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Socket & Wrench Size Chart

What size socket, wrench and hex key fits each metric and imperial bolt. ISO 4014 hex heads, ISO 4762 socket head cap screws, and SAE equivalents.

Hex-head sizes are across-flats. Modern ISO 4014/4017 hardware moved M10 to 16 mm and M12 to 18 mm; older DIN 931 parts still use 17 and 19 mm, which is why your set has both.

Metric coarse

BoltHex head (A/F)Older DINHex key (SHCS)
M1.6×0.35——1.5 mm
M2×0.4——1.5 mm
M2.5×0.45——2 mm
M3×0.55.5 mm—2.5 mm
M3.5×0.66 mm——
M4×0.77 mm—3 mm
M5×0.88 mm—4 mm
M6×110 mm—5 mm
M7×111 mm—6 mm
M8×1.2513 mm—6 mm
M10×1.516 mm17 mm8 mm
M12×1.7518 mm19 mm10 mm
M14×221 mm22 mm12 mm
M16×224 mm—14 mm
M18×2.527 mm—14 mm
M20×2.530 mm—17 mm
M22×2.534 mm32 mm17 mm
M24×336 mm—19 mm
M27×341 mm—19 mm
M30×3.546 mm—22 mm
M33×3.550 mm—24 mm
M36×455 mm—27 mm
M39×460 mm—27 mm
M42×4.565 mm—32 mm
M45×4.570 mm—32 mm
M48×575 mm—36 mm
M52×580 mm—36 mm
M56×5.585 mm—41 mm
M60×5.590 mm—41 mm
M64×695 mm—46 mm

Unified coarse (UNC)

BoltHex head (A/F) Hex key (SHCS)
#1-64 UNC5/32"—1/16
#2-56 UNC3/16"—5/64
#3-48 UNC3/16"—5/64
#4-40 UNC1/4"—3/32
#5-40 UNC5/16"—3/32
#6-32 UNC5/16"—7/64
#8-32 UNC11/32"—9/64
#10-24 UNC3/8"—5/32
#12-24 UNC7/16"—5/32
1/4-20 UNC7/16"—3/16
5/16-18 UNC1/2"—1/4
3/8-16 UNC9/16"—5/16
7/16-14 UNC5/8"—3/8
1/2-13 UNC3/4"—3/8
9/16-12 UNC13/16"—7/16
5/8-11 UNC15/16"—1/2
3/4-10 UNC1-1/8"—5/8
7/8-9 UNC1-5/16"—3/4
1-8 UNC1-1/2"—3/4
1-1/8-7 UNC1-11/16"—7/8
1-1/4-7 UNC1-7/8"—7/8
1-3/8-6 UNC2-1/16"—1
1-1/2-6 UNC2-1/4"—1