If you are using a digital caliper, the measurement should be displayed on an electronic screen, typically with the option to switch between mm (millimeters) and inches (in). Before you take the measurement, close the larger jaws completely and press the Zero, Tare or ABS button to set the closed position to a value of zero.

Watch the jaws closely to make sure you are not pushing a fine adjustment screw, which opens and closes the jaws by small amounts.

For example, if the sliding scale’s 0 is at 0. 9mm on the fixed scale, write down “zero error: +0. 9 mm. "

For example, if the sliding scale’s 0 is at 0. 9mm on the fixed scale, write down “zero error: +0. 9 mm. "

With jaws closed, look for a mark on the sliding scale that lines up exactly with a value on the fixed scale Move the sliding scale so that mark lines up with the next highest value. Repeat until the sliding scale 0 is to the right of the fixed scale 0. Note the amount of distance moved. Read the value on the fixed scale that lines up with the sliding scale’s 0. Subtract the amount of distance moved from the value you just read. Write down this zero error, including the negative sign. For example, the 7 on the sliding scale lines up with the 5mm mark on the fixed scale. Move the sliding scale until it is further right than the fixed scale, then line up the 7 with the next fixed-scale mark: 7mm. Note that you moved a distance of 7 - 5 = 2mm. The sliding scale’s 0 is now located at the 0. 7mm mark. The zero error is equal to 0. 7mm - 2mm = -1. 3mm.

With jaws closed, look for a mark on the sliding scale that lines up exactly with a value on the fixed scale Move the sliding scale so that mark lines up with the next highest value. Repeat until the sliding scale 0 is to the right of the fixed scale 0. Note the amount of distance moved. Read the value on the fixed scale that lines up with the sliding scale’s 0. Subtract the amount of distance moved from the value you just read. Write down this zero error, including the negative sign. For example, the 7 on the sliding scale lines up with the 5mm mark on the fixed scale. Move the sliding scale until it is further right than the fixed scale, then line up the 7 with the next fixed-scale mark: 7mm. Note that you moved a distance of 7 - 5 = 2mm. The sliding scale’s 0 is now located at the 0. 7mm mark. The zero error is equal to 0. 7mm - 2mm = -1. 3mm.

For example, if your zero error is +0. 9mm, and you take a measurement that reads 5. 52mm, the actual value is 5. 52 - 0. 9 = 4. 62mm. For example, if your zero error is -1. 3mm, and you take a measurement that reads 3. 20mm, the actual value is 3. 20 - (-1. 3) = 3. 20 + 1. 3 = 4. 50mm.

Slide the scale to open or close the jaws. If your caliper has a fine adjustment screw, you can use this to make more precise adjustments.

Find the 0 value on the smaller, sliding scale, next to the fixed scale you are using. On the fixed scale, find the nearest mark to the left of that 0, or exactly on it. Read that mark’s value just like you would read a ruler – but note that the imperial side of a caliper divides each inch into tenths, not sixteenths as most rulers do.

The value of the fixed-scale mark makes no difference. You only need to read the value on the sliding scale.

For example, your fixed scale measures 1. 3 and is marked “inches. " Your sliding scale measures 4. 3 and is marked “0. 01 inches,” meaning it represents 0. 043 inches. The exact measurement is 1. 3 inches + 0. 043 inches - 1. 343 inches. If you found a zero error earlier, don’t forget to subtract it from your measurement.

The scale should be labeled with a unit, typically cm (centimeters) or in (inches). Note that the inches scale of a caliper is typically an engineer’s scale, with each inch divided into ten parts (0.

  1. or five parts (0. 2). This is different from most rulers, which display sixteenths or eighths of an inch.

For example, the fixed scale displays 5. 5 and is labeled cm. The needle on the dial points to 9. 2 and is labeled 0. 001 cm, so this represents 0. 0092 cm. Add them together to get a measurement of 5. 5092 cm. Unless you are working on a project that requires extreme precision, you can probably round this to 5. 51 cm.