Drill Size Chart: Number, Letter and Fraction Drills, Decimal and mm

Drill sizes · smallest to largest · 234 drills
Drill	Inches	mm	Common use
#80number	0.0135	0.343
#79number	0.0145	0.368
1/64fraction	0.0156	0.397
#78number	0.0160	0.406
#77number	0.0180	0.457
#76number	0.0200	0.508
#75number	0.0210	0.533
#74number	0.0225	0.571
#73number	0.0240	0.610
#72number	0.0250	0.635
#71number	0.0260	0.660
#70number	0.0280	0.711
#69number	0.0292	0.742
#68number	0.0310	0.787
1/32fraction	0.0313	0.794
#67number	0.0320	0.813
#66number	0.0330	0.838
#65number	0.0350	0.889
#64number	0.0360	0.914
#63number	0.0370	0.940
#62number	0.0380	0.965
#61number	0.0390	0.991
#60number	0.0400	1.016
#59number	0.0410	1.041
#58number	0.0420	1.067
#57number	0.0430	1.092
#56number	0.0465	1.181
3/64fraction	0.0469	1.191	Tap drill for #0-80 UNF
#55number	0.0520	1.321
#54number	0.0550	1.397
#53number	0.0595	1.511	Tap drill for #1-64 UNC, #1-72 UNF
1/16fraction	0.0625	1.587
#52number	0.0635	1.613	Close fit for #0 screws
#51number	0.0670	1.702
#50number	0.0700	1.778	Tap drill for #2-56 UNC, #2-64 UNF; free fit for #0 screws
#49number	0.0730	1.854
#48number	0.0760	1.930	Close fit for #1 screws
5/64fraction	0.0781	1.984
#47number	0.0785	1.994	Tap drill for #3-48 UNC
#46number	0.0810	2.057	Free fit for #1 screws
#45number	0.0820	2.083	Tap drill for #3-56 UNF
#44number	0.0860	2.184
#43number	0.0890	2.261	Tap drill for #4-40 UNC; close fit for #2 screws
#42number	0.0935	2.375	Tap drill for #4-48 UNF
3/32fraction	0.0938	2.381
#41number	0.0960	2.438	Free fit for #2 screws
#40number	0.0980	2.489
#39number	0.0995	2.527
#38number	0.1015	2.578	Tap drill for #5-40 UNC
#37number	0.1040	2.642	Tap drill for #5-44 UNF; close fit for #3 screws
#36number	0.1065	2.705	Tap drill for #6-32 UNC
7/64fraction	0.1094	2.778
#35number	0.1100	2.794	Free fit for #3 screws
#34number	0.1110	2.819
#33number	0.1130	2.870	Tap drill for #6-40 UNF
#32number	0.1160	2.946	Close fit for #4 screws
#31number	0.1200	3.048
1/8fraction	0.1250	3.175
#30number	0.1285	3.264	Close fit for #5 screws; free fit for #4 screws
#29number	0.1360	3.454	Tap drill for #8-32 UNC, #8-36 UNF; free fit for #5 screws
#28number	0.1405	3.569
9/64fraction	0.1406	3.572
#27number	0.1440	3.658	Close fit for #6 screws
#26number	0.1470	3.734
#25number	0.1495	3.797	Tap drill for #10-24 UNC; free fit for #6 screws
#24number	0.1520	3.861
#23number	0.1540	3.912
5/32fraction	0.1563	3.969
#22number	0.1570	3.988
#21number	0.1590	4.039	Tap drill for #10-32 UNF
#20number	0.1610	4.089
#19number	0.1660	4.216
#18number	0.1695	4.305	Close fit for #8 screws
11/64fraction	0.1719	4.366
#17number	0.1730	4.394
#16number	0.1770	4.496	Tap drill for #12-24 UNC; free fit for #8 screws
#15number	0.1800	4.572
#14number	0.1820	4.623	Tap drill for #12-28 UNF
#13number	0.1850	4.699
3/16fraction	0.1875	4.762
#12number	0.1890	4.801
#11number	0.1910	4.851
#10number	0.1935	4.915
#9number	0.1960	4.978	Close fit for #10 screws
#8number	0.1990	5.055
#7number	0.2010	5.105	Tap drill for 1/4-20 UNC; free fit for #10 screws
13/64fraction	0.2031	5.159
#6number	0.2040	5.182
#5number	0.2055	5.220
#4number	0.2090	5.309
#3number	0.2130	5.410	Tap drill for 1/4-28 UNF
7/32fraction	0.2188	5.556
#2number	0.2210	5.613	Close fit for #12 screws
#1number	0.2280	5.791	Free fit for #12 screws
Aletter	0.2340	5.944
15/64fraction	0.2344	5.953
Bletter	0.2380	6.045
Cletter	0.2420	6.147
Dletter	0.2460	6.248
1/4fraction	0.2500	6.350
Eletter	0.2500	6.350
Fletter	0.2570	6.528	Tap drill for 5/16-18 UNC; close fit for 1/4 screws
Gletter	0.2610	6.629
17/64fraction	0.2656	6.747
Hletter	0.2660	6.756	Free fit for 1/4 screws
Iletter	0.2720	6.909	Tap drill for 5/16-24 UNF
Jletter	0.2770	7.036
Kletter	0.2810	7.137
9/32fraction	0.2813	7.144
Lletter	0.2900	7.366
Mletter	0.2950	7.493
19/64fraction	0.2969	7.541
Nletter	0.3020	7.671
5/16fraction	0.3125	7.938	Tap drill for 3/8-16 UNC
Oletter	0.3160	8.026
Pletter	0.3230	8.204	Close fit for 5/16 screws
21/64fraction	0.3281	8.334
Qletter	0.3320	8.433	Tap drill for 3/8-24 UNF; free fit for 5/16 screws
Rletter	0.3390	8.611
11/32fraction	0.3438	8.731
Sletter	0.3480	8.839
Tletter	0.3580	9.093
23/64fraction	0.3594	9.128
Uletter	0.3680	9.347	Tap drill for 7/16-14 UNC
3/8fraction	0.3750	9.525
Vletter	0.3770	9.576
Wletter	0.3860	9.804	Close fit for 3/8 screws
25/64fraction	0.3906	9.922	Tap drill for 7/16-20 UNF
Xletter	0.3970	10.084	Free fit for 3/8 screws
Yletter	0.4040	10.262
13/32fraction	0.4063	10.319
Zletter	0.4130	10.490
27/64fraction	0.4219	10.716	Tap drill for 1/2-13 UNC
7/16fraction	0.4375	11.112
29/64fraction	0.4531	11.509	Tap drill for 1/2-20 UNF; close fit for 7/16 screws
15/32fraction	0.4688	11.906	Free fit for 7/16 screws
31/64fraction	0.4844	12.303	Tap drill for 9/16-12 UNC
1/2fraction	0.5000	12.700
33/64fraction	0.5156	13.097	Tap drill for 9/16-18 UNF; close fit for 1/2 screws
17/32fraction	0.5313	13.494	Tap drill for 5/8-11 UNC; free fit for 1/2 screws
35/64fraction	0.5469	13.891
9/16fraction	0.5625	14.287
37/64fraction	0.5781	14.684	Tap drill for 5/8-18 UNF; close fit for 9/16 screws
19/32fraction	0.5938	15.081	Free fit for 9/16 screws
39/64fraction	0.6094	15.478
5/8fraction	0.6250	15.875
41/64fraction	0.6406	16.272	Close fit for 5/8 screws
21/32fraction	0.6563	16.669	Tap drill for 3/4-10 UNC; free fit for 5/8 screws
43/64fraction	0.6719	17.066
11/16fraction	0.6875	17.462	Tap drill for 3/4-16 UNF
45/64fraction	0.7031	17.859
23/32fraction	0.7188	18.256
47/64fraction	0.7344	18.653
3/4fraction	0.7500	19.050
49/64fraction	0.7656	19.447	Tap drill for 7/8-9 UNC; close fit for 3/4 screws
25/32fraction	0.7813	19.844	Free fit for 3/4 screws
51/64fraction	0.7969	20.241
13/16fraction	0.8125	20.637	Tap drill for 7/8-14 UNF
53/64fraction	0.8281	21.034
27/32fraction	0.8438	21.431
55/64fraction	0.8594	21.828
7/8fraction	0.8750	22.225	Tap drill for 1-8 UNC
57/64fraction	0.8906	22.622	Close fit for 7/8 screws
29/32fraction	0.9063	23.019	Free fit for 7/8 screws
59/64fraction	0.9219	23.416	Tap drill for 1-12 UNF
15/16fraction	0.9375	23.813
61/64fraction	0.9531	24.209
31/32fraction	0.9688	24.606
63/64fraction	0.9844	25.003	Tap drill for 1-1/8-7 UNC
1fraction	1.0000	25.400
1-1/64fraction	1.0156	25.797	Close fit for 1 screws
1-1/32fraction	1.0313	26.194	Free fit for 1 screws
1-3/64fraction	1.0469	26.591	Tap drill for 1-1/8-12 UNF
1-1/16fraction	1.0625	26.987
1-5/64fraction	1.0781	27.384
1-3/32fraction	1.0938	27.781
1-7/64fraction	1.1094	28.178	Tap drill for 1-1/4-7 UNC
1-1/8fraction	1.1250	28.575
1-9/64fraction	1.1406	28.972
1-5/32fraction	1.1563	29.369
1-11/64fraction	1.1719	29.766	Tap drill for 1-1/4-12 UNF
1-3/16fraction	1.1875	30.162
1-13/64fraction	1.2031	30.559
1-7/32fraction	1.2188	30.956	Tap drill for 1-3/8-6 UNC
1-15/64fraction	1.2344	31.353
1-1/4fraction	1.2500	31.750
1-17/64fraction	1.2656	32.147
1-9/32fraction	1.2813	32.544
1-19/64fraction	1.2969	32.941	Tap drill for 1-3/8-12 UNF
1-5/16fraction	1.3125	33.337
1-21/64fraction	1.3281	33.734
1-11/32fraction	1.3438	34.131	Tap drill for 1-1/2-6 UNC
1-23/64fraction	1.3594	34.528
1-3/8fraction	1.3750	34.925
1-25/64fraction	1.3906	35.322
1-13/32fraction	1.4063	35.719
1-27/64fraction	1.4219	36.116	Tap drill for 1-1/2-12 UNF
1-7/16fraction	1.4375	36.512
1-29/64fraction	1.4531	36.909
1-15/32fraction	1.4688	37.306
1-31/64fraction	1.4844	37.703
1-1/2fraction	1.5000	38.100
1-33/64fraction	1.5156	38.497
1-17/32fraction	1.5313	38.894
1-35/64fraction	1.5469	39.291
1-9/16fraction	1.5625	39.688	Tap drill for 1-3/4-5 UNC
1-37/64fraction	1.5781	40.084
1-19/32fraction	1.5938	40.481
1-39/64fraction	1.6094	40.878
1-5/8fraction	1.6250	41.275
1-41/64fraction	1.6406	41.672
1-21/32fraction	1.6563	42.069
1-43/64fraction	1.6719	42.466
1-11/16fraction	1.6875	42.862
1-45/64fraction	1.7031	43.259
1-23/32fraction	1.7188	43.656
1-47/64fraction	1.7344	44.053
1-3/4fraction	1.7500	44.450
1-49/64fraction	1.7656	44.847
1-25/32fraction	1.7813	45.244	Tap drill for 2-4.5 UNC
1-51/64fraction	1.7969	45.641
1-13/16fraction	1.8125	46.037
1-53/64fraction	1.8281	46.434
1-27/32fraction	1.8438	46.831
1-55/64fraction	1.8594	47.228
1-7/8fraction	1.8750	47.625
1-57/64fraction	1.8906	48.022
1-29/32fraction	1.9063	48.419
1-59/64fraction	1.9219	48.816
1-15/16fraction	1.9375	49.212
1-61/64fraction	1.9531	49.609
1-31/32fraction	1.9688	50.006
1-63/64fraction	1.9844	50.403
2fraction	2.0000	50.800

Drill sizes · smallest to largest · 234 drills

Drill

Inches

Common use

#80number

0.0135

0.343

#79number

0.0145

0.368

1/64fraction

0.0156

0.397

#78number

0.0160

0.406

#77number

0.0180

0.457

#76number

0.0200

0.508

#75number

0.0210

0.533

#74number

0.0225

0.571

#73number

0.0240

0.610

#72number

0.0250

0.635

#71number

0.0260

0.660

#70number

0.0280

0.711

#69number

0.0292

0.742

#68number

0.0310

0.787

1/32fraction

0.0313

0.794

#67number

0.0320

0.813

#66number

0.0330

0.838

#65number

0.0350

0.889

#64number

0.0360

0.914

#63number

0.0370

0.940

#62number

0.0380

0.965

#61number

0.0390

0.991

#60number

0.0400

1.016

#59number

0.0410

1.041

#58number

0.0420

1.067

#57number

0.0430

1.092

#56number

0.0465

1.181

3/64fraction

0.0469

1.191

Tap drill for #0-80 UNF

#55number

0.0520

1.321

#54number

0.0550

1.397

#53number

0.0595

1.511

Tap drill for #1-64 UNC, #1-72 UNF

1/16fraction

0.0625

1.587

#52number

0.0635

1.613

Close fit for #0 screws

#51number

0.0670

1.702

#50number

0.0700

1.778

Tap drill for #2-56 UNC, #2-64 UNF; free fit for #0 screws

#49number

0.0730

1.854

#48number

0.0760

1.930

Close fit for #1 screws

5/64fraction

0.0781

1.984

#47number

0.0785

1.994

Tap drill for #3-48 UNC

#46number

0.0810

2.057

Free fit for #1 screws

#45number

0.0820

2.083

Tap drill for #3-56 UNF

#44number

0.0860

2.184

#43number

0.0890

2.261

Tap drill for #4-40 UNC; close fit for #2 screws

#42number

0.0935

2.375

Tap drill for #4-48 UNF

3/32fraction

0.0938

2.381

#41number

0.0960

2.438

Free fit for #2 screws

#40number

0.0980

2.489

#39number

0.0995

2.527

#38number

0.1015

2.578

Tap drill for #5-40 UNC

#37number

0.1040

2.642

Tap drill for #5-44 UNF; close fit for #3 screws

#36number

0.1065

2.705

Tap drill for #6-32 UNC

7/64fraction

0.1094

2.778

#35number

0.1100

2.794

Free fit for #3 screws

#34number

0.1110

2.819

#33number

0.1130

2.870

Tap drill for #6-40 UNF

#32number

0.1160

2.946

Close fit for #4 screws

#31number

0.1200

3.048

1/8fraction

0.1250

3.175

#30number

0.1285

3.264

Close fit for #5 screws; free fit for #4 screws

#29number

0.1360

3.454

Tap drill for #8-32 UNC, #8-36 UNF; free fit for #5 screws

#28number

0.1405

3.569

9/64fraction

0.1406

3.572

#27number

0.1440

3.658

Close fit for #6 screws

#26number

0.1470

3.734

#25number

0.1495

3.797

Tap drill for #10-24 UNC; free fit for #6 screws

#24number

0.1520

3.861

#23number

0.1540

3.912

5/32fraction

0.1563

3.969

#22number

0.1570

3.988

#21number

0.1590

4.039

Tap drill for #10-32 UNF

#20number

0.1610

4.089

#19number

0.1660

4.216

#18number

0.1695

4.305

Close fit for #8 screws

11/64fraction

0.1719

4.366

#17number

0.1730

4.394

#16number

0.1770

4.496

Tap drill for #12-24 UNC; free fit for #8 screws

#15number

0.1800

4.572

#14number

0.1820

4.623

Tap drill for #12-28 UNF

#13number

0.1850

4.699

3/16fraction

0.1875

4.762

#12number

0.1890

4.801

#11number

0.1910

4.851

#10number

0.1935

4.915

#9number

0.1960

4.978

Close fit for #10 screws

#8number

0.1990

5.055

#7number

0.2010

5.105

Tap drill for 1/4-20 UNC; free fit for #10 screws

13/64fraction

0.2031

5.159

#6number

0.2040

5.182

#5number

0.2055

5.220

#4number

0.2090

5.309

#3number

0.2130

5.410

Tap drill for 1/4-28 UNF

7/32fraction

0.2188

5.556

#2number

0.2210

5.613

Close fit for #12 screws

#1number

0.2280

5.791

Free fit for #12 screws

Aletter

0.2340

5.944

15/64fraction

0.2344

5.953

Bletter

0.2380

6.045

Cletter

0.2420

6.147

Dletter

0.2460

6.248

1/4fraction

0.2500

6.350

Eletter

0.2500

6.350

Fletter

0.2570

6.528

Tap drill for 5/16-18 UNC; close fit for 1/4 screws

Gletter

0.2610

6.629

17/64fraction

0.2656

6.747

Hletter

0.2660

6.756

Free fit for 1/4 screws

Iletter

0.2720

6.909

Tap drill for 5/16-24 UNF

Jletter

0.2770

7.036

Kletter

0.2810

7.137

9/32fraction

0.2813

7.144

Lletter

0.2900

7.366

Mletter

0.2950

7.493

19/64fraction

0.2969

7.541

Nletter

0.3020

7.671

5/16fraction

0.3125

7.938

Tap drill for 3/8-16 UNC

Oletter

0.3160

8.026

Pletter

0.3230

8.204

Close fit for 5/16 screws

21/64fraction

0.3281

8.334

Qletter

0.3320

8.433

Tap drill for 3/8-24 UNF; free fit for 5/16 screws

Rletter

0.3390

8.611

11/32fraction

0.3438

8.731

Sletter

0.3480

8.839

Tletter

0.3580

9.093

23/64fraction

0.3594

9.128

Uletter

0.3680

9.347

Tap drill for 7/16-14 UNC

3/8fraction

0.3750

9.525

Vletter

0.3770

9.576

Wletter

0.3860

9.804

Close fit for 3/8 screws

25/64fraction

0.3906

9.922

Tap drill for 7/16-20 UNF

Xletter

0.3970

10.084

Free fit for 3/8 screws

Yletter

0.4040

10.262

13/32fraction

0.4063

10.319

Zletter

0.4130

10.490

27/64fraction

0.4219

10.716

Tap drill for 1/2-13 UNC

7/16fraction

0.4375

11.112

29/64fraction

0.4531

11.509

Tap drill for 1/2-20 UNF; close fit for 7/16 screws

15/32fraction

0.4688

11.906

Free fit for 7/16 screws

31/64fraction

0.4844

12.303

Tap drill for 9/16-12 UNC

1/2fraction

0.5000

12.700

33/64fraction

0.5156

13.097

Tap drill for 9/16-18 UNF; close fit for 1/2 screws

17/32fraction

0.5313

13.494

Tap drill for 5/8-11 UNC; free fit for 1/2 screws

35/64fraction

0.5469

13.891

9/16fraction

0.5625

14.287

37/64fraction

0.5781

14.684

Tap drill for 5/8-18 UNF; close fit for 9/16 screws

19/32fraction

0.5938

15.081

Free fit for 9/16 screws

39/64fraction

0.6094

15.478

5/8fraction

0.6250

15.875

41/64fraction

0.6406

16.272

Close fit for 5/8 screws

21/32fraction

0.6563

16.669

Tap drill for 3/4-10 UNC; free fit for 5/8 screws

43/64fraction

0.6719

17.066

11/16fraction

0.6875

17.462

Tap drill for 3/4-16 UNF

45/64fraction

0.7031

17.859

23/32fraction

0.7188

18.256

47/64fraction

0.7344

18.653

3/4fraction

0.7500

19.050

49/64fraction

0.7656

19.447

Tap drill for 7/8-9 UNC; close fit for 3/4 screws

25/32fraction

0.7813

19.844

Free fit for 3/4 screws

51/64fraction

0.7969

20.241

13/16fraction

0.8125

20.637

Tap drill for 7/8-14 UNF

53/64fraction

0.8281

21.034

27/32fraction

0.8438

21.431

55/64fraction

0.8594

21.828

7/8fraction

0.8750

22.225

Tap drill for 1-8 UNC

57/64fraction

0.8906

22.622

Close fit for 7/8 screws

29/32fraction

0.9063

23.019

Free fit for 7/8 screws

59/64fraction

0.9219

23.416

Tap drill for 1-12 UNF

15/16fraction

0.9375

23.813

61/64fraction

0.9531

24.209

31/32fraction

0.9688

24.606

63/64fraction

0.9844

25.003

Tap drill for 1-1/8-7 UNC

1fraction

1.0000

25.400

1-1/64fraction

1.0156

25.797

Close fit for 1 screws

1-1/32fraction

1.0313

26.194

Free fit for 1 screws

1-3/64fraction

1.0469

26.591

Tap drill for 1-1/8-12 UNF

1-1/16fraction

1.0625

26.987

1-5/64fraction

1.0781

27.384

1-3/32fraction

1.0938

27.781

1-7/64fraction

1.1094

28.178

Tap drill for 1-1/4-7 UNC

1-1/8fraction

1.1250

28.575

1-9/64fraction

1.1406

28.972

1-5/32fraction

1.1563

29.369

1-11/64fraction

1.1719

29.766

Tap drill for 1-1/4-12 UNF

1-3/16fraction

1.1875

30.162

1-13/64fraction

1.2031

30.559

1-7/32fraction

1.2188

30.956

Tap drill for 1-3/8-6 UNC

1-15/64fraction

1.2344

31.353

1-1/4fraction

1.2500

31.750

1-17/64fraction

1.2656

32.147

1-9/32fraction

1.2813

32.544

1-19/64fraction

1.2969

32.941

Tap drill for 1-3/8-12 UNF

1-5/16fraction

1.3125

33.337

1-21/64fraction

1.3281

33.734

1-11/32fraction

1.3438

34.131

Tap drill for 1-1/2-6 UNC

1-23/64fraction

1.3594

34.528

1-3/8fraction

1.3750

34.925

1-25/64fraction

1.3906

35.322

1-13/32fraction

1.4063

35.719

1-27/64fraction

1.4219

36.116

Tap drill for 1-1/2-12 UNF

1-7/16fraction

1.4375

36.512

1-29/64fraction

1.4531

36.909

1-15/32fraction

1.4688

37.306

1-31/64fraction

1.4844

37.703

1-1/2fraction

1.5000

38.100

1-33/64fraction

1.5156

38.497

1-17/32fraction

1.5313

38.894

1-35/64fraction

1.5469

39.291

1-9/16fraction

1.5625

39.688

Tap drill for 1-3/4-5 UNC

1-37/64fraction

1.5781

40.084

1-19/32fraction

1.5938

40.481

1-39/64fraction

1.6094

40.878

1-5/8fraction

1.6250

41.275

1-41/64fraction

1.6406

41.672

1-21/32fraction

1.6563

42.069

1-43/64fraction

1.6719

42.466

1-11/16fraction

1.6875

42.862

1-45/64fraction

1.7031

43.259

1-23/32fraction

1.7188

43.656

1-47/64fraction

1.7344

44.053

1-3/4fraction

1.7500

44.450

1-49/64fraction

1.7656

44.847

1-25/32fraction

1.7813

45.244

Tap drill for 2-4.5 UNC

1-51/64fraction

1.7969

45.641

1-13/16fraction

1.8125

46.037

1-53/64fraction

1.8281

46.434

1-27/32fraction

1.8438

46.831

1-55/64fraction

1.8594

47.228

1-7/8fraction

1.8750

47.625

1-57/64fraction

1.8906

48.022

1-29/32fraction

1.9063

48.419

1-59/64fraction

1.9219

48.816

1-15/16fraction

1.9375

49.212

1-61/64fraction

1.9531

49.609

1-31/32fraction

1.9688

50.006

1-63/64fraction

1.9844

50.403

2fraction

2.0000

50.800

Number, letter and fraction drills

Inch drills come in three overlapping series. Number drills run from #80 (0.0135 in) up to #1 (0.228 in): the higher the number, the smaller the drill. Letter drills carry on from A (0.234 in) to Z (0.413 in). Fractional drills go up in 64ths of an inch. Put together in order, they give a drill every few thousandths through the small sizes, which is why tap drill and clearance hole charts call for number and letter drills so often.

Millimetre sizes are the inch size times 25.4. For the closest inch drill to a metric size, type it in the finder above with Units set to millimetres.

Common questions

What size is a #7 drill?

0.201 in (5.105 mm). It is the tap drill for a 1/4-20 thread. A #29 (0.136 in) is the tap drill for 8-32, a #21 (0.159 in) for 10-32, and a #25 (0.1495 in) for 10-24.

What size is an F drill?

0.257 in (6.528 mm). It is the tap drill for 5/16-18 and the close fit clearance hole for a 1/4 in screw; an H (0.266 in) gives a free fit.

What drill is closest to 5 mm?

A #9 (0.196 in, 4.978 mm). Type any size into the finder, in inches or millimetres, to see the closest drill and the ones either side of it.

Are fractional drills the same size as number drills?

Only one pair is exactly the same: 1/4 in and the E drill, both 0.250 in. Several others are within a few ten-thousandths of each other, such as #28 (0.1405) and 9/64 (0.1406), #42 (0.0935) and 3/32 (0.0938), and K (0.281) and 9/32 (0.2813). Others fall between two drills of another series: 5/32 (0.1563) sits between #23 and #22. That is why one chart in order is handier than three separate lists.

Drill size chart