Surface pressure data

 
Surface pressure underneath head of hex cap screws DIN 931 / 933 (ISO 4014 / 4017) Hexagon Nuts DIN 934 (ISO 4032)
Nominal dimension Width across flats (mm) Washer face diameter (mm) Clearance hole (ISO 273) Bearing surface (mm) Stress area (mm2) Surface pressure underneath head N/mm2
8.8 10.9 12.9
M3 5.5 4.6 3.4 7.45 5.03 307 434 520
M4 7 5.9 4.5 11.4 8.78 352 496 596
M5 8 6.9 5.5 13.6 14.2 484 680 799
M6 10 8.9 6.6 28 20.1 332 466 559
M8 13 11.6 9 42 36.6 406 571 686
M10 16 14.6 11 72.3 58 375 528 633
M10 17 15.6 11 96.1 58 282 398 477
M12 18 16.6 13.5 73.2 84.3 541 760 913
M12 19 17.4 13.5 94.6 84.3 419 588 706
M14 21 19.6 15.5 113 115 481 676 812
M14 22 20.5 15.5 141 115 385 529 650
M16 24 22.5 17.5 157 157 476 669 803
M18 27 25.3 20 188 192 484 681 816
M20 30 28.2 22 244 245 480 672 807
M22 32 30 24 254 303 575 807 969
M22 34 31.7 24 337 303 433 608 730
M24 36 33.6 26 356 353 472 663 798
M27 41 38 30 427 459 518 728 876
M30 46 42.7 33 576 561 467 656 788
 
Surface pressure underneath head of socket hex cap screws DIN 912 (ISO 4762)
Nominal dimension Width across flats (mm) Washer face diameter (mm) Clearance hole (ISO 273) Bearing surface (mm) Stress area (mm) Surface  pressure underneath head N/mm2
8.8 10.9 12.9
M3 5.5 5.07 3.4 11.1 5.03 209 295 353
M4 7 6.35 4.5 17.6 8.78 228 322 386
M5 8.5 8.03 5.5 26.9 14.2 245 344 413
M6 10 9.38 6.6 34.9 20.1 266 374 449
M8 13 12.33 9 55.8 36.6 306 430 516
M10 16 15.33 11 89.5 58 303 427 512
M12 18 17.23 13.5 90 84.3 440 618 742
M14 21 20.17 15.5 131 115 415 583 700
M16 24 23.17 17.5 181 157 476 580 696
M18 27 25.87 20 211 192 431 607 727
M20 30 28.87 22 274 245 427 599 719
M22 33 31.81 24 342 303 427 599 719
M24 36 34.81 26 421 353 399 561 675
M27 40 38.61 30 464 459 476 670 608
M30 45 43.61 33 638 561 422 592 712
 

The values for surface pressure are obtained with 90% utilisation of the screw yield point.