Finding the percent of length in inches requires obtaining two measurements. For example, you can measure the length of an object within a room and the total length of the room in inches to find the percentage of the room that the object takes up. Or, you can calculate the percent change of length in inches by calculating the percentage difference between the old and new length. This assists in determining periodic growth or shrinkage of an object. Knowledge of basic mathematics is required to perform these calculations, including addition, subtraction, division, fractions and decimals.

### Percent of Length

Measure the total length of a particular space or object in inches. Write this number as the denominator (bottom digit) of your fraction.

Measure part of the length of that same space or object in inches. Write this number down as the numerator (top digit) of a fraction.

Divide the numerator by the denominator to find a decimal representation of the length.

Move the decimal over two places to the right to find the percent of length in inches that the object or part of space takes up within the total amount.

### Length Percent Change

Measure the length of an object in inches. Write the length down as the original length.

Measure the length of the same object after its undergone some change. Write the new length down.

Subtract the old length in inches from the new length in inches. Write the difference (change of length) as the numerator of your fraction. Write the old length as the denominator of your fraction.

Divide the numerator by the denominator to find a decimal. Move the decimal two places to the right to find the percent change from the original measurement to the current measurement to record growth or shrinkage percentage.