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Units of Measurement
The units of measurement are the units that are used to represent physical quantities like length, mass, temperature, current, area, volume, intensity, etc. We use different measurement units to represent the magnitude of the physical quantities including the traditional units, the Metric System of units, the imperial system of units, and US customary units. Units of measurement have also evolved and played a crucial role from the early ages till the present. We use the measuring units to compare how large or small a physical quantity is as compared to the basic standard quantity.
In this article, we shall explore the concept of metric and imperial units of measurement. We will also discuss the various measurement units used for measuring length, mass, time, temperature, and volume. Generally, we measure almost everything around us in our daily lives such as how many hours we have worked and slept, the amount of water we drink, our body weight, height, distance traveled on foot and by car. We shall solve various examples using the different units of measurement for a better understanding of the concept.
What are Units of Measurement?
The units of measurement are the collection of standard and other units that are used to measure various physical quantities. We have been using different units to measure these quantities like length, mass, volume, current, temperature, etc. from the early ages. These units of measurement have evolved since then and we have different systems of measurement now which are more convenient and easy to use.
In the early days, when we didn't have any proper tools to measure the physical quantities, we use some informal methods and units of measurement. For example, we used the body parts to measure the length such as hand span, foot span, arm span, cubit, pace, etc. Since the body parts vary from person to person, these methods of measurement did not give very accurate results. So, gradually better units of measurement were invented.
As a result, the metric system, also known as the International System of Units (called the SI units  the modern form of the metric system), the Imperial system, and US customary units were standardized across the world as the units of measurement to get more accurate results.
Metric Units of Measurement
The metric units of measurement in mathematics are standard units defined to measure length, height, weight, area, and capacity (volume). It is based on the decimal system as it includes numbers in powers of 10. The modern form of the metric units are called the SI units and are accepted worldwide. Each unit has a universally recognized size. Let us see some of the commonly used SI units in the table below.
SI Units of Measurement
SI units of measurement are units of the international system of units, also known as the metric system which is used across the world and each unit has a standard measure.
Physical Quantity  SI Unit of Measurement  Symbol 

Length  Meter  m 
Mass  Kilogram  kg 
Temperature  Kelvin  K 
Time  Second  s 
Capacity/Volume  Litre  L 
Current  Ampere  A 
Amount of Substance  Mole  mol 
Unit of Measurement List
The table above shows the SI units but we use other units as well to measure the given physical quantities. Let us list some of the commonly used to units of measurement below:
 Length  kilometer, meter, centimeter, millimeter
 Mass  kilogram, gram, milligram
 Capacity  kilolitre, litre, milliliter, centilitre
 Time  Minute, Hour, Second, Days, Week, Month, Year
 Temperature  Kelvin, Celsius, Fahrenheit
All the above units for a specific physical quantity can be expressed in terms of each other using the conversion of the units of measurement.
Imperial Units of Measurement
Imperial units of measurement are the units from the British Imperial System (System of Weights and Measures used in Great Britain). As we discussed the metric units, the imperial system uses different units to measure the physical quantities like length, mass, volume, and area. Let us go through imperial units of measurement in the table below:
Physical Quantity  Imperial Units 

Length  foot, inch, yard, mile 
Mass  ounce, pound, stone, ton 
Capacity  gallon, pint, quart, fluid ounce 
Note: The imperial units of measurement can be expressed in terms of the metric units and viceversa as they are standard units.
Units of Measurement for Length
Length is a physical quantity that gives the measure of how long an object is. There are different aspects of measuring length such as distance covered, height, etc. Units of measurement for all the physical quantities belong to the same category. Each unit of measuring length can be expressed in terms of each other using the conversion method as these units have a standard value. Let us see the commonly used metric and imperial units of measurement of length below along with their relations with one another.
System  Units of Measurement  Conversion 

Metric Units  Centimeter (cm)  1 cm = 10 mm 
Meter (m)  1 m = 100 cm  
Kilometer (km)  1 km = 1000 m  
Millimeter (mm)  1 mm = 0.001 m  
Imperial Units  Foot (feet)  1 foot = 12 inch 
Inches (inch)  1 inch = 0.83333 feet  
Mile  1 mile = 5280 feet  
Yard  1 yard = 3 feet = 36 inch 
Units of Measurement for Mass
Mass is a physical quantity that tells how heavy or light an object is. It is also commonly called the weight of the object. The SI unit of mass is the kilogram (kg). The table below shows the different and commonly used units of measuring mass in the metric and imperial systems along with their conversions:
System  Units of Measurement  Conversion 

Metric Units  Milligram (mg)  1 mg = 0.001 g 
Gram (g)  1 g = 1000 mg  
Kilogram (kg)  1 kg = 1000 g  
Imperial Units  Ounce (oz)  1 oz = 0.0625 lb 
Pound (lb)  1lb = 16 oz  
Ton  1 ton = 2000 lbs 
Please note that there are other units of measurement of mass that are used such as tonnes, stone, microgram imperial ton, etc. The above table shows the commonly used units only.
Units of Measurement for Volume
Volume, also known as the capacity, gives the amount of space that an object occupies or the maximum space the object has. The SI unit of volume is litre (L). We can also express the units of measuring volume in terms of cubic length units such as centimeter cube (cm^{3}), meter cube (m^{3}), etc. Let us go through some of the commonly used units of measurement of volume in the table below:
System  Units of Measurement  Conversion 

Metric Units  Millilitre (ml)  1 m = 0.001 l 
Litre (l)  1 l = 1000 ml  
Kilolitre (kl)  1 kl = 1000 l  
Cubic Centimeter (cm^{3})  1 l = 1000 cm^{3}  
Imperial Units  Fluid ounce (fl. oz.)  1 fl. oz. = 1/20 pt 
Gallon (gal)  1gal = 128 fl. oz.  
Pint (pt)  1 pt = 16 fl. oz. 
Units of Measurement for Temperature
Temperature is a physical quantity that describes how hot or cold an object or the weather is. We have mainly three units of measurement of temperature, Celsius, Kelvin, and Fahrenheit. Kelvin is the SI unit of measuring temperature. The table given below shows the different units of measuring temperature and their conversion.
Units of Measurement  Conversion 

Celsius (C)  0°C = 273.15 K = 32°F 
Kelvin (K)  0 K = 273. 15°C = 459.57 °F 
Fahrenheit (F)  0°F = 17.778°C = 255.372 K 
Generally, for the conversion of temperature, we use the formula C/5 = (F  32) / 9 = (K  273.15) / 5. This formula helps to express the temperature in different units.
Units of Measurement of Time
Time is a measure that tells about the time taken to complete a process, travel from one point to another. It is an ongoing process of continuous events. We measure time in three units, seconds, minutes, hours, days, weeks, months, and years. The table given below describes these units and their relation with each other.
Units of Measurement  Conversion 

Second (s)  1 s = 1/60 min 
Minute (min)  1 min = 60 s 
Hour (hr)  1 hr = 60 min = 3600 s 
Day  1 day = 24 hr 
Week  1 week = 7 days 
Month  1 month = 4 weeks 
Year  1 year = 12 months 
These units of measurement of time are standard and are followed all across the world.
Units of Measurement Chart
Now that we have discussed the different units of measurement used across different systems of measurement, let us summarize the units in a chart below for a quick review:
Quantity  Units of Measurement 

Length  Meter, Kilometer, Centimeter, Millimeter, Feet, Yard, Inch, Mile 
Mass  Gram, Milligram, Kilogram, Ounce, Pound, Ton 
Volume  Litre, Millilitre, Kilolitre, Gallon, Pint, Fluid Ounce 
Time  Second, Minute, Hour, Day, Month, Week, Year 
Temperature  Kelvin, Celsius, Fahrenheit, 
Important Notes on Units of Measurement
 The units of measurement are the units that are used to represent physical quantities like length, mass, temperature, current, area, volume, intensity, etc.
 We use two systems of units of measurement  metric and imperial.
 In the early days, hand span, arm span, and foot span were used as units of measurement.
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Units of Measurement Examples

Example 1: What is the unit 'acre' used for? Express one acre in terms of sq. yards and sq. feet.
Solution: An acre is a unit of measurement of area. Earlier, it was used to measure the size of the field. One acre is equal to 43,560 square feet. We can also express acre in terms of square yards.
1 acre = 43,560 square feet = 4840 square yards.
Answer: 1 acre = 43,560 square feet = 4840 square yards.

Example 2: Convert 5 kilograms in an imperial unit of measurement pound.
Solution: We know that 1 kilogram is approximately equal to 2.2 pounds. So, 5 kg in pounds is given by,
5 kg = 5 × 2.2 pounds
= 11 pounds
Answer:5kg is equal to 11 pounds.

Example 3: How many feet are there in 3 miles?
Solution: We know that 1 mile is equal to 5280 feet. So, 3 miles in feet are given by,
3 miles = 3 × 5280 feet
= 15,840 feet
Answer: 3 miles is equal to 15, 840 feet.
FAQs on Units of Measurement
What are the Units of Measurement in Math?
The units of measurement are the units that are used to represent physical quantities like length, mass, temperature, current, area, volume, intensity, etc. We use different measurement units to represent the magnitude of the physical quantities including the traditional units, the Metric System of units, the imperial system of units, and US customary units.
What are the 7 Basic Units of Measurement?
The 7 basic units of measurement are:
 Length  Meter (m)
 Mass  Kilogram (kg)
 Capacity  Litre (L)
 Electric Current  Ampere (A)
 Amount of Substance  Mole (mol)
 Luminous Intensity  Candela (cd)
 Temperature  Kelvin (K)
What are the Units of Measurement in the Metric System?
The standard units of measurement for specific physical quantities used in the metric system are:
 Length  Meter
 Mass  Kilogram
 Volume  Litre
How to Convert Units of Measurement of Temperature?
We can convert the units of measurement of temperature using the formula C/5 = (F  32) / 9 = (K  273.15) / 5, where C  Celsius, F  Fahrenheit, K  Kelvin
What are the 3 Systems of Units of Measurement?
The 3 systems of units of measurement are Metric System, Imperial System, and the US customary system.
What are Units of Measurement Used for?
We use different measurement units to represent the magnitude of the physical quantities including the traditional units, the Metric System of units, the imperial system of units, and US customary units.
Why are Standard Units of Measurement Needed?
In the early days, people used body parts to measure the length such as hand span, foot span, arm span, cubit, pace, etc. Since the body parts vary from person to person, these methods of measurement did not give very accurate results. So, standard units of measurement were invented.
What are the Different Units of Measurement for Length?
The commonly used units of measurement for length are meter, centimeter, kilometer, millimeter, decimeter, decameter, etc.
What are Imperial Units of Measurement?
Imperial units of measurement are the units from the British Imperial System (System of Weights and Measures used in Great Britain). These units are used to measure length, volume, mass, area, etc.
What are Metric Units of Measurement?
The metric units of measurement in mathematics are standard units defined to measure length, height, weight, area, and capacity (volume). The modern form of the metric units are called the SI units and are accepted worldwide.
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