You know what they say: measure twice, cut once. This goes for many things in life, but it’s especially true for woodworking and plumbing projects. Apart from a standard ruler and tape measure, there are two extremely beneficial tools you can use to make flawless measurements every time—they’re called calipers and micrometers.
We know what you’re thinking. “What’s the difference? And aren’t there several types of calipers?” In this guide, we’re going to address these questions to help you decide which of the two will work best for whatever upcoming project you may have.
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Calipers vs. Micrometers
Calipers are precision measurement tools that typically give readouts of up to one-thousandth of an inch. They are used in a wide range of applications, though you’ll mainly find them being used by plumbers, woodworkers, and grease monkeys, by both DIY-ers and professionals. A caliper serves four main functions, namely measuring short distances between two sides of an object, measuring inner and external thicknesses, measuring depth, and measuring steps.
Calipers come with jaws or legs that can be adjusted by turning a thumbscrew. When the jaws are set in the appropriate position when taking distance, thickness, and step measurements, they can be locked into place by turning the lock screw. The measured depth has a depth rod that pops out of the bottom end of the tool.
Similar to calipers, micrometers are precision measurement devices that give extremely accurate readouts, also up to one-thousandth of an inch. However, the biggest difference between the two is that micrometers are one-trick ponies that measure distance, thickness, OR depth, not all three. This means you’ll have to get a set of three different micrometers to perform the same tasks as a multi-purpose caliper.
A micrometer’s design is nearly identical to a caliper’s, so much so that their names are often used interchangeably. However, because they perform a single task, they only come with one pair of jaws for measuring either thickness or distance, or they have long rods that twist out of the bottom for depth readings.
Types of Calipers: Digital vs. Dial vs. Vernier
Calipers can be divided into three main types: digital, dial, and Vernier. The most significant difference between the three is their measurement scales. Here’s a quick rundown of each type.
Digital calipers do not feature the same rack and pinion mechanism found in dials and Vernier models. Instead, they’re built with a microprocessor that calculates the distance of the two jaws relative to each other and displays the figure in a digital display.
Dial calipers have a dial display that shows the final measurement readouts with an indicator needle. The final readout is typically one-thousandth of an inch, though there is one-hundredth of an inch display. This reading is added to the measurement of the scale between the two jaws.
Vernier calipers consist of two scales—the main scale not unlike a standard ruler and a Vernier scale. The “0” mark on the lower jaw indicates were to read the measurement on the main scale, whereas the lines that line up best on the Vernier scale are used to measure tenths of a millimeter.