Imperial System – Definitions, Unit Conversions, & Examples

What Is the Imperial System?

The imperial measurement system, or the British Imperial system, is a traditional system of measurements based on the old English units.

(The English units, consisting of Winchester units and Exchequer Standards, were the prevailing system before 1826. This system was subsequently replaced by the Imperial and US customary systems that were developed later.)

The imperial system of units was first defined in the British Weights and Measures Act 1824 and developed through various Acts and amendments. It replaced the Winchester Standards that had been in practice since 1588 and became official in 1826. Although most nations adopted the metric system by the late 20th century, some parts of the world still use imperial units.

Other Systems of Measurement

• The United States uses the system with the Customary units of measurement, which also originated from the old English system. Thus, the customary and Imperial systems are quite similar, with distinct differences in terms of some conversion factors and interpretations of units.
• The metric system is the measurement system that is used worldwide. The SI system (The International System of Units), commonly known as the modern form of the metric system, is the international standard for measurement. It is closely related to the metric system and is constantly updated to make it the global standard.

What Are the Different Units of Measurement in the Imperial System?

The different units of measurement in the Imperial system are known as Imperial units. The following Imperial system chart includes a list of Imperial units of measurement.

Length	Weight	Volume (liquid and dry)	Area	Volume
Mile Furlongs Chains Yards Feet Inches Hand Rod Fathom Cable Nautical mile	Grains Ounces Pounds Ton Dram Stone weight Hundred weight	Gill Quart Pint Cup Fluid ounces Fluid dram Gallon Bushel Pick Minim	Square inches Square foot Square yards Square mile Square rod Acre	Cubic inches Cubic foot Cubic yards Cubic mile Cubic rod Acre-foot Board-foot Cord

Conversion Between Imperial Units

Length	Weight	Volume	Area
1 foot = 12 inches 1 yard = 3 feet 1 mile = 1,760 yards	1 pound = 16 ounces 1 ton = 2,000 pounds	1 cup = 10 fluid ounces 1 pint = 20 fluid ounces 1 pint = 2 cups 1 quart = 2 pints 1 gallon = 4 quarts	1 square foot = 144 square inches 1 square yard = 9 square feet 1 acre = 4,840 square yards

Imperial System and Customary System

Imperial System	Customary System
It was implemented in the United Kingdom, its territories, and former colonies. It’s still prevalent in everyday use.	It is used in the United States of America.
1 Imperial fluid ounce ≈ 28.4131 milliliters	1 US fluid ounce ≈ 29.5735 ml
1 Imperial pint = 568.261 milliliters = 20 imperial fluid ounces	1 US pint = 473.176 ml = 16 US fluid ounces
1 Imperial quart = 1.13 liters = 40 fluid ounces	1 US quart = 0.94 l = 32 US fluid ounces
1 Imperial gallon = 4.54 liters = 160 fluid ounces	1 US gallon = 3.78 liters = 128 fluid ounces

Metric Units of Measurement?

The metric system is a decimal-based system of measurement. It is used worldwide in scientific calculations and research. The base units for length, weight (mass), and capacity (volume) in the metric system are meter, gram, and liter, respectively.

Different units in the metric system are:

• Length: Meter (m), Kilometer (km), Hectometer (hm), Decameter (dam), Decimeter (dm), Centimeter (cm), Millimeter (mm), etc.
• Weight: Gram (g), Kilogram (kg), Milligram (mg), etc.
• Capacity: Milliliter (mL or ml), Liter (L or l), etc.

Is the Imperial System Still in Use?

• In the United Kingdom, metric units are officially used, but Imperial units are still found in everyday transactions among the general population.
• The United States, the customary system or the US standard system is officially used (which is similar to the Imperial system except for the volume measurements). Despite initial intentions to adopt the metric system, the United States continues to use the Imperial system. 
• In many parts of the government in Libya and Myanmar, the Imperial system is prevalent. In contrast, other parts have started using the SI system.

Easy Conversions Between Imperial and Metric Units

The table shows the different conversions between metric and imperial units.

Length	Mass	Volume/Capacity
1 in = 2.54 cm 1 ft = 30.48 cm 1 yard = 91.44 cm 1 yard = 0.9144 m 1 mile = 1609.34 m 1 mile = 1.6 km	1 oz = 28.34952 grams 1 lb = 0.45359 kg 1 lb = 453.59237 grams 1 imperial ton = 1.01605 tonnes 1 imperial ton = 2240 pound	1 gallon = 4.54609 liters 1 fl oz = 28.4131 ml 1 cup = 284.131 ml 1 pint = 568.261 ml 1 quart = 1.1365 liters

Facts about Imperial System

Conclusion

In this article, we have learned about the imperial system and the conversions between imperial and metric systems. Now, let’s solve some examples and practice problems to understand the conversions better. 

Solved Examples on Imperial System

Example 1: Change the following lengths into inches.

i) 4 feet

ii) 7 yards

iii) 3 miles

Solution: 

i) 4 feet

1 foot = 12 inches

Thus, 4 feet = 4 × 12 = 48 inches

ii) 7 yards 

1 yard = 3 ft = 36 inches

7 yards = 7 × 36 inches = 252 inches

iii) 3 miles

1 mile = 1760 yards = 1760 × 36 inches = 63,360 inches

Thus, 3 miles = 63,360 × 3 inches = 190,080 inches

Example 2: Convert the following length measurements into centimeters.

i) 6 inches

ii) 8 feet

iii) 4 yards

Solution: 

i) 6 inches:

1 inch = 2.5 cm

Thus, 6 inches = 6 × 2.5 cm = 15 cm

ii) 8 feet

1 foot = 12 inches. 

Thus, 8 feet = 8 × 12 inches = 96 inches

Now, 1 inch = 2.5 cm

Thus, 96 inches = 96 × 2.5 cm = 240 cm

iii) 4 yards:

1 yard = 3 feet

Thus, 4 yards = 4 × 3 feet = 12 feet

1 foot = 12 inches

Thus, 12 feet = 12 × 12 inches = 144 inches

Now, 1 inch = 2.5 cm

Thus, 144 inches = 144 × 2.5 cm = 360 inches

Example 3: Convert 5 imperial gallons into liters.

Solution:

1 imperial gallon = 4.54609 liters

5 imperial gallons = 5 × 4.54609 liters 

5 imperial gallons = 22.7304 liters

Practice Problems on Imperial System

Frequently Asked Questions about Imperial System