Ian Glen

Screw Heads

Screw heads styles and common sizes.

Slot (Flat Blade)

The width of the head is the size.

Metric (mm)English (in)
0.70.028
0.90.035
1
1.30.050
1.5
1/16
25/64
3/32
2.5
7/64
3
1/8
3.5
9/64
45/32
4.5
3/16
5
5.5
7/32
6
1/4
6.5
85/16
10
12

Phillips

Size codes are arbitrary. Larger numbers indicate larger sizes.

Size Code
PH0000
PH000
PH00
PH0
PH1
PH2
PH3
PH4

Hex (Allen)

The distance between two parallel faces is the size.

Metric (mm)English (in)Security Version?
0.70.028
0.90.035
1.30.050
1.5
1/16
25/64
3/32
2.5
7/64
3
1/8
3.5
9/64
45/32
4.5
3/16
5
5.5
7/32
6
1/4
85/16
3/8
10

Torx (Star)

Size codes are arbitrary. Larger numbers indicate larger sizes.

Point-to-point distance
Size CodeinmmSecurity Version?
T10.0310.81
T20.0360.93
T30.0461.10
T40.0501.28
T50.0551.42
T60.0661.70
T70.0781.99
T80.0902.31
T90.0982.50
T100.1072.74
T150.1283.27
T200.1513.86
T250.1734.43
T270.1954.99
T300.2165.52
T400.2606.65
T450.3067.82
T500.3468.83
T550.44011.22
T600.51913.25
T700.61015.51
T800.69017.54
T900.78419.92
T1000.87122.13