Basic Compression Spring Calculation Formulas:
Sometimes, you might only have a couple of your compression spring's dimensions but in order to calculate other things such as rate and travel, you'll need to know a bit more. Here you will see a couple examples of different scenarios where a certain spring dimension is needed.
To Calculate Wire Diameter:
If you only have your Outer Diameter (OD) and Inner Diameter (ID) but need Wire Diameter (WD), you must subtract your Inner Diameter (ID) from your Outer DIameter (OD) and then divide the result by two as shown in the formula below:
(Outer Diameter – Inner Diameter) ÷ 2 = Wire DIameter
(OD - ID) ÷ 2 = WD
To Calculate Outer Diameter from Inner Diameter:
Multiply your Wire Diameter by two and then add it to your Inner Diameter; as shown in the formula below.
2 * Wire Diameter + Inner Diameter = Outer Diameter
2WD + ID = OD
To Calculate Inner Diameter from Outer Diameter:
Multiply your wire diameter by two and then subtract the result from your Outer Diameter; as shown in the following formula.
Outer Diameter – 2 * Wire Diameter = Inner Diameter
OD – 2WD = ID
To Calculate Mean Diameter:
This specific dimension is calculated by taking one wire diameter and subtracting it from your compression spring's outer diameter or adding it to the inner diameter as shown below.
Outer Diameter – Wire Diameter = Mean Diameter
OD – WD = MD
Inner Diameter + Wire Diameter = Mean Diameter
ID + WD = MD