Hardness converter.

Hardness scales do not convert exactly: each test presses a different indenter with a different load. The ASTM A370 tables give agreed approximate equivalents for non-austenitic steels, for example HRC 30 ≈ 302 HV ≈ 286 HB ≈ 950 MPa tensile. Use them to compare, not to accept or reject parts.

Reviewed 11 Nov 2026 · Based on ASTM A370-17a Tables 2 and 3: approximate hardness conversion numbers for non-austenitic steels · Report an error

Questions on this?

302HV, approximate

Rockwell: 30.0 HRC
Brinell: 286 HB
Approx. tensile strength: 950 MPa

Approximate conversions for non-austenitic steels (ASTM A370 Tables 2 and 3). They depend on composition and heat treatment; do not use them for austenitic stainless (A2/A4) or for acceptance testing.

Rockwell C to other scales, non-austenitic steels
HRC	HV	HB (3000 kgf, 10 mm ball)	Approx. tensile (MPa)
68	940	–	–
67	900	–	–
66	865	–	–
65	832	739	–
64	800	722	–
63	772	706	–
62	746	688	–
61	720	670	–
60	697	654	–
59	674	634	2420
58	653	615	2330
57	633	595	2240
56	613	577	2160
55	595	560	2070
54	577	543	2010
53	560	525	1950
52	544	512	1880
51	528	496	1820
50	513	482	1760
49	498	468	1700
48	484	455	1640
47	471	442	1580
46	458	432	1520
45	446	421	1480
44	434	409	1430
43	423	400	1390
42	412	390	1340
41	402	381	1300
40	392	371	1250
39	382	362	1220
38	372	353	1180
37	363	344	1140
36	354	336	1110
35	345	327	1080
34	336	319	1050
33	327	311	1030
32	318	301	1010
31	310	294	970
30	302	286	950
29	294	279	930
28	286	271	900
27	279	264	880
26	272	258	860
25	266	253	850
24	260	247	820
23	254	243	810
22	248	237	790
21	243	231	770
20	238	226	760

Source: ASTM A370-17a, Table 2. – = no value in the table (no Brinell above HRC 65, no tensile strength above HRC 59).

Rockwell B to other scales, non-austenitic steels
HRB	HV	HB (3000 kgf, 10 mm ball)	Approx. tensile (MPa)
100	240	240	800
99	234	234	785
98	228	228	750
97	222	222	715
96	216	216	705
95	210	210	690
94	205	205	675
93	200	200	650
92	195	195	635
91	190	190	620
90	185	185	615
89	180	180	605
88	176	176	590
87	172	172	580
86	169	169	570
85	165	165	565
84	162	162	560
83	159	159	550
82	156	156	530
81	153	153	505
80	150	150	495
79	147	147	485
78	144	144	475
77	141	141	470
76	139	139	460
75	137	137	455
74	135	135	450
73	132	132	440
72	130	130	435
71	127	127	425
70	125	125	420
69	123	123	415
68	121	121	405
67	119	119	400
66	117	117	395
65	116	116	385
64	114	114	–
63	112	112	–
62	110	110	–
61	108	108	–
60	107	107	–
59	106	106	–
58	104	104	–
57	103	103	–
56	101	101	–
55	100	100	–

Source: ASTM A370-17a, Table 3. Below HRB 65 the table gives no tensile strength; below HRB 55 no Vickers or Brinell value, so this tool stops there.

Reference values, not a design.

Values are the nominal figures of the cited standards, or calculated from them where marked. The governing standard and your drawing always take precedence.

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Questions buyers ask.

How accurate is a hardness conversion?

Approximate only. ASTM A370 states that steels of different composition and processing deviate from the tabulated relationships, and that conversions should be used with caution for acceptance or rejection of product. Where a specification names a scale, test on that scale.

Can I convert hardness for stainless steel A2 or A4?

Not with these tables. They cover non-austenitic steels (carbon, alloy, ferritic and martensitic stainless). A2 and A4 are austenitic; ASTM A370 gives separate, more limited tables for them, which this tool does not use.

What hardness is a class 8.8 or 10.9 bolt?

ISO 898-1 sets the hardness ranges for each property class; use those values, not a conversion from tensile strength. This converter is for comparing a measured hardness on one scale with another.

Why is there no tensile strength above HRC 59?

The ASTM A370 table gives no tensile value above HRC 59, so the tool shows none. It does not extrapolate beyond the table in either direction.

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HRB	HV	HB (3000 kgf, 10 mm ball)	Approx. tensile (MPa)
100	240	240	800
99	234	234	785
98	228	228	750
97	222	222	715
96	216	216	705
95	210	210	690
94	205	205	675
93	200	200	650
92	195	195	635
91	190	190	620
90	185	185	615
89	180	180	605
88	176	176	590
87	172	172	580
86	169	169	570
85	165	165	565
84	162	162	560
83	159	159	550
82	156	156	530
81	153	153	505
80	150	150	495
79	147	147	485
78	144	144	475
77	141	141	470
76	139	139	460
75	137	137	455
74	135	135	450
73	132	132	440
72	130	130	435
71	127	127	425
70	125	125	420
69	123	123	415
68	121	121	405
67	119	119	400
66	117	117	395
65	116	116	385
64	114	114	–
63	112	112	–
62	110	110	–
61	108	108	–
60	107	107	–
59	106	106	–
58	104	104	–
57	103	103	–
56	101	101	–
55	100	100	–

HRB	HV	HB (3000 kgf, 10 mm ball)	Approx. tensile (MPa)
100	240	240	800
99	234	234	785
98	228	228	750
97	222	222	715
96	216	216	705
95	210	210	690
94	205	205	675
93	200	200	650
92	195	195	635
91	190	190	620
90	185	185	615
89	180	180	605
88	176	176	590
87	172	172	580
86	169	169	570
85	165	165	565
84	162	162	560
83	159	159	550
82	156	156	530
81	153	153	505
80	150	150	495
79	147	147	485
78	144	144	475
77	141	141	470
76	139	139	460
75	137	137	455
74	135	135	450
73	132	132	440
72	130	130	435
71	127	127	425
70	125	125	420
69	123	123	415
68	121	121	405
67	119	119	400
66	117	117	395
65	116	116	385
64	114	114	–
63	112	112	–
62	110	110	–
61	108	108	–
60	107	107	–
59	106	106	–
58	104	104	–
57	103	103	–
56	101	101	–
55	100	100	–

HRB	HV	HB (3000 kgf, 10 mm ball)	Approx. tensile (MPa)
100	240	240	800
99	234	234	785
98	228	228	750
97	222	222	715
96	216	216	705
95	210	210	690
94	205	205	675
93	200	200	650
92	195	195	635
91	190	190	620
90	185	185	615
89	180	180	605
88	176	176	590
87	172	172	580
86	169	169	570
85	165	165	565
84	162	162	560
83	159	159	550
82	156	156	530
81	153	153	505
80	150	150	495
79	147	147	485
78	144	144	475
77	141	141	470
76	139	139	460
75	137	137	455
74	135	135	450
73	132	132	440
72	130	130	435
71	127	127	425
70	125	125	420
69	123	123	415
68	121	121	405
67	119	119	400
66	117	117	395
65	116	116	385
64	114	114	–
63	112	112	–
62	110	110	–
61	108	108	–
60	107	107	–
59	106	106	–
58	104	104	–
57	103	103	–
56	101	101	–
55	100	100	–