How to Read a Standard Ruler

Standard rulers contain inches subdivided into smaller fractions.

A standard ruler contains measurement increments in the English system of inches. Most standard rulers measure to the 1/8-inch or the 1/16-inch with smaller lines occurring evenly between each inch mark. A basic understanding of fractions will help you read a standard ruler accurately. Once you know the premise, you can use the ruler to measure short distances and small objects less than 12 inches long.

Things You'll Need

• Standard ruler

Instructions

1. Examine the ruler to determine what the lines along the edge mean. You will find large lines at every inch mark along one or both long edges of the ruler. Each large line will have a number, labeling the inches between one and 12 along the ruler. Between the inches, you'll find smaller lines. Each inch will have a slightly shorter line dividing it in half and two slightly shorter lines dividing the halves in half again -- dividing the inches into quarters.

2. Check to see how small the subdividing lines are on the ruler. If you see one line dividing the quarter inches in half, the ruler has eighth-inch marks. If you find the quarters divided into quarters, the ruler has 16th-inch marks. The 16th-inch divisions will be very small.

3. Notice where the "0" line falls on the ruler. Some rulers have this line at the exact edge of the ruler and other rulers place this line slightly to the right of the edge. The location of the "0" line is important for accurate measuring because you must place this point on the ruler at the exact edge of the item or space you're measuring.

4. Place the ruler along an item, such as a book, to practice measuring. Align the ruler with the "0" line at the exact bottom edge of the book and extend the ruler straight across the book to the top edge. Note the point where the book ends on the ruler. If the book ends between the 8-inch mark and the 9-inch mark, you know the book is 8 inches plus a fractional part.

   If you're measuring with a ruler marked to the 8th-inch, count the 8th-inch marks from the 8-inch line to the point where the book ends. If you're measuring with a 16th-inch ruler, count the 16th-inch marks. Add up the marks you counted and convert them to larger fractions, if possible. For example, if the book falls at the 8 6/8 line, this is equivalent to 8 3/4. If the book falls at the 8 10/16 line, this is equivalent to 8 5/8.

References

• Online Conversion: How Do I Read a Ruler?
• Atlantis: Units of Length

Resources

• Read this Article in Spanish