Wrench & Hex-Key Size Reference
Printable shop wall chart: Wrench & Hex-Key Size Reference. Free letter-size PDF to print and post at the counter; 25 x 36 inch poster version available.
Inch
| Size | Hex cap screw | Heavy hex | Socket head key | Button / flat key |
|---|---|---|---|---|
| #10 | - | - | 5/32 | 1/8 |
| 1/4 | 7/16 | - | 3/16 | 5/32 |
| 5/16 | 1/2 | - | 1/4 | 3/16 |
| 3/8 | 9/16 | - | 5/16 | 7/32 |
| 7/16 | 5/8 | - | 3/8 | 1/4 |
| 1/2 | 3/4 | 7/8 | 3/8 | 5/16 |
| 5/8 | 15/16 | 1-1/16 | 1/2 | 3/8 |
| 3/4 | 1-1/8 | 1-1/4 | 5/8 | 1/2 |
| 7/8 | 1-5/16 | 1-7/16 | 3/4 | - |
| 1 | 1-1/2 | 1-5/8 | 3/4 | - |
Metric (mm)
| Size | Hex head ISO (DIN) | Socket head key | Button key | Flat head key |
|---|---|---|---|---|
| M4 | 7 | 3 | 2.5 | 2.5 |
| M5 | 8 | 4 | 3 | 3 |
| M6 | 10 | 5 | 4 | 4 |
| M8 | 13 | 6 | 5 | 5 |
| M10 | 16 (17) | 8 | 6 | 6 |
| M12 | 18 (19) | 10 | 8 | 8 |
| M14 | 21 (22) | 12 | - | 10 |
| M16 | 24 | 14 | 10 | 10 |
| M20 | 30 | 17 | - | 12 |
| M22 | 34 (32) | 17 | - | - |
DIN sizes in brackets where they differ from ISO. Heavy hex shown for common structural sizes (heavy hex exists from 1/4 in). Verify key sizes for small button and flat heads against the maker.
These tables carry the same figures as the printed sheet below.
The printed sheet
25 x 36 inch poster version
For the full-size shop poster, tell us where to send it.
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Text version of this sheet
WRENCH: ACROSS FLATS
HEX KEY: SOCKET SIZE
Wrench across flats for hex heads · hex key for socket screws
Inch
Size
Hex cap screw
Heavy hex
Socket head key
Button / flat key
#10
-
-
5/32
1/8
1/4
7/16
-
3/16
5/32
5/16
1/2
-
1/4
3/16
3/8
9/16
-
5/16
7/32
7/16
5/8
-
3/8
1/4
1/2
3/4
7/8
3/8
5/16
5/8
15/16
1-1/16
1/2
3/8
3/4
1-1/8
1-1/4
5/8
1/2
7/8
1-5/16
1-7/16
3/4
-
1
1-1/2
1-5/8
3/4
-
Metric (mm)
Size
Hex head ISO (DIN)
Socket head key
Button key
Flat head key
M4
7
3
2.5
2.5
M5
8
4
3
3
M6
10
5
4
4
M8
13
6
5
5
M10
16 (17)
8
6
6
M12
18 (19)
10
8
8
M14
21 (22)
12
-
10
M16
24
14
10
10
M20
30
17
-
12
M22
34 (32)
17
-
-
DIN sizes in brackets where they differ from ISO. Heavy hex shown for common structural sizes (heavy hex exists from 1/4 in). Verify key sizes for small button and flat heads against the
maker.
The Fastener App | TheFastenerApp.com
Fastener Guide reference FG-2CC321 · thefastenerapp.com/fastener-guide/wall-charts/wrench-and-hex-key-size-reference · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
