# Metric Units Of Length Convert Mm, Cm, M And Km

The metric system is used by scientists, many military units, and all industrialized nations outside the U.S. As a result, this system is important to learn in order to develop your career and travel.

## Metric Units of Length | Convert mm, cm, m and km

These are the four metric units that are commonly used to measure length. There are many more units that are much shorter than millimeters and much longer than kilometers. Each unit is based on the meter. Its length is some multiple of 10 times the length of a meter.

Other metric units include the newton (a unit of force), the pascal (a unit of pressure), the watt (a unit of power), the joule (a unit of energy), and the ampere (a unit of electric current).

To convert among any units in the left column, say from A to B, you can multiply by the factor for A to convert A into m then divide by the factor for B to convert out of m. Or, you can find the single factor you need by dividing the A factor by the B factor.

The metric system is the system of measurement that uses units like meter, liter, and grams to measure the length, capacity, weight, and mass of objects."}},"@type":"Question","name":"What are metric units?","acceptedAnswer":"@type":"Answer","text":"The units of measurement in the metric system are called metric units or SI units (International System of Units). The units include meter, kilogram, gram, and so on.\u00a0","@type":"Question","name":"What unit should be used to measure the distance between 2 towns?","acceptedAnswer":"@type":"Answer","text":"We learnt that larger distances are measured in kilometers. So, the distance between 2 towns must be measured in kilometers. ","@type":"Question","name":"What unit is used to measure the length of a pencil?","acceptedAnswer":"@type":"Answer","text":"We also learnt that smaller distances or lengths are measured in centimeters and millimeters. So, the length of a pencil is measured in centimeters or millimeters.","@type":"Question","name":"Which operations are performed to convert smaller units to larger units?","acceptedAnswer":"@type":"Answer","text":"To convert a smaller unit to a larger unit, we need to divide the unit by a suitable numerical value.\u00a0"]} Check out our other courses CodingGrades 1 - 12Explore MusicAll agesExplore CodingGrades 1 - 12

In 1958, a conference of English-speaking nations agreed to unify their standards of length and mass, and define them in terms of metric measures. The American yard was shortened and the imperial yard was lengthened as a result. The new conversion factors were announced in 1959 in Federal Register Notice 59-5442 (June 30, 1959), which states the definition of a standard inch: The value for the inch, derived from the value of the Yard effective July 1, 1959, is exactly equivalent to 25.4 mm.

The current definition was adopted in 1983 and modified slightly in 2002 to clarify that the metre is a measure of proper length. From 1983 until 2019, the metre was formally defined as the length of the path travelled by light in a vacuum in .mw-parser-output .sfracwhite-space:nowrap.mw-parser-output .sfrac.tion,.mw-parser-output .sfrac .tiondisplay:inline-block;vertical-align:-0.5em;font-size:85%;text-align:center.mw-parser-output .sfrac .num,.mw-parser-output .sfrac .dendisplay:block;line-height:1em;margin:0 0.1em.mw-parser-output .sfrac .denborder-top:1px solid.mw-parser-output .sr-onlyborder:0;clip:rect(0,0,0,0);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px1/299792458 of a second. After the 2019 redefinition of the SI base units, this definition was rephrased to include the definition of a second in terms of the caesium frequency Î”Î½Cs.

Metre is the standard spelling of the metric unit for length in nearly all English-speaking nations but not the United States[2][3][4][5] or the Philippines,[6] which use meter. Other West Germanic languages, such as German and Dutch, and North Germanic languages, such as Danish, Norwegian, and Swedish,[7] likewise spell the word Meter or meter.

Since 1830, Hassler was also head of the Bureau of Weights and Measures which became a part of the Coast Survey. He compared various units of length used in the United States at that time and measured coefficients of expansion to assess temperature effects on the measurements.[55]

Regarding the precision of the conversion from the toise to the metre, both units of measurement were then defined by primary standards, and unique artifacts made of different alloys with distinct coefficients of expansion were the legal basis of units of length. A wrought iron ruler, the Toise of Peru, also called Toise de l'AcadÃ©mie, was the French primary standard of the toise, and the metre was officially defined by the MÃ¨tre des Archives made of platinum. Besides the latter, another platinum and twelve iron standards of the metre were made in 1799.[59][54][49][60][61]

In the 1870s and in light of modern precision, a series of international conferences was held to devise new metric standards. When a conflict broke out regarding the presence of impurities in the metre-alloy of 1874, a member of the Preparatory Committee since 1870 and Spanish representative at the Paris Conference in 1875, Carlos IbÃ¡Ã±ez e IbÃ¡Ã±ez de Ibero intervened with the French Academy of Sciences to rally France to the project to create an International Bureau of Weights and Measures equipped with the scientific means necessary to redefine the units of the metric system according to the progress of sciences.[89][90][49][91]

Practical realisation of the metre is subject to uncertainties in characterising the medium, to various uncertainties of interferometry, and to uncertainties in measuring the frequency of the source.[111] A commonly used medium is air, and the National Institute of Standards and Technology (NIST) has set up an online calculator to convert wavelengths in vacuum to wavelengths in air.[112] As described by NIST, in air, the uncertainties in characterising the medium are dominated by errors in measuring temperature and pressure. Errors in the theoretical formulas used are secondary.[113]

The metre is defined as the path length travelled by light in a given time, and practical laboratory length measurements in metres are determined by counting the number of wavelengths of laser light of one of the standard types that fit into the length,[117] and converting the selected unit of wavelength to metres. Three major factors limit the accuracy attainable with laser interferometers for a length measurement:[111][118]

which converts the unit of wavelength Î» to metres using c, the speed of light in vacuum in m/s. Here n is the refractive index of the medium in which the measurement is made, and f is the measured frequency of the source. Although conversion from wavelengths to metres introduces an additional error in the overall length due to measurement error in determining the refractive index and the frequency, the measurement of frequency is one of the most accurate measurements available.[118]

Conversions between measuring units are studied all through elementary school. Starting typically in grade 2 or 3, children practice easy conversions, such as changing a bigger unit into smaller units (4 cm into 40 mm) and the other way around (300 cm = 3 m). Later on they learn how to use decimal numbers in the conversions. Since the metric system is based on number 10, conversions between the units are very easy: they only involve multiplying and dividing by 10, 100, 1000, etc.

The conversions in the worksheet below are easy, as they only involve converting a larger unit into smaller units (such as 3 m = _____ cm) or writing a multiple of ten of the smaller unit in terms of the larger unit (such as 50 mm = ___ cm).

Use the generator to make customized worksheets for conversions between measuring units. You can choose to include inches, feet, yards, miles, ounces, cups, pints, quarts, gallons, ounces, pounds, millimeters, centimeters, meters, kilometers, grams, kilograms, liters, and milliliters. You can also make worksheets for the metric system: units with the prefixes milli, centi, deci, deka, hecto, and kilo.

Font: Arial Courier Courier New Helvetica sans-serif Times New Roman Verdana Font Size: 8pt 9pt 10pt 11pt 12pt 13pt 14pt 16pt 18pt 24ptCell Padding: Border: Extra vertical space below the problems: linesAdditional title & instructions (HTML allowed) Key to Measurements WorkbooksKey to Measurement workbooks include a variety of hands-on experiences related to the customary units of measurement. Group projects are included in addition to numerous individual activities. In Book 1, students learn how a linear measurement system is developed and then do activities related to measuring length. Book 2 focuses on length, perimeter, and area measures. In Book 3, the concept of area is further developed, and students are introduced to volume. Book 4 covers a variety of topics. Students experiment with weighing objects and measuring capacity, and they also learn about temperature and time.

History/origin: A centimeter is based on the SI unit meter, and as the prefix "centi" indicates, is equal to one hundredth of a meter. Metric prefixes range from factors of 10-18 to 1018 based on a decimal system, with the base (in this case the meter) having no prefix and having a factor of 1. Learning some of the more commonly used metric prefixes, such as kilo-, mega-, giga-, tera-, centi-, milli-, micro-, and nano-, can be helpful for quickly navigating metric units.

History/origin: The milli- prefix is one of many metric prefixes. It indicates one thousandth of the base unit, in this case the meter. The definition of the meter has changed over time, the current definition being based on the distance traveled by the speed of light in a given amount of time. The relationship between the meter and the millimeter is constant however. Prior to this definition, the meter was based on the length of a prototype meter bar. In 2019, the meter has been re-defined based on the changes made to the definition of a second. 041b061a72