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