Minimum Bend Radii: The minimum bend radius data shown in these charts is measured to the inside of the bend. The bend radii listed are standard minimum if manufacturing for aircraft and aerospace applications. Since commercial sheet metal bending can be done with less concern for stresses caused during forming operation, the radius can be near zero for thin sheet metal. Grain Direction is formed in metal in the direction in which the sheet was rolled at the steel mill. Grain Direction is not to be confused with surface finishes made by sanding or other finishing operations. Grain direction is often specified on stainless steel in order to achieve minimum bend radius or to control spring back. The grain can be seen by looking at a new piece of sheet metal and noticing the direction of visible lines going from one end to the other.

ALUMINUM - Recommended Minimum Bend Radius for maximum strength

 
THICKNESS OF ALUMINUM
MATERIAL .012 .016 .020 .025 .032 .040 .050 .063 .071 .080 .090 .100 .125 .160 .190
2024-0 & W .06 .06 .06 .06 .06 .06 .09 .09 .12 .12 .16 .19 .22 .31 .36
2024-T3 .06 .06 .06 .09 .09 .12 .16 .22 .25 .31 .38 .44 .62 .75 1.00
2024-T36 .06 .09 .09 .09 .12 .16 .19 .25 .31 .38 .44 .50 .75 1.00 1.25
3003-0 .06 .06 .06 .06 .06 .06 .06 .06 .09 .09 .09 .12 .12 .16 .19
3003-H14 .06 .06 .06 .06 .06 .09 .09 .12 .12 .16 .19 .22 .31 .38 .44
5052-0 .06 .06 .06 .06 .06 .06 .06 .09 .09 .09 .12 .12 .16 .19 .22
6061-0 & W .06 .06 .06 .06 .06 .06 .06 .09 .09 .09 ..12 .12 .16 .19 .22
6061-T4 & T6 .06 .06 .06 .06 .06 .06 .09 .09 .12 .12 .16 .19 .22 .31 .38
7075-0 & W .06 .06 .06 .06 .09 .09 .12 .16 .19 .22 .25 .31 .38 .50 .62
7075-T6 .06 .09 .12 .12 .16 .22 .25 .31 .41 .44 .50 .69 .87 1.00 1.25
7178-0 & W .06 .06 .06 .06 .09 .09 .12 .19 .22 .25 .31 .38 .50 .75
-
7178-T6 .06 .09 .16 .19 .22 .31 .38 .50 .56 .62 .62 .75 1.00 1.25
-

STAINLESS STEEL Recommended Minimum Bend Radius for maximum strength

 
THICKNESS OF STAINLESS STEEL
MATERIAL .012 .016 .020 .025 .032 .036 .040 .045 .050 .063 .080 .090 .112 .125 .160 .190
302 Annealed .06 .06 .06 .06 .06 .06 .09 .09 .09 .09 .12 .12 .16 .19 .22 .25
347-1A .06 .06 .06 .09 .09 .06 .06 .09 .09 .09 .12 .12 .16 .19 .22 .25
1/4 Hard Cres .06 .06 .06 .06 .06 .09 .09 .09 .12 .12 .16 .19 .22 .25 .31 .38
1/2 Hard Cres .06 .06 .06 .09 .09 .12 .12 .12 .16 .16 .25 .25 .31 .38 .50 .62
Full Hard Cres .06 .06 .09 .12 .12 .16 .16 .19 .22 .25 .31 .38 .44 .50 .62 .87

MILD STEEL Recommended Bend Allowance

BEND
RADIUS
THICKNESS OF MILD STEEL
0.022 0.032 0.040 0.051 0.064 0.091 0.128 0.187
Bend Allowance in inches per Degree
1/32
1/16
3/32
1/8		 0.00072
0.00126
0.00180
0.00235 		0.00079
0.00135
0.00188
0.00243 		0.00086
0.00140
0.00195
0.00249 		0.00094
0.00149
0.00203
0.00258 		0.00104
0.00159
0.00213
0.00268 		0.00125
0.00180
0.00234
0.00289 		0.00154
0.00209
0.00263
0.00317 		0.00200
0.00255
0.00309
0.00364
5/32
3/16
7/32
1/4 		0.00290
0.00344
0.00398
0.00454 		0.00297
0.00352
0.00406
0.00461 		0.00304
0.00358
0.00412
0.00467 		0.00312
0.00367
0.00421
0.00476 		0.00322
0.00377
0.00431
0.00486 		0.00343
0.00398
0.00452
0.00507 		0.00372
0.00426
0.00481
0.00535 		0.00418
0.00473
0.00527
0.00582
9/32
5/16
11/32
3/8 		0.00507
0.00562
0.00616
0.00671 		0.00515
0.00570
0.00624
0.00679 		0.00521
0.00576
0.00630
0.00685 		0.00530
0.00584
0.00639
0.00693 		0.00540
0.00595
0.00649
0.00704 		0.00561
0.00616
0.00670
0.00725 		0.00590
0.00644
0.00699
0.00753 		0.00636
0.00691
0.00745
0.00800
13/32
7/16
15/32
1/2 		0.00725
0.00780
0.00834
0.00889 		0.00733
0.00787
0.00842
0.00896 		0.00739
0.00794
0.00848
0.00903 		0.00748
0.00802
0.00857
0.00911 		0.00758
0.00812
0.00867
0.00921 		0.00779
0.00834
0.00888
0.00943 		0.00808
0.00862
0.00917
0.00971 		0.00854
0.00908
0.00963
0.01017
17/32
9/16
19/32
5/8 		0.00943
0.00998
0.01051
0.01107 		0.00951
0.01005
0.01058
0.01114 		0.00957
0.01012
0.01065
0.01121 		0.00966
0.01020
0.01073
0.01129 		0.00976
0.01030
0.01083
0.01139 		0.00997
0.01051
0.01105
0.01160 		0.01025
0.01080
0.01133
0.01189 		0.01072
0.01126
0.01179
0.01235
21/32
11/16
23/32
3/4 		0.01161
0.01216
0.01269
0.01324 		0.01170
0.01223
0.01276
0.01332 		0.01175
0.01230
0.01283
0.01338 		0.01183
0.01238
0.01291
0.01347 		0.01193
0.01248
0.01301
0.01357 		0.01214
0.01268
0.01322
0.01378 		0.01245
0.01298
0.01351
0.01407 		0.01289
0.01344
0.01397
0.01453

 

Below is a conversion chart that converts sheet metal gauge numbers into metal thickness.

26 gauge 24 ga. 22 ga. 20 ga . 18 ga. 16 ga. 14 ga. 13 ga. 12 ga. 11 ga. 10 ga. 9 ga. 8 ga. 7 ga. 6 ga.
.018" .024" .030" .036" .048" .060" .075" .090" .105" .120" .135" .150" .164" .180" .194
.46mm .61mm .76mm .91mm 1.2mm 1.5mm 1.9mm 2.3mm 2.7mm 3mm 3.4mm 3.8mm 4mm 4.6mm 4.9mm