Length Conversion
Length conversion is the process of converting lengths from one unit to another. For example, kilometers can be converted to meters, miles can be converted to yards, yards can be converted to inches, and so on. Length conversion is needed for matching measurements across different scales.
When we look around us, we come across various length values. We have the length of a freeway, which is in miles, or the length of a pencil which is calculated in inches. In this lesson, we will see the basics of length conversion, the length conversion table, and the length conversion formula.
1.  Define Length Conversion 
2.  Length Conversion in Metric Measurement System 
3.  Length Conversion in Imperial Measurement System 
4.  What is the Length Conversion Table? 
5.  FAQs 
Define Length Conversion
Length conversion is the procedure of converting the units of length with the help of the correct conversion factor. We deal with measurements every day and converting these units to the required unit involves the process of multiplication or division.
For example, the height of a table is measured in inches, the length of a book is measured in centimeters, and we measure our height in feet. All these units can be converted into another unit by performing fixed conversion operations. When we convert the length from one unit to another it is called length conversion.
Length Conversion in Metric Measurement System
The metric system is a system of measurement which is used throughout the world by scientists and mathematicians. The system is based on multiplication and division by 10. There are seven frequently used units when we consider measurement. When it comes to length conversion, 1 meter is the base unit while carrying out the metric conversion. Let us see the steps given below which are used in length conversion.
The following table shows the conversion of meters into different units of a meter.
Base Unit  Other Metric Units 
1 meter  1/1000 kilometer 
1 meter  1/100 hectometer 
1 meter  1/10 decameter 
1 meter  10 decimeter 
1 meter  100 centimeter 
1 meter  1000 millimeter 
Length Conversion in Imperial Measurement System
The imperial system of units is the system which was first defined by the British, to measure different quantities. The Weights and Measures Act of 1824 and the Act of 1878 established the British Imperial System on the basis of precise definitions of selected existing units. Let us see the length conversion table for the imperial measurement system of length.
1 nautical mile  1.151 miles  1852 meters 
1 mile  1760 yards  1609 meters 
1 furlong  220 yards 
201 meters 
1 rod  5.50 yards  5.029 meters 
1 fathom  6 feet  1.829 meters 
1 yard  3 feet  0.9144 meters 
1 foot  12 inches  0.3048 meters 
1 Inch  0.083 foot  0.0254 meters 
What is the Length Conversion Table?
A length conversion table is an arrangement where length measurement units are converted to other units. It lists the conversion factors between each unit of length. The following table consists of a few common units from the Metric system of measurement as well as the Imperial system of measurement. The table can be used directly to convert units without using any calculators.
1(mm)  1(m)  1(in)  1(ft)  1(mi)  
1 millimeter(mm)  1  0.001  0.0393  0.0032  0.00000062 
1 meter(m)  1000  1  39.37  3.28  0.00062 
1 inch (in)  25.4  0.0254  1  0.0833  0.000015 
1 foot(ft)  304.8  0.304  12  1  0.000189 
1 mile(mi)  1609344  1609.344  63360  5280  1 
Now, let us look at the following tips used in length conversion.
 It is important to convert all the different units of length into one common unit before solving the questions.
 The conversion among the metric system can be done by multiplying or dividing by 10 or the multiples of 10.
 Meter is also called the SI unit of length or base unit of length.
 The USA follows the Metric system as well as the Imperial system of conversion.
Solved Examples on Length Conversion

Example 1: How many miles are there in 20,000 meters?
Solution: As per the metric conversion chart, 1 mile is equal to 1609 meters. It is given that we need to convert 20,000 meters to miles. So, we need to divide 20,000 meters by 1609, to get the answer in miles. Hence, 20,000/1609 = 12.43 miles.

Example 2: Steve built a rectangular playboard with a length of 50 cm and an area of 2 m², find the breadth of the playboard.
Solution:
The area of the playboard = 2 m², and the length of the playboard = 50 cm. In any length conversion question, we convert all the quantities of length into one common unit. 50 cms = 50/100 = 0.5 m. The formula for area is equal to the product of length and breadth. Area = length × breadth. 2 = 0.5 × breadth. Breadth = 2/0.5 = 20/5 = 4. Therefore, the breadth of the rectangle is 4 m.

Example 3: Rony is running in an interschool onemilelong race. If he runs at a speed of 5 m/s how much time will he take to complete the race?
Solution:
The speed of Rony is 5 m/sec. The distance he has to cover is 1 mile. The formula for Time is Distance ÷ Speed. We need to convert miles to meters so that both the values are in the same unit. 1 mile is equal to 1609 meters. So, the time taken = 1609 m ÷ 5 m/sec = 1609/5 = 321.8 seconds. Therefore, Rony will take 321.8 seconds to complete the race.
Practice Questions on Length Conversion
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FAQs on Length Conversion
How Many Lengths are in a Meter?
Meter can be converted to many other units. Some of them are centimeters and millimeters. One meter consists of 100 cm and there are 1000 millimeters in a meter.
What is the Smallest Unit of Length?
The smallest unit of length is 'Planck's Length' which is nearly equal to 1.6 × 10^{35} meters.
What is the Largest Unit of Length?
Parsec is the largest unit of length. It is used to measure space distances. 1 Parsec = 3.09 × 10^{16} meters.
How do you Calculate Length in Inches?
To calculate length in inches we need the conversion factor related to the two given units of length. For example, 1 foot is equal to 12 inches, so to convert 5 feet to inches, we multiply 5 by the conversion factor 12 to get the answer in inches. 5 × 12 = 60 inches. Similarly, any length expressed in any unit can be expressed in inches by using the correct conversion factor.
How do you Calculate Length?
To calculate the length we need to define two important characteristics. First, we need to identify the start point and the end point. Secondly, we need to identify the unit of measuring the length. If the length is across two points on a sheet of paper we may take the unit of centimeters or inches. In case we need to measure the length or distance between two cities, we use the unit of kilometer or mile.
What are the Different Measurements of Length?
The different measurements of length are the SI units or the US Customary units. In the SI units, we use a standard unit of meter and in the US units, we use feet as a standard unit of measurement.
How to do Length Conversions?
Length conversions are done with the help of the correct conversion factor. First of all, the relationship between the two units is seen and accordingly the unit is multiplied or divided by the appropriate conversion factor. The following table lists a few conversion units which help to convert lengths from one unit to another.
1 nautical mile  1.151 miles  1852 meters 
1 mile  1760 yards  1609 meters 
1 yard  3 feet  0.9144 meters 
1 foot  12 inches  0.3048 meters 
1 Inch  0.083 foot  0.0254 meters 
What Are the Main Units of Length in the US?
The main units of length in the US are feet, yards, inches. Further, these US units can be converted to the other systems of measurement such as the International System of Units(SI) or the British Imperial System.