Helpful Conversion Charts for Coil Spring Measurements
Stock Springs Made Simple
When looking for a stock spring you need to measure and know what dimensions you want the spring to have. Since our customer base is from all over the world, we understand that not everyone is used to decimals or inches, sometimes fractions or millimeters are the most used form of measurement for a person. This can make it a bit challenging when looking for a coil stock spring that meets your needs. At StockSpringsCatalog.com we always try to make things easier for our customers and so we want to share a few charts and helpful tips that might make all the difference when trying to measure or find the stock spring you need.


Decimals and Common Fractional Coil Compression Spring Sizes
Decimals are often used in the spring world to describe the size and shape of a spring. For example if you are looking for a coil compression spring with an outer diameter of half an inch we would write 0.5 in. Outer Diameter (OD). In this way we talk about the different dimensions such as free length, diameters, wire thickness (also known as wire diameter) etc. However, sometimes people might look for a spring based on the fractional number. In this case we can consider the most common fractional numbers such as ¼ one quarter, ½ a half, etc. That is why we also have a list of fractional springs based on the fractional outer diameter size. You can take a look at the common fractional sizes for compression springs: SEARCH COMPRESSION SPRINGS IN COMMON FRACTIONAL SIZES
Written and Spoken Decimals and Fractions in Coil Springs
Another important thing to note is that the way we say decimals and fractions may make them sound like different numbers when in reality we might be referring to the same size spring. So for example if I need a spring that is 0.250 inch in length but I am calling over the phone to place an order or ask about stock options in this size I might say “ I need a spring with a length of two hundred fifty thousands of an inch” I might also say “I need a spring that is a quarter inch long.” Either of those phrases would mean the same thing but they sound different. This may sound confusing but it isn’t. To simplify this, you can take a look at the following chart and use it as reference:
Decimal & Fraction Conversion Chart
| Decimal | Written & talked about | Fractions | ||
|---|---|---|---|---|
| 0.125 = | One hundred twenty five thousands = | 1/8¨ | ||
| 0.250 = | Two hundred fifty thousands = | 1/4¨ | ||
| 0.375 = | Three hundred seventy five thousands = | 3/8¨ | ||
| 0.500 = | Five hundred thousands = | 1/2¨ | ||
| 0.625 = | Six hundred twenty five thousands = | 5/8¨ | ||
| 0.750 = | Seven hundred fifty thousands = | 3/4¨ | ||
| 0.875 = | Eight hundred seventy five thousands = | 7/8¨ | ||
| 1.000 = | One inch = | 1¨ inch |
English and Metric System in Coil Spring Measurements
Another common conversion we make when it comes to coil springs is between the imperial and metric system. The imperial system (commonly known as the “English system”) uses inches while the metric system uses millimeters. Regardless of which measuring system you are more comfortable with our online coil spring tools are created to convert and be used with either system. Just be sure to select the correct measuring system you will use before typing in your measurements. You will see the following phrase:
Choose Your Unit of Measure:
in our Spring Finder tool and then you can click on whether you want to fill out the dimension ranges based on the English system or the Metric system.
Either way we thought it would be helpful to explain the conversion and provide a useful chart that gives you some common conversions of millimeters to inches.
How to convert MM to decimal inches
You can convert millimeters to decimal inches in one of two ways:
Divide the number of millimeters by 25.4
or Multiply the number of millimeters by 0.03937
Either way will work to convert MM into decimal inches.
EXAMPLES:
3 mm X 25.4 = 0.1181” inches
4 mm X 25.4 = 0.1575” inches
5 mm X 0.03937 = 0.1969” inches
How to convert decimal inches into mm
You can convert decimal inches into millimeters one of two ways:
Multiply the number of decimal inches by 25.4 to convert them into millimeters.
or Divide the number of decimal inches by 0.03937
Either way will work to convert decimal inches into millimeters (mm)
EXAMPLES:
0.1969” inches X 25.4 = 5 mm
0.236” inches X 25.4 = 6 mm
0.2755” inches X 0.03937 = 7 mm
Chart of Millimeters Converted Into Inches
Millimeters converted to inches in decimals
| Millimeters (mm) | Inches (¨) (decimal) |
|---|---|
| 0.01 mm | 0.0004 ¨ |
| 0.1 mm | 0.0039 ¨ |
| 1 mm | 0.0394 ¨ |
| 2 mm | 0.0787 ¨ |
| 3 mm | 0.1181 ¨ |
| 4 mm | 0.1575 ¨ |
| 5 mm | 0.1969 ¨ |
| 6 mm | 0.2362 ¨ |
| 7 mm | 0.2756 ¨ |
| 8 mm | 0.3150 ¨ |
| 9 mm | 0.3543 ¨ |
| 10 mm | 0.3937 ¨ |
Get The Right Stock Springs Fast and Easy
Regardless of the measurement system or style that you prefer, we are here to help. Whether you need a few stock springs for prototyping or are looking for a coil replacement spring, you can easily find the stock spring you need at Stock Springs Catalog. For more information or assistance in buying a quality stock spring at an affordable price contact us at: (951) 276-2777