Free Garage Door Torsion Spring Calculator
Calculate IPPT, check spring compatibility, and find the right replacement spring for your door weight and height.
Torsion Spring Calculator
Find the right spring for your door weight and height
Door Specifications
Spring Specifications
Safety Warning
Garage door spring replacement is dangerous and should only be performed by trained professionals. Torsion springs are under extreme tension — a spring that snaps during installation can cause serious injury or death. This calculator is for educational and planning purposes only. Call us at (403) 990-9536 for professional spring replacement in Calgary.
How the IPPT Formula Works
IPPT (Inch-Pounds Per Turn) measures how much torque a spring produces for each turn of wind. The formula is: IPPT = (E × d⁴) / (10.8 × Dm × Na)
- E = 28,500,000 psi (modulus of elasticity for spring steel)
- d = wire diameter in inches
- Dm = mean coil diameter (inside diameter + wire size)
- Na = number of active coils
Required IPPT
Required IPPT = (Weight × Drum Radius) / (Turns × Springs × 12). This calculator uses a standard 4" cable drum. A spring should be within 90–110% of the required IPPT.
Not Sure About Your Spring? Call Us.
Our technicians measure your door, identify the exact spring, and replace both springs same-day.