Torsion Spring Rules & Formulas

Rules and Formulas


Door Weight: (1) Divide the total spring(s) IPPT by the cable drum multiplier

(2) Multiply the spring IPPT by the number of turns, and then divide by the Hi Moment Arm


High Lift: Measure the distance from the top of the closed door to the bottom of the horizontal track

IPPT: Inch Pounds Per Turn.  Force spring exerts per 1 turn of the spring

IPPT Required: Multiply the door weight by the Hi Moment Arm, and then divide by the number of turns


Spring ID: Measure the outside diameter, and then subtract twice the wire diameter


Spring Conversion: Always convert torsion springs to a spring of equal or greater wire diameter


Spring Growth-Torsion: Multiply the number of turns by the wire diameter to find spring growth


Spring Stretch-Extension: The stretch of an extension spring is always ½ the door height


Spring Length: Multiply the wire diameter by the total number of coils in the spring


Wire Size: Measure a length of the spring, then divide by the number of coils within that length

About Frank

I am a second generation garage door professional. I have over 35 years of experience in Service, installation, sales, marketing, management and customer service related to the garage door industry. My wife June, brother Clint and son Lucas are also garage door professionals with a combined 60+ years of experience in this industry.