Construction
Garage Door Torsion Spring Calculator
Door weight + drum size + lift = your spring spec. We estimate IPPT, wire gauge, and length using industry formulas. Read the safety notice below before touching a real spring.
⚠️ Safety notice — read this before you turn any winding bar
A wound torsion spring stores enough energy to break bones, take fingers off, or fatally injure you if it slips or breaks during winding. This calculator gives you an estimate for ordering and sizing. It is not installation instruction. Hire a licensed garage door technician unless you have the right winding bars, vise grips, and hands-on training. ClutchCalcs is not liable for installation outcomes.
Wire size reference (residential)
Measure 20 coils of an existing spring, divide by 20 to get wire diameter:
| Wire size | Wire dia. (in) | Typical IPPT @ 1.75" ID |
|---|---|---|
| .207 | 0.207 | ~12 |
| .218 | 0.218 | ~15 |
| .225 | 0.225 | ~17 |
| .234 | 0.234 | ~20 |
| .243 | 0.243 | ~23 |
| .250 | 0.250 | ~26 |
| .262 | 0.262 | ~32 |
| .273 | 0.273 | ~38 |
| .283 | 0.283 | ~44 |
FAQ
Where does IPPT come from? +
IPPT = inch-pounds per turn. The moment a spring exerts when wound one full turn. Door weight × drum radius / 12 = required moment, divided by turns to lift = IPPT per spring (×2 if dual spring setup).
My existing spring is broken — can I just match it? +
Read the cone — most springs have wire size and length stamped. Or measure: 20 coils ÷ 20 = wire dia. Spring length stretched out = length. Plus you need ID (1.75" or 2" residential typically).
Why higher cycle count = more expensive? +
Springs are sized so that the working stress is below the fatigue limit. Higher cycle springs use larger wire + longer length so they're not stressed as hard each cycle. Costs 30–80% more.
Should I install this myself? +
Only if you have winding bars (correct length, sized to your cone), proper bracing, and you've done it before with supervision. The energy stored in a fully wound spring can launch a steel bar across a garage faster than you can move. Pay a pro.
Lifetime vs 25K cycle? +
"Lifetime" warranty springs are usually rated for 50K+ cycles \u2014 about 20 years at 7 cycles/day. Standard 10K springs last ~5 years for typical usage.