Hole sizes for screw cutting Taps

METRIC

M20

1.60

M25

2.10

M30

2.50

M3.5

3.00

M4.0

3.30

M5.0

4.20

M6.0

5.10

M7.0

6.00

M8.0

6.80

M10.0

8.50

M12.0

10.2

BA

10 BA

1.40

8 BA

1.80

6 BA

2.30

4 BA

3.00

2 BA

4.00

0 BA

5.10

UNF

10 UNF

4.10

1/4 UNF

5.50

5/16 UNF

6.90

3/8 UNF

8.50

1/2 UNF

11.5

ALL HOLE SIZES IN MM

BSW

3/16 BSW

3.70

1/4 BSW

5.10

5/16 BSW

6.50

3/8 BSW

7.90

1/2 BSW

10.5

5/8 BSW

13.5

3/4 BSW

16.2

METRIC FINE

M20

18.5

M25

23.5

UNC

1/4 UNC

5.10

5/16 UNC

6.60

3/8 UNC

8.00

1/2 UNC

10.8

BSF

1/4 BSF

5.30

5/16 BSF

6.80

3/8 BSF

8.30

1/2 BSF

11.0