale
C Scale
331
68.1
--
35.5
321
67.5
--
34.3
311
66.9
--
33.1
302
66.3
--
32.1
293
65.7
--
30.9
285
65.3
--
29.9
277
64.6
--
28.8
269
64.1
--
27.6
262
63.6
--
26.6
255
63.0
--
25.4
248
62.5
--
24.2
241
61.8
100.0
22.8
235
61.4
99.0
21.7
229
60.8
98.2
20.5
223
--
97.3
20.0
217
--
96.4
18.0
212
--
95.5
17.0
207
--
94.6
16.0
201
--
93.8
15.0
197
--
92.8
--
192
--
91.9
--
187
--
90.7
--
183
--
90.0
--
179
--
89.0
--
174
--
87.8
--
170
--
86.8
--
167
--
86.0
--
163
--
85.0
--
156
--
82.9
--
149
--
80.8
--
143
--
78.7
--
137
--
76.4
--
131
--
74.0
--
126
--
72.0
--
121
--
69.8
--
116
--
67.6
--
111
--
65.7
--
 
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