Drill Bit Size Chart

Drill sizes to 1" diameter

Legend

Fractional Inch

Letter Drill

Millimeters

Number Drill

Millimeters

Inches

Designation

Tap Drill/Pilot Drill Uses

.3429mm

.0135"

#80

.3683mm

.0145"

#79

.3969mm

.015625"

1/64"

#0 Pilot, Soft-Wood

.4064mm

.016"

#78

.4572mm

.018"

#77

.5mm

.0197"

.508mm

.02"

#76

.5334mm

.021"

#75

.5715mm

.0225"

#74

.6096mm

.024"

#73

.635mm

.025"

#72

.6604mm

.026"

#71

.7112mm

.028"

#70

.74168mm

.0292"

#69

.75mm

.0295"

M1x.25 coarse

.7874mm

.031"

#68

.7938mm

.03125"

1/32"

#0 Pilot, Hard-Wood #1 Pilot, Hard & Soft-Wood #2 Pilot, Soft-Wood

.8128mm

.032"

#67

.8382mm

.033"

#66

.85mm

.0335"

M1.1x.25 coarse

.889mm

.035"

#65

.9144mm

.036"

#64

.9398mm

.037"

#63

.95mm

.0374"

M1.2x.25 coarse

.9652mm

.038"

#62

.9906mm

.039"

#61

1mm

.0394"

1.016mm

.04"

#60

1.0414mm

.041"

#59

1.0668mm

.042"

#58

1.0922mm

.043"

#57

1.1mm

.0433"

M1.4x.3 coarse

1.1811mm

.0465"

#56

1.1906mm

.046875"

3/64"

#0-80 UNF#2 Pilot, Hard-wood, #3 Pilot, Soft-Wood #4 Pilot, Soft-Wood

1.25mm

.0492"

M1.6x.35 coarse

1.3mm

.0512"

M1.7x.35 coarse

1.3208mm

.052"

#55

1.397mm

.055"

#54

1.45mm

.0571"

M1.8x.35 coarse

1.5mm

.0591"

1.5113mm

.0595"

#53

#1-64 UNC, #1-72 UNF

1.5875mm

.0625"

1/16"

#0 Wood Shank Hole, #3 Pilot, Hard-Wood, #4 Pilot, Hard-wood #5 Pilot, Soft-wood, #6 Pilot, Soft-wood, #7 Pilot, Soft-wood

1.6mm

.063"

M2x.4 coarse

1.6129mm

.0635"

#52

1.7018mm

.067"

#51

1.75mm

.0689"

M2.2x.45 coarse

1.778mm

.07"

#50

#2-64 UNF, #2-56 UNC

1.8542mm

.073"

#49

1.9304mm

.076"

#48

1.9844mm

.078125"

5/64"

#1 Wood Shank Hole#5 Pilot, Hard-wood, #6 Pilot, Hard-wood #8 Pilot, Soft-wood, #9 Pilot, Soft-wood

1.9939mm

.0785"

#47

#3-48 UNC

2mm

.0787"

2.05mm

.0807"

M2.5x.45 coarse

2.0574mm

.081"

#46

2.0828mm

.082"

#45

#3-56 UNF

2.1844mm

.086"

#44

2.2606mm

.089"

#43

#4-40 UNC

2.3749mm

.0935"

#42

#4-48 UNF

2.3813mm

.09375"

3/32"

#2 Wood Shank Hole, #7 Pilot, Hard-wood, #8 Pilot, Hard-wood, #10 Pilot, Soft-wood, #11 Pilot, Soft-wood

2.4384mm

.096"

#41

2.4892mm

.098"

#40

2.5mm

.0984"

M3x.5 coarse

2.5273mm

.0995"

#39

2.5781mm

.1015"

#38

#5-40 UNC

2.6416mm

.104"

#37

#5-44 UNF

2.7051mm

.1065"

#36

#6-32 UNC

2.7781mm

.109375"

7/64"

#3 Wood Shank Hole, #4 Wood Shank Hole, #9 Pilot, Hard-wood #10 Pilot, Hard-wood, #12 Pilot, Soft-wood, #14 Pilot, Soft-wood

2.794mm

.11"

#35

2.8194mm

.111"

#34

2.8702mm

.113"

#33

#6-40 UNF

2.9mm

.1142"

M3.5x.6 coarse

2.9464mm

.116"

#32

3mm

.1181"

3.048mm

.12"

#31

3.175mm

.125"

1/8"

#5 Wood Shank Hole, #11 Pilot, Hard-wood, #12 Pilot, Hard-wood

3.2639mm

.1285"

#30

3.3mm

.1299"

M4x.7 coarse

3.4544mm

.136"

#29

#8-32 UNC, #8-36 UNF

3.5mm

.1378"

M4x.5 Fine

3.5687mm

.1405"

#28

3.5719mm

.140625"

9/64"

#6 Wood Shank Hole, #14 Pilot, Hard-wood, #16 Pilot, Soft-wood #18 Pilot, Soft-wood

3.6mm

.1417"

M4x.35 Fine

3.6576mm

.144"

#27

3.7mm

.1457"

M4.5x.75 coarse

3.7338mm

.147"

#26

3.7973mm

.1495"

#25

#10-24 UNC

3.8608mm

.152"

#24

3.9116mm

.154"

#23

3.9688mm

.15625"

5/32"

#7 Wood Shank Hole, #16 Pilot, Hard-wood

3.9878mm

.157"

#22

4mm

.1575"

4.0386mm

.159"

#21

#10-32 UNF

4.0894mm

.161"

#20

4.2mm

.1654"

M5x.8 coarse

4.2164mm

.166"

#19

4.3053mm

.1695"

#18

4.3656mm

.171875"

11/64"

#8 Wood Shank Hole, #20 Pilot, Soft-wood

4.3942mm

.173"

#17

#12-24 UNC

4.4958mm

.177"

#16

4.5mm

.1772"

M5x.5 Fine

4.572mm

.18"

#15

#12-28 UNF

4.6228mm

.182"

#14

4.699mm

.185"

#13

4.7625mm

.1875"

3/16"

#9 Wood Shank Hole, #10 Wood Shank Hole, #18 Pilot, Hardwood

4.8006mm

.189"

#12

4.8514mm

.191"

#11

4.9149mm

.1935"

#10

4.9784mm

.196"

# 9

5mm

.1969"

M6x1 coarse

5.0546mm

.199"

# 8

5.1054mm

.201"

# 7

1/4"-20 UNC

5.1594mm

.203125"

13/64"

#11 Wood Shank Hole, #20 Pilot, Hard-wood

5.1816mm

.204"

# 6

5.2197mm

.2055"

# 5

5.25mm

.2067"

M6x.75 Fine

5.3086mm

.209"

# 4

5.4102mm

.213"

# 3

1/4"-28 UNF

5.5mm

.2165"

M6x.5 Fine

5.5563mm

.21875"

7/32"

#12 Wood Shank Hole

5.6134mm

.221"

# 2

5.7912mm

.228"

# 1

5.9436mm

.234"

5.9531mm

.234375"

15/64"

6mm

.2362"

M7x1 coarse

6.0452mm

.238"

6.1468mm

.242"

6.2484mm

.246"

1/16"-27 NPT

6.25mm

.2461"

M7x.75 Fine

6.35mm

.25"

1/4"

#14 Wood Shank Hole

6.35mm

.25"

6.5mm

.2559"

6.5278mm

.257"

5/16"-18 UNC

6.6294mm

.261"

6.7469mm

.265625"

17/64"

#16 Wood Shank Hole

6.7564mm

.266"

6.8mm

.2677"

M8x1.25 coarse

6.9088mm

.272"

5/16"-24 UNF

7mm

.2756"

M8x.5 Fine

7.0358mm

.277"

7.1374mm

.281"

7.1438mm

.28125"

9/32"

7.25mm

.2854"

M8x.75 Fine

7.366mm

.29"

7.493mm

.295"

7.5mm

.2953"

M8x1 Fine

7.5406mm

.296875"

19/64"

#18 Wood Shank Hole

7.6708mm

.302"

7.8mm

.3071"

M9x1.25 coarse

7.9375mm

.3125"

5/16"

3/8"-16 UNC

8mm

.315"

M9x1 Fine

8.0264mm

.316"

8.2042mm

.323"

8.3344mm

.328125"

21/64"

#20 Wood Shank Hole

8.4328mm

.332"

3/8"-24 UNF

8.5mm

.3346"

M10x1.5 coarse

8.6106mm

.339"

1/8"-27 NPT

8.7313mm

.34375"

11/32"

8.8mm

.3465"

M10x1.25 Fine

8.8392mm

.348"

9mm

.3543"

M10x1 Fine

9.0932mm

.358"

7/16"-14 UNC

9.1281mm

.359375"

23/64"

9.25mm

.3642"

M10x.75 Fine

9.3472mm

.368"

9.5mm

.374"

M11x1.5 coarse

9.525mm

.375"

3/8"

9.5758mm

.377"

9.8044mm

.386"

9.9219mm

.390625"

25/64"

7/16"-20 UNF

10mm

.3937"

M11x1 Fine

10.0838mm

.397"

10.2mm

.4016"

M12x1.75 coarse

10.2616mm

.404"

10.3188mm

.40625"

13/32"

10.4902mm

.413"

10.5mm

.4134"

M12x1.5 Fine

10.7156mm

.421875"

27/64"

1/2"-13 UNC

11mm

.4331"

M12x1 Fine

11.1125mm

.4375"

7/16"

1/4"-18 NPT

11.25mm

.4429"

M12x.75 Fine

11.5mm

.4528"

11.5094mm

.453125"

29/64"

1/2"-20 UNF

11.9063mm

.46875"

15/32"

12mm

.4724"

M14x2 coarse

12.3031mm

.484375"

31/64"

9/16"-12 UNC

12.5mm

.4921"

M14x1.5 Fine

12.7mm

.5"

1/2"

12.8mm

.5039"

M14x1.25 Fine

13mm

.5118"

M14x1 Fine

13.0969mm

.515625"

33/64"

9/16"-18 UNF

13.4938mm

.53125"

17/32"

5/8"-11 UNC

13.5mm

.5315"

13.8906mm

.546875"

35/64"

14mm

.5512"

M16x2 coarse

14.2875mm

.5625"

9/16"

5/8"-18 UNF

14.5mm

.5709"

M16x1.5 Fine

14.6844mm

.578125"

37/64"

3/8"-18 NPT

15mm

.5906"

M16x1 Fine

15.0813mm

.59375"

19/32"

15.4781mm

.609375"

39/64"

15.5mm

.6102"

M18x2.5 coarse

15.875mm

.625"

5/8"

16mm

.6299"

M18x2 Fine

16.2719mm

.640625"

41/64"

3/4"-10 UNC

16.5mm

.6496"

16.6688mm

.65625"

21/32"

17mm

.6693"

M18x1 Fine

17.0656mm

.671875"

43/64"

17.4625mm

.6875"

11/16"

3/4"-16 UNF

17.5mm

.689"

M20x2.5 coarse

17.8594mm

.703125"

45/64"

1/2"-14 NPT

18mm

.7087"

M20x2 Fine

18.2563mm

.71875"

23/32"

18.5mm

.7283"

M20x1.5 Fine

18.6531mm

.734375"

47/64"

19mm

.748"

M20x1 Fine

19.05mm

.75"

3/4"

19.4469mm

.765625"

49/64"

7/8"-9 UNC

19.5mm

.7677"

M22x2.5 coarse

19.8438mm

.78125"

25/32"

20mm

.7874"

M22x2 Fine

20.2406mm

.796875"

51/64"

20.5mm

.8071"

M22x1.5 Fine

20.6375mm

.8125"

13/16"

7/8"-14 UNF

21mm

.8268"

M24x3 coarseM22x1 Fine

21.0344mm

.828125"

53/64"

21.4313mm

.84375"

27/32"

21.5mm

.8465"

21.8281mm

.859375"

55/64"

22mm

.8661"

M24x2 Fine

22.225mm

.875"

7/8"

1"-8 UNC

22.5mm

.8858"

M24x1.5 Fine

22.6219mm

.890625"

57/64"

23mm

.9055"

23.0188mm

.90625"

29/32"

1"-12 UNF

23.4156mm

.921875"

59/64"

3/4"-14 NPT

23.5mm

.9252"

23.8125mm

.9375"

15/16"

24mm

.9449"

M27x3 coarse

24.2094mm

.953125"

61/64"

24.5mm

.9646"

M26x1.5 Fine

24.6063mm

.96875"

31/32"

25mm

.9843"

M27x2 Fine

25.0031mm

.984375"

63/64"

1-1/8"-7 UNC

25.4mm

1.000"

When using a drill bit for a feeler gauge, please remember that many drill bits are actually undersize at the shank end of the drill bit so please use the above bit sizes with a grain of salt!

Also note that to correct for a broad feeler gauge or a loose-fitting drill bit:

ROC =^(D²-W²)/_8T

Where:

W = the width of the feeler gauge, or if the drill bit can be moved back and forth under the straight edge by the total amount W
D = mirror diameter,
T = gauge thickness or bit diameter.

Drill sizes to 1" diameter

ROC = (D2-W2)/8T

ROC =^(D²-W²)/_8T