Metric to US Conversion Table for common fastener sizes
Below is a table common fastener sizes and lengths and their US (Inch) decimal and closest fraction equivalent.
Note - Metric screw diameters usually start with "M" (M3, M4, M5...), for this chart you can just drop the 'M' from the front and add an extra at the back (M3 = 3mm, M4 = 4mm...).
|
Metric |
US Decimal | Closest* |
Metric |
US Decimal | Closest* | |
| 1.5mm | 0.0591” | 1/16 | 55mm | 2.1654” | 2-3/16 | |
| 2mm | 0.0787” | 5/64 | 60mm | 2.3622” | 2-3/8 | |
| 2.5mm | 0.0984” | 3/32 | 65mm | 2.5591” | 2-9/16 | |
| 3mm | 0.1181” | 1/8 | 70mm | 2.7559” | 2-3/4 | |
| 4mm | 0.1575” | 5/32 | 75mm | 2.9528” | 2-15/16 | |
| 5mm | 0.1969” | 3/16 | 80mm | 3.1496” | 3-1/8 | |
| 6mm | 0.2362” | 1/4 | 85mm | 3.3465” | 3-3/8 | |
| 8mm | 0.3150” | 5/16 | 90mm | 3.5433” | 3-9/16 | |
| 10mm | 0.3937” | 13/32 | 95mm | 3.7402” | 3-3/4 | |
| 12mm | 0.4724” | 15/32 | 100mm | 3.9370” | 3-15/16 | |
| 14mm | 0.5512” | 9/16 | 110mm | 4.3307” | 4-5/16 | |
| 15mm | 0.5906” | 19/32 | 120mm | 4.7244” | 4-3/4 | |
| 16mm | 0.6299” | 5/8 | 125mm | 4.9213” | 4-15/16 | |
| 18mm | 0.7087” | 23/32 | 130mm | 5.1181” | 5-1/8 | |
| 20mm | 0.7874” | 25/32 | 140mm | 5.5118” | 5-1/2 | |
| 22mm | 0.8661” | 7/8 | 150mm | 5.9055” | 5-7/8 | |
| 25mm | 0.9843” | 1 | 160mm | 6.2992” | 6-5/16 | |
| 28mm | 1.1024” | 1-1/8 | 170mm | 6.6929” | 6-11/16 | |
| 30mm | 1.1811” | 1-3/16 | 175mm | 6.8898” | 6-7/8 | |
| 35mm | 1.3780” | 1-3/8 | 180mm | 7.0866” | 7-1/16 | |
| 40mm | 1.5748” | 1-9/16 | 190mm | 7.4803” | 7-1/2 | |
| 45mm | 1.7717” | 1-3/4 | 200mm | 7.8740” | 7-7/8 | |
| 50mm | 1.9685” | 1-15/16 |
* Closest US fraction to metric size