How to Convert Metric Bolts

A bolt is a threaded metal fastener that is used to securely adjoin mechanical pieces of one larger system. Although used for similar applications, bolts are distinguished from screws by their flat bottoms. There are many different types of bolts, each of which is identified by five separate features--the head, the material, the bolt diameter, the bolt length and the thread count. The latter three features can be given in terms of metric or US standard measurements. When US standard bolts are the only type available for a metric application, a conversion between the two systems is necessary to identify the correct bolt.

Instructions

1

Identify the metric bolt that you wish to convert to the standard measure. This should be listed in the manufacturer's specifications for the parts that is are to be fastened. The most important value is the diameter, but some consideration must also be given to the length of the bolt. The thread count must be considered when the fastener hole is threaded as well.

2

Divide the metric values that are to be converted by the conversion factor 25.4 mm/inch. In this calculation, the metric value vanishes and all that is left is the standard (inch) value.

3

Round the diameter conversion to the nearest 32nd of an inch. To get the standard value from decimal form into a fractional form of 32nds, simply multiply the decimal value by 32. This shall be the numerator of a fraction whose denominator is 32. If the numerator still contains decimal numbers, round to the nearest whole number.

4

Identify the US standard bolt whose measurements most closely match those of the metric bolt that has been converted. This bolt will be the US standard-based replacement for the metric fastener.