How to Read a Micrometer
- 1). Know the parts of the micrometer before you read it. The micrometer is divided into the sleeve and the thimble. Notice that the sleeve's horizontal position contains numbers 0.1 inch apart, and tick marks 0.025 inches apart. View the numbers on the thimble, which are vertically listed. Count each tick on the thimble as “0.001” inches apart. If you have a vernier ruler on your micrometer, read each tick on that ruler as 0.0001 inches apart. Notice that the vernier is also vertical, and is right next to the numbers on the thimble.
- 2). Read from the sleeve of the micrometer to start your measurement. Start with the numbers, then add the tick marks. For example, if you see a “1” and one visible tick mark on the sleeve, read that as 0.1 plus 0.025, or 0.125 inches. Notice how these ticks are perpendicular to a horizontal line that goes to the thimble. Read the tick mark on the sleeve immediately below that line. If that tick mark represents 24, add 0.024 inches to the result you got from the sleeve to get 0.149 inches.
- 3). Read a vernier micrometer using the same concept that you use reading the sleeve and the thimble. If your micrometer has a vernier ruler, look for the line of the number that almost perfectly lines up with one of the numbers on the sleeve. Count each of these ticks as 0.0001 inches. Use the example in Step 2, only this time with a vernier ruler. Imagine that number 9 on the vernier ruler is almost perfectly lined up with the tick mark on the sleeve. Since each tick on the vernier ruler is 0.0001 inches apart, read that as 0.0009 inches, and add it to the result from Step 2: 0.149 + 0.0009 = 0.1499 inches.
- 4). Practice reading micrometers on websites that offer micrometer reading exercises. After you get proficient with those exercises, practice with a real micrometer (see Resources below).
