GBP 57 Width across flats of screws and nuts Standard range With small hexagon With large hexagon Wood screws DIN EN ISO DIN EN ISO DIN DIN 561 DIN 564 DIN EN 14399 DIN 571 4016 4018 609 4014 4017 610 8765 8676 7968 DIN EN ISO DIN DIN DIN EN 14399 24036 917 935 4034 1587 4032 986 10513 10512 10511 Threads mm Threads mm Threads mm ⌀ mm M 1.6 3.2 M2 4 M 2.5 5 M3 5.5 M4 7 4 7 M5 8 5 8 M6 10 M6 8 6 10 M8 13 M8 10 8 13 M 10 16 (17) M 10 13 10 17 M 12 18 (19) M 12 17 M 12 22 12 19 M 14 21 (22) M 16 24 M 16 19 M 16 27 16 24 M 18 27 M 20 30 M 20 24 M 20 32 20 30 M 22 34 (32) M 22 36 M 24 36 M 24 30 M 24 41 M 27 41 M 27 46 M 30 46 M 30 36 M 30 50 M 33 50 M 36 55 M 36 46 M 36 60 M 39 60 M 42 65 M 42 55 M 45 70 M 48 75 M 48 65 M 52 80 Tolerances for width across flats Extract from DIN ISO 691. S S S Width across flats in mm Width across flats in mm Width across flats in mm S S S Nominal dimension minimum maximum Nominal dimension minimum maximum Nominal dimension minimum maximum 3.2* 3.22 3.28 17* 17.05 17.30 46* 46.10 46.60 3.5 3.52 3.60 18* 18.05 18.30 50* 50.10 50.60 4* 4.02 4.12 19* 19.06 19.36 55* 55.12 55.72 4.5 4.52 4.62 20* 20.06 20.36 60* 60.12 60.72 5* 5.02 5.12 21* 21.06 21.36 65* 65.12 65.72 5.5* 5.52 5.62 22* 22.06 22.36 70* 70.12 70.72 6* 6.03 6.15 23* 23.06 23.36 75* 75.15 75.85 7* 7.03 7.15 24* 24.06 24.36 80* 80.15 80.85 8* 8.03 8.15 25* 25.06 25.36 85* 85.15 85.85 9* 9.03 9.15 26* 26.08 26.48 90* 90.15 90.85 10* 10.04 10.19 27* 27.08 27.48 95* 95.15 95.85 11* 11.04 11.19 28* 28.08 28.48 100* 100.15 100.85 12* 12.04 12.24 30* 30.08 30.48 105* 105.20 106.00 13* 13.04 13.24 32* 32.08 32.48 110* 110.20 111.00 14* 14.05 14.27 34* 34.10 34.60 115* 115.20 116.00 i 15* 16* 15.05 16.05 15.27 16.27 The widths marked * comply with International Standards. 36* 41* 36.10 41.10 36.60 41.60 120* 120.20 121.00 1230