I was working in my shop one day when a cut came out slightly off, but I couldn’t tell with the naked eye. I had to break out my calipers to find out what the problem was, and it was less than 0.05 of an inch—it was a millimeter. That’s when I realized it was time to ditch the imperial measurement system for something more accurate: metric.
Metric is just easier to work with
Fractions are fine until they’re not
Like most Americans, I grew up using the imperial measurement systems. Feet, inches, miles—the whole nine yards. As a kid, I always thought the metric system was inferior and more difficult to understand, but I was simply wrong.
With the imperial system, everything is measured in fractions. 1/8”, 3/16”, 1/3-mile, and many other measurements are simply done with fractions instead of decimals. Decimals are, objectively, easier to understand. Imperial can work with decimals, and I eventually had to learn all of that too—fractions have a decimal value, after all.
The fractions aren’t the hardest part of the imperial system, though, it’s the fact that nothing relates to each other. An inch can be broken down as far as you want fractionally—eights, sixteenths, hundredths, and so on. But 1 foot has 12 inches in it. 1 yard has 3 feet in it. 1 mile has 5,280 feet (or 1,760 yards) in it. There’s no rhyme or reason for why the measurements are the way that they are, at least, not numerically.
However, metric is just easier to understand because it’s decimal first, fraction second. Being a base-10 measurement system, every measurement converts to another. A millimeter is one thousandth of a meter. A centimeter is one hundredth of a meter. A meter is, well, a meter, or 100 centimeters, or 1,000 millimeters.
When I first started woodworking, I was still using the imperial system because it was what I knew. When I started to need a higher level of accuracy, I found the imperial system lacking. Then, when I got into 3D printing and CNC machining, I realized that the metric system was the only way to take accurate measurements.
When a millimeter actually matters
Precise measurement doesn’t happen on a tape measure with inches
When doing CNC machining (computer numerical control, or simply computer-controlled), accuracy is paramount. My first CNC system was a CNC router that I used for woodworking, then I got a 3D printer, and eventually laser engravers. What I found after using all three forms of systems is that imperial measurement just wasn’t accurate enough.
With metric, I can measure down to the millimeter—of which there are 25.4 in one inch. That means I would have to measure in 1/25 of an inch to get as accurate as I can with a millimeter, and almost no tape measure actually goes down that far. The most you’ll normally find is 1/16 of an inch or 1/32 if your tape measure is super accurate.
Once I moved to using the metric system for measurements on my machines, I realized just how inaccurate the imperial system was. My work started to become better, I was nesting jobs better, and everything just looked… better.
At the end of the day, a single millimeter (or 1/25th of an inch, or 0.04 of an inch) can make all the difference when you’re trying to create something with a high degree of accuracy.
Once I went metric, imperial started to feel clunky
It takes time, but the switch is worth it
At first, I used both metric and imperial in my workshop. I used metric when I needed accuracy, and imperial when I was measuring something larger or when I was okay with a bit of inaccuracy.
Eventually, though, I moved to using metric almost exclusively. It definitely took a few years of using before my brain started to think in metric, but now I prefer metric for all measurements. I still use imperial when I have to, but metric is my default.
While I used to buy tape measures that only had imperial measurements on them, I’ve gone back to the old ways of buying tape measures that have both imperial and metric on them. This lets me use metric most of the time, but has the fallback of imperial if I need it (or if someone besides me is using the tape measure).
There’s a reason the entire globe uses the metric system
I really wish the US would move to the metric system. There are only three countries on the globe still using the imperial system—the USA, Liberia, and Myanmar. However, both Liberia and Myanmar are working toward using the metric system, which would leave the US out in the cold as the lone user of the imperial system.
Sadly, I don’t think it’ll ever happen on a nationwide scale, so I’ll just stick to using the metric system in my workshop and keep my imperial knowledge in my back pocket.
