Length Conversion – Metric and Customary System, Examples

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What Is Length Conversion?

Length conversion refers to converting measurements of length or distance from one unit to another. This is typically done to express measurements in a more convenient or appropriate unit for a particular purpose or to compare lengths expressed with 2 different units. 

Example: Suppose you have two ropes, one 15 inches long and the other 2 feet long. Which rope is longer? Can you compare 15 inches with 2 feet? No! 

To compare the lengths, the two measurements must be in the same units. You must convert inches into feet or feet to inches and then compare. This is what we call a length conversion.

1 foot = 12 inches

2 feet = 24 inches > 15 inches

Thus, 2 feet > 15 inches

Length is a fundamental physical quantity, measured in units like meters, centimeters, inches, or feet, used to describe the size of an object from one end to another.

Length Conversion: Definition

Length conversion is the process of converting the length measurements from one unit to another using the correct conversion factor, simplifying the comparison lengths expressed in different units.

Length Conversion in the Metric System

Converting lengths within the metric system is straightforward as it is based on the decimal system and only involves moving a decimal point. In this system, the unit “meter” acts as the base unit of length, and we can obtain smaller or larger units by attaching various prefixes such as kilo, hecto, deka, deci, centi, and milli to it.

Let’s quickly revise these units, their abbreviations, prefixes, and corresponding powers of 10.

KilometerHectometerDecameterMeterDecimeterCentimeterMillimeter
kmhmdammdmcmmm
103102101100 = 110-110-210-3

How to Convert Lengths in the Metric System

Length measurement conversion in the metric system can be simplified using the following tricks:

Length Conversion – Metric and Customary System, Examples

Alt tag: Length conversion in the metric system

  • If you move n positions to the right from any place, you move n decimal places to the right. So multiply by 10n.

Examples:

  1. To convert meters (m) into decimeters (dm), multiply by 10. (1 m = 10 dm)
  2. To convert kilometers (km) into meters (m), multiply by 1000. (5 km = 5000 m)
  • If you move n positions to the left from any place, you move n decimal places to the left. So divide by 10n (or multiply by 10-n).

Examples:

  1. To convert meters (m) into kilometers (km), divide by 1000. (6 m = 0.006 km)
  2. To convert millimeters (mm) into centimeters (cm), divide by 10. (7 mm = 0.7 cm)

Length Conversion in the Customary System

The customary system, primarily used in the United States, employs inches, yards, miles, and feet to measure lengths or distances. This system is based on the English system of measurement (the same system from which the Imperial system is also derived.) 

While the metric system has largely replaced the Imperial system in many countries, the customary system remains prevalent in the United States.

Length conversions in the customary system:

  • 1 foot = 12 inches
  • 1 yard = 3 feet = 36 inches 
  • 1 mile = 5,280 feet 
  • 1 mile = 1,760 yards

Length Conversion Chart for the Customary System and Metric System

Here’s a length or distance conversion table for different units of length in the metric system and the customary system.

1 centimeter = 10 millimeters1 cm = 10 mm
1 decimeter = 10 centimeters1 dm = 10 cm
1 meter = 100 centimeters1 m = 100 cm
1 kilometer = 1000 meters1 km = 1000 m
1 inch = 2.54 centimeters1 in = 2.54 cm
1 foot = 12 inches1 ft = 12 in
1 yard = 3 feet = 36 inches1 yd = 3 ft = 36 in
1 mile = 1,760 yards = 5,280 feet1 mi = 1,760 yd = 5,280 ft
1 mile ≈ 1.61 kilometers1 mi ≈ 1.61 km

Length Conversion in the Imperial System

The Imperial system is based on the English units. It’s closely related to the customary system, but the two systems have many differences. 

  • Familiar units include the inch, foot, yard, and mile.
  • Units for land measurement consist of the furlong, chain, link, rod, pole, perch, and Ramsden’s chain.
  • Nautical units include the fathom, shackle, cable, and nautical mile.
  • Body measurements encompass the foot, hand, palm, nail, and finger.

Here are different Imperial units for length and their relationships:

1 nail= $2\frac{1}{4}$inches
4 inches= 1 hand
12 inches= 1 foot
3 foot= 1 yard
5.5 yards= 1 rod
6 foot= 1 fathom
22 yards= 1 chain
100 links= 1 chain
10 chains= 1 furlong
8 furlongs= 1 statute mile
6080 foot= 1 nautical mile

Length Conversion Table for the Imperial System and Metric System

Imperial UnitsMetric Units
1 nautical mile1.151 miles1852 meters
1 mile1760 yards1609 meters
1 furlong220 yards201 meters
1 rod5.50 yards5.029 meters
1 fathom6 feet1.829 meters
1 yard3 feet0.9144 meters
1 foot12 inches0.3048 meters
1 Inch0.083 foot0.0254 meters

Facts about Length Conversion

  • The width of a human hair is typically measured in micrometers, which are one-millionth of a meter! That’s super tiny!
  • Mount Everest, the tallest mountain on Earth, is approximately 8,848 meters or 29,029 feet. That’s nearly 5.5 miles high!

Conclusion

​​In this article, we learned about the fundamentals of length conversion in the metric, imperial, and customary systems. Let’s solidify our understanding by solving examples and practicing MCQs for better comprehension.

Solved Examples on Length Conversion

1. Convert 200 m to km.

Solution: 

By the length conversion formula for meters to kilometers, we have

1 km = 1000 m

1 m = $\frac{1}{1000}$ km

200 m = $\frac{200}{1000}$ = 0.2 km

2. Which is longer? 48 inches or 4 feet?

Solution: 

To compare lengths, bring both measurements in the same unit.

1 feet = 12 inches

4 feet = $12 \times 4$ inches = 48 inches

Thus, 48 inches = 4 feet

3. How many inches are there in 6 feet?

Solution: 

1 feet = 12 inches

6 feet = $6 \times 12$ = 72 inches

4. How many millimeters are there in 4 hectometers?

Solution: 

1 hectometer = 100 meter

1 meter = 1000 millimeters

To convert 1 hectometer into millimeters, you move 5 positions to the right.

So multiply by 105 = 1,00,000.

1 hectometer = 1,00,000 millimeters

4 hectometers = 4 × 1,00,000 = 4,00,000 millimeters

5. Which pencil is longer?

Length Conversion – Metric and Customary System, Examples

Alt tag: 2 pencils, one 6.5 in long and the other 17 cm long

Solution: 

Length of the yellow pencil = 6.5 in

Length of the black pencil = 17 cm

To compare lengths, they must be in the same units.

Let’s convert 6.5 inches into centimeters.

1 inch = 2.54 cm

Length of the yellow pencil = 6.5 inches = 6.5 × 2.54 cm = 16.51 cm

Here, 16.51 cm < 17 cm

Thus, the black pencil is longer.

Practice Problems on Length Conversion

Length Conversion - Metric and Customary System, Examples

Attend this quiz & Test your knowledge.

1

On converting 10 yards into feet, we get

50 feet
30 feet
1000 feet
300 feet
CorrectIncorrect
Correct answer is: 30 feet
1 yard = 3 feet
10 yards = 10 ✕ 3 feet = 30 feet
2

How many meters are there in 900 millimeters?

9 millimeter
90 millimeter
0.09 millimeter
0.9 millimeter
CorrectIncorrect
Correct answer is: 0.9 millimeter
1 meter = 1000 millimeters
1 millimeter = $\frac{1}{1000}$ millimeter
900 millimeters = $\frac{900}{1000}$ millimeter = 0.9 millimeter
3

Compare: 1 mile _____ 1 km

>
=
CorrectIncorrect
Correct answer is: >
1 mile ≈ 1.61 km
Thus, 1 mile > 1 km

Frequently Asked Questions about Length Conversion

A micrometer, also known as a micron, is a unit of length equal to one millionth of a meter (1 × 10-6 meters). It is commonly used to measure very small distances, such as the width of a human hair or the size of microorganisms.

A nanometer is an even smaller unit of length, equal to one billionth of a meter (1 × 10-9 meters). It is used to measure atomic and molecular scales and the dimensions of nanoscale structures in fields like nanotechnology.

1 megameter = 1,000 kilometers

1 gigameter = 1,000,000 kilometers

To convert miles into kilometers, you can use the conversion factor that 1 mile is approximately equal to 1.60934 kilometers. So, to convert miles into kilometers, you multiply the number of miles by 1.60934. Conversely, you divide the kilometers by 1.60934 to convert kilometers into miles.