When ordering extension springs you can use 2 different methods to determine the correct size of replacement springs needed.

Method 1:

1. Determine Wire Size
2. Measure the Inside Diameter to the nearest 1/32"
3. Determine the Spring Length (do not include loops in this measurement)
4. Specify Type of Ends (double loops, single loops, or clips)
5. Specify Type of Door (sectional, one piece or taylor sectional)
   1. Example: .177 - 1 3/32" ID - 25"

Method 2:

1. Measure Spring Length
2. Determine Amount of Stretch (Amount of stretch is half the door height)
3. Furnish the Door Weight
4. Specify Type of Ends (double loops, single loops, or clips)
5. Specify Type of Door (sectional, one piece or taylor sectional)
   1. Example: 25" - 42" 150 lbs.

Common Extension Spring Lengths

Extension spring lengths vary by manufacturer. However, the chart below summarizes the length and the stretch for common extension springs.