When building your own bass, math is involved and there’s no way around it. You’re going to be measuring things and that’s just the way it is.
More often than not you’re going to have to deal with both statute (inches) and metric (millimeters) measurements when putting a bass together, so it’s good to know how to convert either to either as you’re putting your build together.
Here’s a quick guide you can refer to whenever you need to convert one to the other.
Have a fraction measurement and need a decimal? Divide the nominator (number on top) by the denominator (number on bottom). Which conveniently is exactly what it looks like you should do with a fraction.
Example: 11/16 = 0.6875″
Need that same measurement in millimeters? Multiply by the number of millimeters in an inch, 25.4.
Example 0.6875″ x 25.4 = 17.4625mm (slightly less than 17.5mm)
Starting with metric instead? Reverse it and divide by 25.4.
Example: 16mm / 25.4 = 0.629″
Need that in fractional inches? Multiply by your desired denominator. The result is the nominator.
Example: 0.629″ x 8 = 5.032 so slightly greater than 5/8″.
And yes, when converting inches to millimeters and vice versa, you’re going to run into “slightly” often. Converting 16mm to inches is a good example of this because you’re technically getting 5.032/8ths of an inch.
… which is why the metric system makes more sense! You don’t have any stupid fractions! And who decided that inch goes to foot goes to yards goes to miles? The metric system goes by tens and is SOOO much easier!
Handy!