# U s to metric conversion chart: Metric Conversion charts and calculators

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## Length conversion

#### Metric measurements

Metric measurements of length are widely used around the world due to their simplicity and consistency. The base unit of length in the metric system is the meter (m), which is defined as the distance traveled by light in a vacuum in 1/299,792,458 second. This fundamental unit can be easily converted into smaller or larger units by using prefixes.

For smaller measurements, the most commonly used metric units are the centimeter (cm) and the millimeter (mm). A centimeter is equal to one-hundredth of a meter, while a millimeter is one-thousandth of a meter. These units are often used for precise measurements, such as the length of objects or the thickness of materials.

Larger measurements of length are expressed in kilometers (km) or meters (m). A kilometer is equal to one thousand meters, making it suitable for measuring longer distances, such as the length of roads or the size of countries. Meters are commonly used for everyday measurements, such as the height of a person or the width of a room.

The metric system’s decimal-based nature makes it easy to convert between different units of length by simply moving the decimal point. This simplicity, along with its widespread adoption, has made the metric system the preferred choice for scientific, industrial, and everyday measurements across the globe.

#### Imperial / American measurements

Imperial or American measurements of length are commonly used in the United States and a few other countries that have not adopted the metric system. These measurements are based on historical units that were used in the British Empire and have since been standardized.

The most commonly used unit of length in the Imperial system is the inch, which is equivalent to 2.54 centimeters. Twelve inches make up a foot, and three feet make up a yard. The yard is often used for measuring longer distances, such as in construction or landscaping.

For larger measurements, the mile is used. A mile is equal to 1,760 yards or approximately 1.6 kilometers. Miles are commonly used for measuring distances in road travel and aviation.

While the Imperial system of measurements is still widely used in the United States, many other countries have transitioned to the metric system, which is based on units of ten.

#### Meters

Meters, as a unit of measurement, are widely recognized and used for measuring length in the metric system. The meter is defined as the distance traveled by light in a vacuum in 0.000000003335641 seconds. This definition provides a precise and consistent standard for measuring length, making the meter a fundamental unit in the International System of Units (SI).

The meter is commonly used in various fields, including science, engineering, and everyday life. It provides a convenient and easily understandable way to quantify distances, whether it’s measuring the length of a room, the height of a building, or the distance between two cities. The use of meters allows for accurate and standardized measurements across different countries and disciplines, promoting consistency and facilitating international communication and trade.

The meter is part of a decimal-based system, making it easy to convert between different units of length within the metric system. For example, there are 1,000 millimeters in a meter, and 100 centimeters in a meter. This simplicity and flexibility make the meter a versatile unit of measurement, suitable for a wide range of applications. Whether it’s measuring small objects or vast distances, the meter provides a reliable and universally accepted standard for length measurement.

#### Feet

Feet, as a unit of length, is commonly used in the United States and a few other countries that have not fully adopted the metric system. One foot is equal to 12 inches or 0.3048 meters. The term «foot» is derived from the human foot, which was historically used as a reference for measuring length.

The use of feet as a unit of measurement dates back to ancient civilizations, where the length of a foot was often based on the (albeit large) size of a person’s foot. Over time, the measurement became standardized, and the foot was defined as a specific fraction of other units, such as the yard or the meter.

Feet are primarily used in everyday situations to measure shorter distances, such as the height of a person or the length of a room. They are also commonly used in construction, architecture, and engineering, where precise measurements are required. However, it is important to note that the use of feet is becoming less common in scientific and international contexts, where the metric system is widely used.

## Weight conversion calculators for imperial and metric units

#### Metric measurements

Metric measurements of weight are widely used around the world due to their simplicity and consistency. The base unit of weight in the metric system is the kilogram (kg) and not the gram (g) as often stated. A kilogram is defined as the weight of one liter of water at its maximum density.

The metric system also provides a convenient way to convert between different units of weight. For instance, to convert from grams to kilograms, one simply needs to divide the number of grams by 1000. Similarly, to convert from kilograms to grams, one multiplies the number of kilograms by 1000. This ease of conversion makes the metric system particularly useful in scientific and everyday applications, as it allows for quick and accurate calculations.science, industry, and everyday life.

In addition to grams and kilograms, the metric system also includes larger units of weight such as metric tons (t) and smaller units such as micrograms (µg). This wide range of units allows for precise measurements across a variety of contexts, from measuring the weight of a small object to the mass of a large vehicle. Overall, the metric system’s consistent and logical approach to weight measurement makes it an invaluable tool in various fields.

#### Imperial / American measurements

Imperial and American measurements of weight are commonly used in the United States and a few other countries that have not fully adopted the metric system. These systems are based on the pound as the primary unit of weight. In the Imperial system, the pound is divided into 16 ounces, while in the American system, it is divided into 16 avoirdupois ounces.

The Imperial system of weight is primarily used in the United Kingdom and some former British colonies. It is often referred to as the avoirdupois weight system. In this system, larger units of weight include the stone (equal to 14 pounds) and the hundredweight (equal to 112 pounds). The ton is also used, with the long ton equal to 2,240 pounds and the short ton equal to 2,000 pounds.

In the American system, the pound is also the most commonly used unit of weight. It is used in everyday life for measuring the weight of people, food, and objects. The ton is also used, with the short ton being the standard unit of weight in the United States. Additionally, the ounce is commonly used for measuring smaller weights, such as the weight of ingredients in recipes or the weight of mail.

#### Avoirdupois system

The Avoirdupois system of weight is a commonly used system of measurement in the United States and several other countries. It is primarily used for measuring everyday objects and commodities, such as groceries, household items, and industrial materials. The system is based on the pound as the primary unit of weight, which is further divided into ounces and then into smaller units such as drams and grains.

In the Avoirdupois system, one pound is equal to 16 ounces, and one ounce is equal to 16 drams. This system is different from the Troy system, which is used for measuring precious metals and gemstones. The Avoirdupois system is also distinct from the metric system, which is widely used in most countries around the world.

The Avoirdupois system is commonly used in trade and commerce, as well as in everyday life. It is used to measure the weight of goods, determine shipping costs, and calculate nutritional information on food packaging. While the metric system is gaining popularity globally, the Avoirdupois system remains deeply ingrained in American culture and continues to be widely used in the United States.

#### Troy system

The Troy system of weight is a historical system of measurement that is primarily used for weighing precious metals, such as gold and silver. It is named after the city of Troy in ancient Greece, where it is believed to have originated. The Troy system is different from the more commonly used avoirdupois system, which is used for everyday items and commodities.

In the Troy system, the pound is divided into 12 ounces, and each ounce is further divided into 20 pennyweights. The pennyweight is then divided into 24 grains. This system is often used in the jewelry industry, where precise measurements of precious metals are crucial. For example, a gold necklace may be described as weighing 1.5 troy ounces, or a silver ring may be sold by its weight in troy grains.

While the Troy system is not widely used in everyday life, it is still important in certain industries and for historical purposes. It is essential for those working with precious metals to understand and convert between the Troy and avoirdupois systems accurately. Online conversion tools and charts are readily available to assist in these conversions, making it easier for individuals to navigate between the two systems of weight measurement.

#### Which is heavier; a pound of feathers or a pound of gold?

The answer is a pound of feathers as feathers would be measured with avoirdupois pounds and gold would be measured with troy pounds. Since avoirdupois pounds are heavier, feathers is the answer.

## table, dimensions, conversion to metric

The table shows the outer diameters, which can be found by measuring the tap / bolt at the peak of the top.

Diameter, inch Diameter, mm Pitch, threads/inch Pitch, mm
1/8 9. 728 28 0.907
1/4 13.157 19 1.337
3/8 16.662 19 1.337
1/2 20.955 14 1.814
5/8 22.911 14 1.814
3/4 26.441 14 1.814
7/8 30.201 14 1.814
1 33.249 11 2.309
1.1/4 41.910 11 2.309
1.1/2 47.803 11 2.309
1.3/4 53.746 11 2.309
2 59.614 11 2.309
3 87.884 11 2.309

Parallel pipe thread (BSPP — British Standard Pipe Parallel) used in the plumbing industry. Heating batteries, radiators, water supply, fittings — it’s all about her.

Tooth profile — 55° , GOST 6357-81. Has only the main step.

##### What is the pipe thread diameter?

Nominal size in inches means internal pipe diameter (nominal size), which is quite logical for calculating the flow of water, but confusing when selecting a tool.

This is why a G 1 tap will thread a pipe with an outside diameter of 32 mm, because it has just 1 inch (25.4 mm) inside.

Diameter, inch Diameter, mm Pitch, threads/inch Pitch, mm
#1 1.854 64 0.397
#2 2. 184 56 0.454
#3 2.515 48 0.529
#4 2.845 40 0.635
#5 3.175 36 0.706
#6 3.505 32 0.794
#8 4.166 28 0.907
#10 4.826 24 1.058
#12 5.486 22 1.155
1/4 6.350 20 1.270
5/16 7.938 18 1.411
3/8 9.525 16 1.588
7/16 11.112 14 1.814
1/2 12.700 13 1.954
9/16 14. 288 12 2.117
5/8 15.875 11 2.309
3/4 19.050 10 2.540
7/8 22.225 9 2.822
1 25.400 8 3.175
1.1/8 28.575 7 3.629
1.1/4 31.750 6 4.233
1.3/8 34.925 5 5.080
1.1/2 38.100 4 6.350
1.3/4 44.450 3 8.467
2 50.800 2 12.700

Inch thread is also called «American», since it is in the USA that it is most common.

Tooth profile — 60° , but unlike metric, all sizes are in inches, which results in «strange» figures for Europeans.

The letter designation immediately shows which pitch the thread belongs to:

• UNEF

The same diameter can have several different pitches, for example:

• UNC 1/4×20
• UNF 1/4×28
• UNEF 1/4×32
• UNS 1/4×36

That is why it is extremely important to take into account / measure the pitch of an inch thread.

##### How to convert UNC 1/4×20 thread to mm?

See table:

1/4 = 6.35 mm
20 threads per inch = 1.27 mm
In metric format, the thread would be designated as follows: M6.35×1.27

Another example, UNEF 5/8×24 fine thread:

5/8 = 15. 875 mm
24 threads per inch = 1.058 mm
Total approximately analogue of M16x1.

In practice, these inch thread designations are used in the opposite direction — first, an unknown thread is measured with a caliper / thread gauge, after which its parameters are determined by selection in order to purchase the necessary tool.

## Suture size — MedicalPro

Suture size. The main mistakes when ordering suture material.

Every day, employees of the MedicalPro Company encounter errors in the dimensions of the suture material, which are made by our customers when placing orders for suture surgical material.

Let’s look at the main mistakes, but first we will talk about the existing suture size rulers.

In modern surgery, there are two main dimensions — the metric size and the conditional size.

Metric size, used where the metric system of measurement is adopted, and this is in Europe and the countries of the former USSR. It is designated by the following symbols (MP) (M) (METRIC) (EP), they denote the same «Metric size». By the way, the designation EP stands for European Pharmacopeia. The numerical value of the size itself is written quite simply 1,2,3,4,5,6,7 and there is one very convenient moment here: for example, to find out the real thickness of the suture thread in millimeters, you need to divide the metric size by 10! For example, for an M.P.4 suture, the thread thickness is 0.4 mm, and for EP1.5, the thread thickness is 0.15 mm.

Conventional size, adopted in the USA. It is designated by the symbols (USP) which is an abbreviation for United States Pharmacopeia. The numerical value of the conditional size is written a little more complicated using fractions, for example 2/0 3/0 4/0 5/0, as well as integers 0, 1, 2, it is also written with a hyphen 2-0 3-0 4-0 5 -0

Global manufacturers of suture material such as Ethicon, Medtronic, B. Braun, Resorba and others, given the fact that their products are imported all over the world, indicate both sizes on the packages, i. e. metric and conditional. Russian manufacturers Lintex, PTO Medtekhnika, Repromed, Tatkhimfarmpreparaty, Politekhmed naturally adopted this useful experience.

There is a table for converting nominal suture size to metric size and vice versa. Here is the table.

 Nominal size of all threads except Catgut, USP Nominal size Catgut, USP Metric, EP True size, mm 6/0 7/0 0.7 0.070-0.099 5/0 6/0 1 0.100-0.149 4/0 5/0 1.5 0.150-0.199 3/0 4/0 2 0.200-0.249 2/0 3/0 3 0.300-0.339 0 2/0 3.5 0.350-0.399 1 0 4 0.400-0.499 2 1 5 0. 500-0.599 3 and 4 2 6 0.600-0.699 5 3 7 0.700-0.799 6 4 8 0.800-0.899 7 5 9 0.900-0.999 8 6 10 1.000-1.099

An attentive person will immediately notice that the dimensions of the suture material Catgut are shifted one point up.

Example Prolene (synthetic thread): 3/0 corresponds to EP2, and Catgut 3/0, respectively, one point more i.e. ep3.

It’s really quite simple if you take one minute and carefully study this table.

Now let’s get back to the typical errors in the size of the suture when ordering.

Examples:

1. — We want to order Vicryl 2 «two».

It is necessary to clarify what is meant by the conditional size or metric size of the Vicryl thread.

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