Convert between metric and imperial units used in the steel trade, from tonnes and short tons to N/mm² and ksi, with approximate steel hardness conversions, wire gauges and nail sizes.
Type in either box. A comma works as a decimal point (2,5 = 2.5); with both a comma and a point, the comma is read as a thousands separator.
Approximate, for guidance only. These relationships hold for carbon and low-alloy (non-austenitic) steels in the annealed, normalised or quenched-and-tempered condition. They do not apply to austenitic stainless steel, cold-worked material or other metals. A hardness test does not replace a tensile test.
—Rockwell C (HRC)
—Rockwell B (HRB)
—Vickers (HV)
—Brinell (HB)
—Tensile strength, ksi (approx.)
—Tensile strength, MPa (approx.)
Values between table rows are interpolated. A dash means the tables do not cover that scale at this hardness.
Which gauge is this diameter?
The nearest gauge in each system. Wire is ordered by diameter in millimetres more often than by gauge now — say which gauge system you mean if you quote a number.
Length
Length
Common nail shank diameter
Common nail shank diameter
"Penny" (d) is the US trade size of a nail and fixes its length. The diameter is that of a bright common nail; box, finishing and roofing nails of the same size are thinner or have a different head.
Length — common conversions
From
Equals
1 in
25.4 mm
1 ft
0.3048 m
1 m
3.28084 ft
1 0.001 in
0.0254 mm
1 mi
1.60934 km
1 nmi
1.852 km
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is m.
Area — common conversions
From
Equals
1 in²
645.16 mm²
1 ft²
0.092903 m²
1 m²
10.7639 ft²
1 acre
4,046.86 m²
1 ha
2.47105 acre
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is m².
Volume — common conversions
From
Equals
1 m³
35.3147 ft³
1 US gallon
3.78541 L
1 imperial gallon
4.54609 L
1 42 US gal
158.987 L
1 yd³
0.764555 m³
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is m³.
Mass — common conversions
From
Equals
1 t
2,204.62 lb
1 lb
0.453592 kg
1 US
0.907185 t
1 UK
1.01605 t
1 t
1.10231 US
1 t
0.984207 UK
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is kg.
Density — common conversions
From
Equals
7.85 g/cm³
0.283599 lb/in³
7,850 kg/m³
490.059 lb/ft³
1 lb/in³
27.6799 g/cm³
490 lb/ft³
7,849.05 kg/m³
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is kg/m³.
Mass per length — common conversions
From
Equals
1 lb/ft
1.48816 kg/m
1 kg/m
0.671969 lb/ft
1 lb/yd
0.496055 kg/m
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is kg/m.
Mass per area — common conversions
From
Equals
0.9 oz/ft²
274.637 g/m²
275 g/m²
0.901191 oz/ft²
1 lb/ft²
4.88243 kg/m²
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is kg/m².
Force — common conversions
From
Equals
1 kgf
9.80665 N
1 tf
9.80665 kN
1 lbf
4.44822 N
1 1
4.44822 kN
1 US short
8.89644 kN
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is N.
Pressure & stress — common conversions
From
Equals
1 ksi
6.89476 MPa
355 MPa
51.4884 ksi
1 bar
14.5038 psi
1 kgf/mm²
9.80665 MPa
1 kgf/cm²
0.980665 bar
1 atm
101.325 kPa
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is Pa.
Torque — common conversions
From
Equals
1 lbf·ft
1.35582 N·m
1 kgf·m
9.80665 N·m
1 N·m
8.85075 lbf·in
100 N·m
73.7562 lbf·ft
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is N·m.
Energy — common conversions
From
Equals
1 kWh
3.6 MJ
1 BTU
1.05506 kJ
1 kcal
4.1868 kJ
1 kWh
3,412.14 BTU
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is J.
Power — common conversions
From
Equals
1 hp
0.7457 kW
1 kW
1.34102 hp
1 PS
0.735499 kW
1 TR
3.51685 kW
10,000 BTU/h
2.93071 kW
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is W.
Speed — common conversions
From
Equals
100 km/h
62.1371 mph
1 kn
1.852 km/h
1 m/s
196.85 ft/min
60 m/min
196.85 ft/min
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is m/s.
Flow rate — common conversions
From
Equals
1 m³/h
4.40287 gpm
1 L/s
3.6 m³/h
1 cfm
1.69901 m³/h
1,000 bbl/d
6.62447 m³/h
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is m³/s.
Frequency — common conversions
From
Equals
60 rpm
1 Hz
1,500 rpm
25 Hz
50 Hz
3,000 rpm
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is Hz.
Time — common conversions
From
Equals
1 d
24 h
1 week
168 h
1 365 days
365 d
8,760 h
365 d
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is s.
Second moment of area — common conversions
From
Equals
1 in⁴
41.6231 cm⁴
1 cm⁴
10,000 mm⁴
1,000 cm⁴
24.0251 in⁴
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is m⁴.
Section modulus — common conversions
From
Equals
1 in³
16.3871 cm³
100 cm³
6.10237 in³
Factors are exact definitions (NIST SP 811, the SI Brochure); the base unit is m³.
Temperature — common values
°C
°F
K
Note
-40
-40
233.15
0
32
273.15
water freezes
20
68
293.15
room temperature, test temperature
100
212
373.15
water boils
200
392
473.15
550
1,022
823.15
about the tempering range
723
1,333.4
996.15
A1, lower critical temperature of steel
912
1,673.6
1,185.15
A3 of pure iron
1538
2,800.4
1,811.15
iron melts
°F = °C × 9/5 + 32; K = °C + 273.15.
Hardness — approximate equivalents for steel
HRC
HV
HB
Tensile, ksi
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
351
2,420
58
653
615
338
2,330
57
633
595
325
2,241
56
613
577
313
2,158
55
595
560
301
2,075
54
577
543
292
2,013
53
560
525
283
1,951
52
544
512
273
1,882
51
528
496
264
1,820
50
513
481
255
1,758
49
498
469
246
1,696
48
484
455
238
1,641
47
471
443
229
1,579
46
458
432
221
1,524
45
446
421
215
1,482
44
434
409
208
1,434
43
423
400
201
1,386
42
412
390
194
1,338
41
402
381
188
1,296
40
392
371
182
1,255
39
382
362
177
1,220
38
372
353
171
1,179
37
363
344
166
1,145
36
354
336
161
1,110
35
345
327
156
1,076
34
336
319
152
1,048
33
327
311
149
1,027
32
318
301
146
1,007
31
310
294
141
972
30
302
286
138
951
29
294
279
135
931
28
286
271
131
903
27
279
264
128
883
26
272
258
125
862
25
266
253
123
848
24
260
247
119
820
23
254
243
117
807
22
248
237
115
793
21
243
231
112
772
20
238
226
110
758
Softer steels (Rockwell B range)
HB
HRB
Tensile, ksi
Tensile, MPa
241
100.0
116
800
235
99.0
114
786
229
98.2
111
765
223
97.3
104
717
217
96.4
103
710
212
95.5
100
689
207
94.6
99
683
201
93.8
97
669
197
92.8
94
648
192
91.9
92
634
187
90.7
90
621
183
90.0
89
614
179
89.0
88
607
174
87.8
86
593
170
86.8
84
579
167
86.0
83
572
163
85.0
82
565
156
82.9
80
552
149
80.8
73
503
143
78.7
71
490
137
76.4
67
462
131
74.0
65
448
126
72.0
63
434
121
69.0
60
414
116
67.6
58
400
111
65.7
56
386
Relationships as tabulated for non-austenitic steels in ASTM E140 and ASTM A370; Brinell with a 10 mm tungsten-carbide ball under 3,000 kgf. The commonly cited sour-service limit of 22 HRC is about 248 HV (see the steel calculators).
