In the workshop it is very necessary to make **Conversion Between Millimeters** for handle units in both inches and millimeters, as we usually find drill bits, wrenches, measuring instruments, tools, spare parts and other elements that are in the two systems of measurement, this is where the knowledge and handling of a very important issue, this is **The conversion between millimeters and inches and vice versa.**

In this article I share with you the cases and the way I do the conversions between units.

## Case 1. Conversion from Inches to Millimeters.

To convert Inches to Millimeters, the following rule should be observed: **“1 inch is equivalent to 25.4 millimeters”.**

Let’s see an example:

**What is the equivalent of 3/4 of an inch in millimeters?**

To make the conversion, I use the following method:

In this case, you can simplify the inches because they are present in both the numerator and the denominator, then:

If you make: 25.4 divided by 1 is 25.4, then:

Now, if you put 1 to 25.4 mm. as the denominator, the value is not affected, as it means that 25.4 is divided by 1, which results in 25.4 being equal to:

Now, to multiply fractionals you proceed by multiplying numerators with numerators and denominators with denominators like this:

Finally, we make the division of the numerator with the denominator like this:

This gives the final result: 19.05, then:

## Now let’s go with a case in Thousandths of an Inch:

If we have a fraction of an inch, then this same fraction is equivalent to a number in thousandths of an inch, this corresponds to that a fraction is a division between the numerator and the denominator. Example:

Examples of thousandths of an inch are: **0.500in., 0.750in., 0.567in., 0.001in., 1.000in.**, etc.

Let’s see an example of conversion from thousandths of an inch to millimeters:

What does 0.5625? equal in millimeters?

The procedure is the same as in the first example:

If we cancel the inches, we get:

25.4 mm divided by 1 is 25.4 mm. Now if we multiply 0.5625″ by 25.4 mm is **14.2875 millimeters**.

## Case 2. Conversion from Millimeters to Inches.

As in the previous case, the only thing we must remember is the equivalence between millimeters and inches, that is, one inch is equivalent to 25.4 millimeters.

Examples:

What does 10 millimeters in inches equal?

If we solve in the same way as to convert inches to millimeters, like this:

If we cancel the millimeters because they are in both the numerator and the denominator then we get:

Now, if we divide 1 by 25.4 = 0.03937″

So: 10(0,03937) and if we do the multiplication normally, obtaining as result 0,3937″

From this we can also conclude that: **1 millimeter is equivalent to 0.03937″**

**Another example:**

What does 12.7 millimeters in inches equal?

We multiply 12.7(0.03937), that is the equivalent of one millimeter to inches: then the result is: 0.500″

These are the forms or modes I usually use when I need to do the **Conversion Between Millimeters to Inch and vice versa**.

We can also convert millimeters to fractions of an inch, so I recommend you see the link that goes to this article: **How to Convert Millimeters to Fractional Inch Known**

As usual, in Easy Metalworking, I share with you the tips, ideas and formulas that will help you in your **machining jobs**.

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