Need Help?

Get in touch with us


Millimeter – Definition, formula, and its Conversions

Apr 12, 2022

Millimetres are one of the measurement units that are frequently used in mathematics. It is used by engineers, surveyors, manufacturers, industrialists, and even by students at school. A millimetre is a unit of length. The prefix ‘milli’ means one thousand in Latin. Hence, one millimetre is one-thousandth of a meter. Here are the other critical points that you must keep in mind: 

  • The symbol of millimetres is mm. 
  • There are ten millimetres in one centimetre. 
  • One millimeter is equal to 1000 micrometers.
  • One millimeter is equal to 1 000 000 nanometers.
  • One inch is equal to 25.4 millimeters.
  • One millimeter is equal to 0.03937 inches. 

What does a Millimeter mean?

The meter is defined as the length of the path traveled by light in a vacuum during a time interval of 1/299792458 of a second. This definition has been followed since 1983 though it was originally recorded in 1800-10 in French. 

A millimeter is 1/1000 of a meter. Hence, a millimeter is a distance traveled by light in 1/299792458000 of a second. It is sometimes denoted as ‘mili’ and represented as mm. The term ‘mili’ confuses the US, which traditionally means a thousandth of an inch. The actual millimeter is 0.03937 of an inch. 

Facts about millimeters 

  • The metric ruler, which students carry for their school as a part of their stationery, has the smallest unit of measurement, millimeters. If the scale is high-quality, then the probability is it might carry up to 0.5 mm. 
  • Microwaves, having a frequency of 300GHz, have a wavelength of 1 mm. These wavelengths are used in data transmission that has the potential to transfer the data at 10 gigabytes per second. 
  • The smallest distance the human eye can resolve is around 0.02 to 0.04 mm, near about the width of a human hair. 
  • A sheet of paper has a thickness of 0.07 mm that can be as thick as 0.18 mm. An ordinary paper has a thickness of about 0.1 mm. 

Milliliters to Liters 

After understanding what a millimeter means, let us study how to convert millimeters to liters. Since a millimeter is a unit of length and a liter is a unit of capacity, the correct unit to convert to a liter will be cubic millimeters, denoted by the capacity unit. 


1 cubic meter = 1000 liters 

1 cubic meter = 1000 000 000 cubic millimeter

Hence, 1 liter = 1000 000 cubic millimeter 

Milliliters to Ounces 

Now, let us learn how many millimeters in an ounce are there. If you wonder how many millimeters in an ounce are there, the answer is 29.573. This is the liquid ounce of the US. The UK ounce will differ a bit. 


1 cubic meter, the unit of volume, is 1000 000 000 cubic millimeters. Hence, 1 cubic meter is equal to 33814.022 oz. Other conversion units are given below:

  • 1 milliliter to oz = 0.03381 oz
  • 10 milliliter to oz = 0.33814 oz
  • 20 milliliter to oz = 0.67628 oz

Millimeter to Inches 

Millimeters to Inches Conversion: 

While inches are used in the US customary system of measurements, the millimeter unit is specified in the worldwide system of units known as SI units. This millimeter-to-inches method and the millimeter-to-inches conversion table make converting between millimeters and inches as well as vice versa very simple. One millimeter is equal to 0.03937007874 inches, therefore to convert from inches to millimeters, multiply the result by 0.03937007874. 

d(in) = d(mm) × 0.03937007874 

Since 1 in = 25.4 mm, we may also divide the length of a millimeter to convert it to an inch. Consequently, the equation is 

d(in) = d(mm) ÷ 25.4 


  • d(in) = value in inches 
  • d(mm) = value in millimeters 

Example 1: Convert 16mm to in. 

Solution: Using the formula, 

d(in) = d(mm) × 0.03937007874in 

d(in) = 16 × 0.03937007874in 

d(in) = 0.629921259 in 

Therefore, 16mm = 0.629921259in. 

Liters to Milliliters 

Liter and milliliter are the units of volume. Hence, 1 liter is equal to 1000 milliliter. The other conversions of the volume units are given below in the table. 

Kiloliter 1000 liter (l, small letter of L)
Hectaliter 100 l
Decaliter 10 l
Liter l
Deciliter 0.1 l
Centiliter 0.01 l
Milliliter 0.001 l

How many Milliliters are in a teaspoon? 

A teaspoon is a culinary measure, which is ⅓ of a tablespoon. A US teaspoon has 4.92892 milliliters in a teaspoon. It is also referred to as a flat spoon. A teaspoon is used to stir tea, measure sugar, and play games such as spoons and many other things. However, the unit of conversion will change for the UK teaspoon.  

Conversion tables 

The various conversion tables will help you quickly get millimeters to the desired unit. 

Kilometer 1000 m 
Hectometer 100 m 
Decameter 10 m 
Meter m
Decimeter 0.1 m 
Centimeter 0.01 m 
Millimeter 0.001 m 
Meter (m)Millimeter (mm)
0.01 m10 mm
0.1 m100 mm
1 m1000 mm
2 m2000 mm
3 m3000 mm
5 m5000 mm
10 m10000 mm
20 m20000 mm
50 m50000 mm
100 m100000 mm
Millimeters Inches 
1 mm 3/64 inch
2 mm 5/64 inch 
3 mm ⅛ inch 
4 mm 5/32 inch 
5 mm 13/64 inch 
6 mm 15/64 inch 
7 mm 9/32 inch 
8 mm 5/16 inch 
millimeter to kilometer (km)0.000001
millimeter to meter (m)0.001
millimeter to decimeter (dm)0.01
millimeter to centimeter (cm)0.1
millimeter to micrometer (micron)1,000
millimeter to nanometer (nm)1,000,000
millimeter to ångström10,000,000
millimeter to league0.0000002071
millimeter to a mile (mi)0.0000006214
millimeter to land0.0000006214
millimeter to furlong0.000004971
millimeter to bolt0.00002734
millimeter to chain0.00004971
millimeter to pole0.0001988
millimeter to the rod (rd)0.0001988
millimeter to perch0.0001988
millimeter to the yard (yd)0.001094
millimeter to foot (ft)0.003281
millimeter to feet and inches (x’y”)0.03937″
millimeter to span0.004374
millimeter to hand0.009843
millimeter to inch (in)0.03937
millimeter to line0.4724
millimeter to mil39.37
millimeter to microinch39,370
millimeter to furlong0.000004971
millimeter to Ramsden’s (engineers’) chain (ch)0.00003281
millimeter to Gunter’s (surveyors’) chain (ch)0.00004971
millimeter to Gurley’s chain (ch)0.00009942
millimeter to Gunter’s (surveyors’) pole0.0001988
millimeter to Gunter’s (surveyors’) yard0.001094
millimeter to Ramsden’s (engineers’) link0.003281
millimeter to Gunter’s (surveyors’) link0.004971
millimeter to Gurley’s link0.004971
millimeter to Gunter’s (surveyors’) foot (ft)0.003281
millimeter to the nautical league (Naut. league)0.00000018
millimeter to a nautical mile (Naut. mi)0.00000054
millimeter to cable length (cbl)0.0000054
millimeter to fathom (fath)0.0005468
millimeter to US nautical mile0.0000005396
millimeter to US fathom (fath)0.0005468
millimeter to US cable length0.000004557

Understanding Millimeters by examples 

Example 1: Convert 50 cm to mm. 

Solution: We know, 1 cm = 10 mm. Therefore, 50 cm = 50 x 10 mm = 500 mm. 

Hence, 50 cm is equal to 500 mm. 

Example 2: Convert 6790 millimeters to meters.

Solution: We know that 1 meter = 1000 millimeters. We need to set up the conversion so that the desired unit will be canceled out. In the question mentioned above, we need meters in the end. Hence,

Distance in m = distance in mm x 1 m / 1000 mm

Distance in m = 6790 / 1000 m 

Distance in m = 6.790 m. 

Example 3: How many millimeters are there in 6000 liters?

Solution: We know, 1 cubic millimeter is equal to 10-6 liters.

In other words, 1 liter is equal to 106 cubic millimeters. Therefore, 6000 liters is equal to 

6000 liter x 106 = 6000 x 106 millimeters. 

Note: Here is a table for your reference for other values of liters 

1 Liter = 1000000 Cubic millimeters10 Liters = 10000000 Cubic millimeters2500 Liters = 2500000000 Cubic millimeters
2 Liters = 2000000 Cubic millimeters20 Liters = 20000000 Cubic millimeters5000 Liters = 5000000000 Cubic millimeters
3 Liters = 3000000 Cubic millimeters30 Liters = 30000000 Cubic millimeters10000 Liters = 10000000000 Cubic millimeters

Example 4: Convert 500 milliliters to ounces. 

Solution: We know that 1 fluid ounce is equal to 29.573 milliliters. Therefore, to convert mm to the ounce, you should divide 500 by 29.573. 

Therefore, the value will be 16.907 fluid ounces. 

Example 5: Jelly’s friend asked her to measure the length of the showpiece kept in the drawing-room. Jelly took out a ruler that had millimeter markings. She found out the length of the showpiece was 39 millimeters. But her friend wanted to find the length of the showpiece in decimeters. What is the equivalent length in decimeters?

Solution: The length of the showpiece was 39 millimeters. Jelly’s friend wants her to find the length in decimeters. So, let us convert millimeters to decimeters. 

We know, that 1 millimeter is equal to 0.01 decimeters. 

Hence, 39 millimeters will be equal to 0.01 x 39 = 0.39 decimeters. 

Therefore, 39 millimeters is equal to 0.39 decimeters. 

Practice questions based on millimeters 

Q1. Choose the right answer for the given question: Convert 60 mm to cm. 

  1. 0.6 cm
  2. 6 cm
  3. 60 cm
  4. 600 cm 

Q2. Brett wanted to measure the side of a cube using a ruler. However, his ruler only had millimeter markings. He found the side length was 5.7 mm. But his teacher asked him to find the length in decameters. Can you help him do the conversions? 

Q3. Convert the following as indicated:

  1. 456 cm to mm
  2. 7903 mm to an ounce
  3. 2345 teaspoon to mm
  4. 7823 millimeters to liters 
  5. 2310 liters to millimeters 

Frequently Asked Questions

1. What is difference between a millimeter and a micrometer?

Ans. A millimeter (mm) is a unit of measurement that is equal to one-thousandth of a meter, or approximately 0.03937 inches. A micrometer (μm) is a unit of measurement that is equal to one-millionth of a meter, or about 0.0000394 inches.

2. Which is greater a millimeter or a meter?

Ans. A millimetre is greater than a meter. There are 100 millimetres in a meter, so each millimetre is 1/100th of a meter.

3. How big is a millimetre’s actual size?

Ans. A millimetre is a tiny little thing. It’s smaller than an inch, and it’s even smaller than a centimetre. If you lined up one thousand millimetres side by side, they’d only be as tall as the edge of your fingernail!

4. How many inches is one millimetre?

Ans. One millimetre is equal to 0.0393700787 inches.

5. How big is 13 millimetres?

Ans. 13 millimetres is about 0.5 inches, or about the diameter of a pencil.



Related topics

Addition and Multiplication Using Counters and Bar-Diagrams

Addition and Multiplication Using Counters & Bar-Diagrams

Introduction: We can find the solution to the word problem by solving it. Here, in this topic, we can use 3 methods to find the solution. 1. Add using counters 2. Use factors to get the product 3. Write equations to find the unknown. Addition Equation: 8+8+8 =? Multiplication equation: 3×8=? Example 1: Andrew has […]


Dilation: Definitions, Characteristics, and Similarities

Understanding Dilation A dilation is a transformation that produces an image that is of the same shape and different sizes. Dilation that creates a larger image is called enlargement. Describing Dilation Dilation of Scale Factor 2 The following figure undergoes a dilation with a scale factor of 2 giving an image A’ (2, 4), B’ […]

Numerical Expressions

How to Write and Interpret Numerical Expressions?

Write numerical expressions What is the Meaning of Numerical Expression? A numerical expression is a combination of numbers and integers using basic operations such as addition, subtraction, multiplication, or division. The word PEMDAS stands for: P → Parentheses E → Exponents M → Multiplication D → Division  A → Addition S → Subtraction         Some examples […]

System of linear inequalities

System of Linear Inequalities and Equations

Introduction: Systems of Linear Inequalities: A system of linear inequalities is a set of two or more linear inequalities in the same variables. The following example illustrates this, y < x + 2…………..Inequality 1 y ≥ 2x − 1…………Inequality 2 Solution of a System of Linear Inequalities: A solution of a system of linear inequalities […]


Other topics