The way base units of length have been determined has changed greatly over time. Long ago, the base for reference was the human body. For example, the cubit was a unit that indicated the length from the elbow to the fingertips. Gradually the units of measurement were standardized and different systems of measurement evolved.

Currently, the most commonly used system is the metric system of measurement among the 3 systems of measurement.

## What is a System of Measurement?

Measurement systems are a collection of units of measurement and rules relating them to each other. The word “measurement” is derived from the Greek word “metron,” which means a limited proportion. This word also finds its roots in the words “moon” and “month”, possibly because astronomical objects were among the first methods to measure time.

## The 3 Systems of Measurement

The 3 systems of measurement are

- Metric System of Measurement
- US Standard System of Measurement
- British Imperial System

### Metric System of Measurement

A system of measurement in which the basic units are the meter, the second, and the kilogram. In this system, the ratios between units of measurement are multiples of ten. For example, a kilogram is a thousand grams, and a centimeter is one-hundredth of a meter.

The units for length, weight (mass), and capacity(volume) in the metric system are:

**Length/Distance:**Millimeter (mm), Decimeter (dm), Centimeter (cm), Meter (m), and Kilometer (km) are used to measure how long or wide, or tall an object is. Examples include measuring the thickness or length of a notebook, length of cloth, or distance between two cities.**Weight/Mass:**Gram (g) and Kilogram(kg) are used to measure how heavy an object is, using instruments. Examples include measuring the weight of vegetables and fruit, and the weight of our body.**Capacity/Volume:**Milliliter (ml) and Liter (l) are used to measure how much quantity of liquid an object can hold. Examples include measuring the amount of juice in a can, or the amount of water in a water tank.

Following is the relation between the different units in the metric system of measurement.

1 centi | 10 milli |

1 deci | 10 centi |

1 unit | 10 deci |

1 deca | 10 unit |

1 hecto | 10 deca |

1 kilo | 10 hecto |

To convert from lower unit to higher, we divide, and to convert from higher unit to lower unit we multiply.

For example, 1 centimeter = 1/100 metre and 1 kilometer = 1000 metre

### US Customary System of Measurement

The customary system of measurement also called the U.S. Customary System, is based on the English system of measurement. In math, the customary system can be defined as a set of weights and measures used for measuring length, weight, capacity, and temperature. Length and distances in the customary system are measured in inches, feet, yards, and, miles.

The units for length, weight (mass), and capacity(volume) in the US customary system are:

**Length/Distance:**The U.S. customary units to measure length and distances in the customary system are inches, feet, yards, and miles.**Weight/Mass:**The U.S. customary units for measuring weight are ounces, pounds, and tons.**Capacity/Volume:**The U.S. customary capacity or volume measurement units are ounces, cups, pints, quarts, and gallons.

Following is the relation between the different units in the metric system of measurement.

**Length/Distance**

1 foot | 12 inches |

1 yard | 3 feet |

1 mile | 1760 yards |

**Weight/Mass**

1 pound | 480 ounces |

**Capacity/Volume**

1 tablespoon | 3 teaspoons |

1 fluidounce | 2 tablespoons |

1 cup | 8 fluidounces |

1 pint | 2 cups |

1 quart | 2 pints |

1 gallon | 4 quarts |

### British Imperial System

A system of measurement in use in the United Kingdom and other Commonwealth countries, now mostly superseded by the metric system; similar to the system currently used in the United States; consisting of units such as the inch, the mile, and the pound (of weight).

The units for length, weight (mass), and capacity(volume) in the US customary system are:

**Length/Distance:**Inches (in), Feet (ft), Yard (yd), Mile (mi)**Weight/Mass:**Grain (gr), Ounce (oz), Quarter (qr or qtr), Stone (st), Pound (lb), Ton (t)**Capacity/Volume:**fluid ounce (fl oz), gill (gi), pint (pt), quart (qt), gallon (gal)

**Length**

1 foot | 12 inches |

1 yard | 3 feet |

1 mile | 1760 yards |

**Weight/Mass**

1 pound | 16 ounces |

1 ton | 2000 pounds |

**Capacity/Volume**

1 cup | 8 fluidounces |

1 pint | 2 cups |

1 quart | 2 pints |

1 gallon | 4 quarts |

## Conversion Between Systems of Measurement

Following are the relation between US customary system and British imperial system with respect to metric system

**Length**

1 inch | 2.54 centimeter |

1 foot | 30.48 centimeter |

1 yard | 91.44 centimeter |

1 mile | 1.61 kilometer |

**Weight/Mass**

1 ounce | 28.35 gram |

1 pound | 453.59 gram |

1 tonne | 1000 kilogram |

**Capacity**

1 cup | 236.59 milliliter |

1 pint | 568.26 milliliter |

1 quart | 946.35 milliliter |

1 gallon | 4.55 litre |

## Conclusion

System of measurement refers to the process of associating numbers with physical quantities and phenomena. It is more like a collection of units of measurement and rules relating them to each other.