Imperial To Metric Screw Conversion Chart
Those of us of a certain age still refer to screw sizes as imperial – we often hear the words can I have a box of 1”x 8’s please?
Many manufacturers still market screws that way, but for those of you who find it frustrating buying in metric, here’s a handy conversion chart.
| IMPERIAL SIZE (NO X INCH) | METRIC SIZE (MM APPROX.) |
| 4 x 1/2 | 3.0 x 12 |
| 4 x 3/4 | 3.0 x 20 |
| 4 x 1 | 3.0 x 25 |
| 6 x 1/2 | 3.5 x 12 |
| 6 x 5/8 | 3.5 x 16 |
| 6 x 3/4 | 3.5 x 20 |
| 6 x 1 | 3.5 x 25 |
| 6 x 1 1/4 | 3.5 x 30 |
| 8 x 3/4 | 4.0 x 20 |
| 8 x 1 | 4.0 x 25 |
| 8 x 1 1/4 | 4.0 x 30 |
| 8 x 1 1/2 | 4.0 x 40 |
| 8 x 1 3/4 | 4.0 x 45 |
| 8 x 2 | 4.0 x 50 |
| 8 x 2 1/2 | 4.0 x 60 |
| 8 x 2 3/4 | 4.0 x 70 |
| 10 x 1 1/4 | 5.0 x 30 |
| 10 x 1 1/2 | 5.0 x 40 |
| 10 x 2 | 5.0 x 50 |
| 10 x 2 1/2 | 5.0 x 60 |
| 10 x 2 3/4 | 5.0 x 70 |
| 10 x 3 | 5.0 x 80 |
| 10 x 3 1/2 | 5.0 x 90 |
| 10 x 4 | 5.0 x 100 |
| 12 x 2 | 6.0 x 50 |
| 12 x 2 1/2 | 6.0 x 60 |
| 12 x 2 3/4 | 6.0 x 70 |
| 12 x 3 | 6.0 x 80 |
| 12 x 3 1/2 | 6.0 x 90 |
| 12 x 4 | 6.0 x 100 |