Hardness Conversion Chart: HRC, HV, HB & Tensile Strength

A hardness conversion chart cross-references the different test standards (HRC, HV, HB, HRA, HRB, HRD), helping engineers grasp material strength and machinability. Converting between Rockwell (HRC), Vickers (HV) and Brinell (HB) judges machinability and estimates tensile strength — widely used in heat treatment, molds, cutting tools and machining, and key to material selection and quality control.

Hardness conversion HRC HV HB and tensile strength overview

1. What the Chart Is For

A hardness conversion chart is mainly used to convert between hardness standards, compare material strength and judge machinability — common in heat-treatment inspection, mold making and CNC machining.

Common hardness standards HRC HV HB

2. Common Hardness Standards

Standard	Material	Typical use
Rockwell HRC	Hard materials	Cutting tools, hardened steel
Vickers HV	Broad range, high accuracy	Thin parts, coatings, general
Brinell HB	Softer materials	Steel, castings

HRC HV HB hardness correspondence

3. HRC / HV / HB Correspondence (reference)

HRC	HV	HB standard ball	HB Hultgren ball	HB carbide ball	HRA
68	940	—	—	—	85.6
67	900	—	—	—	85.0
66	865	—	—	—	84.5
65	832	—	—	739	83.9
64	800	—	—	722	83.4
63	772	—	—	705	82.8
62	746	—	—	688	82.3
61	720	—	—	670	81.8
60	697	—	613	654	81.2
59	674	—	599	634	80.7
58	653	—	587	615	80.1
57	633	—	575	595	79.6
56	613	—	561	577	79.0
55	595	—	546	560	78.5
54	577	—	534	543	78.0
53	560	—	519	525	77.4
52	544	500	508	512	76.8
51	528	487	494	496	76.3
50	513	475	481	481	75.9
49	498	464	469	469	75.2
48	484	451	455	455	74.7
47	471	442	443	443	74.1
46	458	432	432	432	73.6
45	446	421	421	421	73.1
44	434	409	409	409	72.5
43	423	400	400	400	72.0
42	412	390	390	390	71.5
41	402	381	381	381	70.9
40	392	371	371	371	70.4
39	382	362	362	362	69.9
38	372	353	353	353	69.4
37	363	344	344	344	68.9
36	354	336	336	336	68.4
35	345	327	327	327	67.9
34	336	319	319	319	67.4
33	327	311	311	311	66.8
32	318	301	301	301	66.3
31	310	294	294	294	65.8
30	302	286	286	286	65.3
29	294	279	279	279	64.7
28	286	271	271	271	64.3
27	279	264	264	264	63.8
26	272	258	258	258	63.3
25	266	253	253	253	62.8
24	260	247	247	247	62.4
23	254	243	243	243	62.0
22	248	237	237	237	61.5
21	243	231	231	231	61.0
20	238	226	226	226	60.5
(18)	230	219	219	219	—
(16)	222	212	212	212	—
(14)	213	203	203	203	—
(12)	204	194	194	194	—
(10)	196	187	187	187	—
(8)	188	179	179	179	—
(6)	180	171	171	171	—
(4)	173	165	165	165	—
(2)	166	158	158	158	—
(0)	160	152	152	152	—

Higher HRC means a harder material; HV and HB cross-reference each other. The table above lists every step from HRC 68 down to (0); bracketed values are outside normal use. Its values come from ASTM E140 Table 3 (SAE-ASM-ASTM) and from approximations per the JIS Z 8413 and Z 8438 conversion tables, without marking which cell comes from which; where an authoritative value is needed, go to those standards. One HRC maps to three Brinell indenters (standard ball, Hultgren ball, carbide ball), so check which indenter was used before reading a value.

Heat treatment can leave the surface and core of the same part far apart in hardness. The table lists typical HRC ranges for common steels by heat-treatment state (bracketed values are outside the normal HRC range):

Material and heat treatment	HRC range
S45C, soft nitrided	62～57
SCM415, carburized and quenched	60～54
SCM440, induction hardened	57～49
S45C, induction hardened	53～47
SCM415, core	34～32
S45C, quenched and tempered	27～20
SCM440, core	27～20
S45C, core	(12)～(4)
SUS303	(10)～(0)

So on one S45C part, the soft-nitrided surface is HRC 57–62 while the core is only about (4)–(12), a gap of more than 50 HRC, and cutting conditions should change with depth; actual values still vary with case depth and tempering.

Rockwell HRA HRB HRD scales and tensile strength

4. Other Rockwell Scales

Scale	Load	Use
HRA	60 kgf	Super-hard materials (carbide)
HRB	100 kgf	Mild steel, copper
HRD	100 kgf	Medium-high hardness

The table below lists the other Rockwell scales and Shore hardness from the same source chart, step by step. Bracketed HRB values are outside normal use.

HRC	HRB	HRD	HS (Shore)
68	—	76.9	97
67	—	76.1	95
66	—	75.4	92
65	—	74.5	91
64	—	73.8	88
63	—	73.0	87
62	—	72.2	85
61	—	71.5	83
60	—	70.7	81
59	—	69.9	80
58	—	69.2	78
57	—	68.5	76
56	—	67.7	75
55	—	66.9	74
54	—	66.1	72
53	—	65.4	71
52	—	64.6	69
51	—	63.8	68
50	—	63.1	67
49	—	62.1	66
48	—	61.4	64
47	—	60.8	63
46	—	60.0	62
45	—	59.2	60
44	—	58.5	58
43	—	57.7	57
42	—	56.9	56
41	—	56.2	55
40	—	55.4	54
39	—	54.6	52
38	—	53.8	51
37	—	53.1	50
36	(109.0)	52.3	49
35	(108.5)	51.5	48
34	(108.0)	50.8	47
33	(107.5)	50.0	46
32	(107.0)	49.2	44
31	(106.0)	48.4	43
30	(105.5)	47.7	42
29	(104.5)	47.0	41
28	(104.0)	46.1	41
27	(103.0)	45.2	40
26	(102.5)	44.6	38
25	(101.5)	43.8	38
24	(101.0)	43.1	37
23	100.0	42.1	36
22	99.0	41.6	35
21	98.5	40.9	35
20	97.8	40.1	34
(18)	96.7	—	33
(16)	95.5	—	32
(14)	93.9	—	31
(12)	92.3	—	29
(10)	90.7	—	28
(8)	89.5	—	27
(6)	87.1	—	26
(4)	85.5	—	25
(2)	83.5	—	24
(0)	81.7	—	24

5. Hardness vs Tensile Strength (reference)

HRC	Tensile (kgf/mm²)	Tensile (N/mm² = MPa)
55	212	2079
54	205	2010
53	199	1952
52	192	1883
51	186	1824
50	179	1755
49	172	1687
48	167	1638
47	161	1579
46	156	1530
45	151	1481
44	146	1432
43	141	1383
42	136	1334
41	132	1294
40	127	1245
39	124	1216
38	120	1177
37	118	1157
36	114	1118
35	110	1079
34	108	1059
33	105	1030
32	102	1000
31	100	981
30	97	951
29	95	932
28	93	912
27	90	883
26	88	863
25	86	843
24	84	824
23	82	804
22	80	785
21	79	775
20	77	755
(18)	75	736
(16)	72	706
(14)	69	677
(12)	66	647
(10)	63	618
(8)	61	598
(6)	59	579
(4)	56	549
(2)	54	530
(0)	53	520

Tensile estimates for the same HRC differ between sources: according to Hitachi technical data, HV 500 (about HRC 49.1) corresponds to about 1750 MPa, while this table gives 1687 MPa at HRC 49. Both are approximations and must not be used for material acceptance — that takes an actual tensile test.

Tensile values are listed up to HRC 55 only. This only approximates carbon/alloy steels. For unit conversion (kgf/mm², MPa) see the SI Unit Conversion Guide.

6. Hardness and Machining

Higher hardness means higher cutting resistance. Rule: hard materials use a low feed with wear-resistant tools (carbide, coated); softer materials allow high-speed machining. Confirming hardness before machining helps set conditions and estimate tool life.

7. Notes on Use

Conversions are approximate; different materials vary with microstructure, heat treatment and test conditions. Formal specs should be measured directly with the named hardness standard, not taken from converted values.

FAQ

Q: Can HRC and HV be converted directly?

Approximately (e.g. HRC 60 ≈ HV 697), but it is an estimate. Because the principles differ (Rockwell measures depth, Vickers measures area), materials vary; for precision, measure directly with the named standard. See Hardness Testing Guide: Vickers, Rockwell & Knoop for details.

Q: Which of HRC, HV, HB should I use?

By hardness and part: hard (hardened steel, tools) use HRC; thin parts, coatings or high precision use HV; softer steel and castings use HB. Super-hard materials like carbide often use HRA.

Q: Can hardness estimate tensile strength?

For carbon/alloy steel it approximates (e.g. HRC 50 ≈ 179 kgf/mm² ≈ 1755 MPa), but it's only a reference. Stainless, cast iron and non-ferrous metals differ; critical designs should use an actual tensile test.

Q: Is higher hardness always better?

Not necessarily. Higher hardness is more wear-resistant and stronger, but toughness usually drops and it becomes brittle. Balance hardness and toughness by use, and note over-hard material needs low feed and wear-resistant tools, raising cost.

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Published: 2026-03-25 | Last updated: 2026-10-17