Metric Bolt Conversion
The charts below show metric bolt conversions to standard bolt conversions and DIN numbers for fasteners.
To assist in ordering, we offer metric bolt conversion data for industrial bolts/rods, machine screws, and small-diameter fasteners, including approximate equivalency and common DIN numbers.
Diameter/Decimal/Metric Chart for Small Diameter Fasteners
| Gauge / Diameter | Decimal (in) | Decimal (mm) |
|---|---|---|
| No.0000 | 0.021 | 0.53 |
| No.000 | 0.034 | 0.86 |
| No.00 | 0.047 | 1.19 |
| No.0 | 0.06 | 1.524 |
| No.1 | 0.073 | 1.854 |
| No.2 | 0.086 | 2.184 |
| No.3 | 0.099 | 2.515 |
| No.4 | 0.112 | 2.845 |
| No.5 | 0.125 | 3.175 |
| No.6 | 0.138 | 3.505 |
| No.8 | 0.164 | 4.166 |
| No.10 | 0.19 | 4.826 |
| No.12 | 0.216 | 5.484 |
Fastener Conversion Chart
| Inch Equivalent - UNC | Inch Equivalent - UNF | Metric Size - Pitch ISO & IFI Rec. |
|---|---|---|
| 1- 64 | 1- 72 | M2x 0.4 |
| 3- 48 | 3- 56 | M2.5x 0.45 |
| 4- 40 | 4- 48 | M3x .5 |
| 6- 32 | 6- 40 | M3.5x .6 |
| 8- 32 | 8- 36 | M4x .7 |
| 10- 24 | 10- 32 | M5x .8 |
| 1/4- 20 | 1/4- 28 | M6x 1 |
| 5/16-18 | 5/16- 24 | M8x 1.25 |
| 3/8-16 | 3/8- 24 | M10x 1.5 |
| 7/16-14 | 7/16- 20 | M12x 1.75 |
| 1/2- 13 | 1/2- 20 | M14x 2 |
| 5/8- 11 | 5/8- 18 | M18x 2 |
| 3/4- 10 | 3/4- 16 | M20x 2.5 |
| 1- 8 | 1-12 | M24x 3 |
| 1-1/4- 7 | 1-1/8- 12 | M30x 3.5 |
| 1-1/2- 6 | 1-1/4- 12 | M36x 4 |
Approximate Equivalency Chart Metric/US Roughly Equivalent US Bolt Materials
| Metric Nut Class | SAE J429 Normally Used | Grades | ASTM Grades |
|---|---|---|---|
| 4.6 | 4or 5 | 1 | A307,Grade A |
| 4.8 | 4or 5 | 2 | . |
| 5.8 | 5 | 2 | . |
| 8.8 | 8 | 5 | A325,A449 |
| 9.8 | 9 | 5+ | A193,B7 and B16 |
| 10.9 | 10or 12 | 8 | A490,A354, Grade 8D |
| 12.9 | 10or 12 | . | A540;B21 through B24 |
Common DIN Numbers for Metric Fasteners
| DIN | Hex Capscrews |
|---|---|
| 931 | Coarse thread pitch partially threaded (specify grade) |
| 933 | Coarse thread pitch fully threaded (specify grade) |
| 930 | Fine thread pitch partially threaded (specify grade) |
| 961 | Fine thread pitch fully threaded (specify grade) |
| DIN | Products |
|---|---|
| 912 | Socket head capscrews (normally GR 12.9 and coarse thread) |
| 7991 | Flat head socket capscrews (normally GR 12.9 and coarse thread) |
| 916 | Socket setscrews (normally GR 12.9 and coarse thread) |
| DIN | Nuts |
|---|---|
| 934 | Hex nuts (specify pitch and class) |
| 985 | Nylon insert locknuts (specify pitch and class) |
| 980V | All metal locknuts (specify pitch and class) |
| DIN | Washers |
|---|---|
| 125 | Flatwashers |
| 127 | Lockwashers |
| 980V | All metal locknuts (specify pitch and class) |
| DIN | Machine Screws |
|---|---|
| 7985 | Pan head Phillips drive zinc plated |
| 965 | Flat head Phillips drive zinc plated |
| DIN | Threaded Rod |
|---|---|
| 975 | All threaded rod (normally 1 meter lengths, specify grade and pitch) |
