How to Measure a Garage Door Torsion Spring
Replacing a garage door torsion spring starts with one job you have to get right: measurement. If any of the four key measurements is even slightly off, the new spring won’t lift your door properly — and the wrong spring can be dangerous.
The good news is that measuring a torsion spring is straightforward once you know what to look for. This guide walks you through the four measurements every technician takes before ordering a replacement, how to tell right-wound from left-wound springs, and what the IPPT number means. Whether you’re a homeowner replacing a snapped spring yourself or a technician sizing up a new install, this is everything you need to know before you order.
Safety First!
Garage door torsion springs are under extreme tension. A broken spring can weigh as much as a car — the tension it stores has enough force to cause serious injury or death. Never attempt to unwind or handle a spring that is still installed and under tension without proper winding bars and training. When in doubt, hire a licensed garage door professional. Measurements can be taken safely; installation is where the risk is.
Why accurate measurement matters
A torsion spring is essentially a coiled length of wire designed to hold and release energy as your garage door goes up and down. Every spring is engineered for a specific door weight and travel distance. The four measurements you’re about to take tell you exactly how much energy that spring can store and release.
If you install a spring that’s:
- Too weak (too small): Your door will feel heavy, the opener will strain, and the spring will fail early — often within months instead of years.
- Too strong (too large): The door will slam upward and be unsafe to close. It also puts excessive stress on the opener, cables, and hardware.
- Wound the wrong direction: The spring will unwind itself the moment tension is applied. It won’t work at all.
That’s why we need all four measurements, not just one or two.
The four measurements you need
Every garage door torsion spring is defined by these four specifications:
1. Wire diameter — the thickness of the wire itself
2. Inside diameter (ID) — the size of the hollow center of the spring
3. Overall length — how long the spring is when relaxed
4. Winding direction — whether it winds to the right or left
You’ll need a tape measure (or ruler) and a caliper for the wire diameter. If you don’t have a caliper, a regular ruler with millimeter markings can work, though it’s less precise.
Let’s go through each measurement in detail.
Measurement 1: Wire diameter
What it is: The thickness of the individual wire that makes up the coil.
Why it matters: Wire diameter is the single biggest factor in how much lifting force the spring provides. A thicker wire holds more energy per turn.
How to measure it: The most accurate way is with a caliper. Measure across the wire on one coil of the spring — that gives you the true wire diameter in inches.
If you don’t have a caliper, here’s a technician’s trick: measure 10 coils as they sit next to each other along the spring, then divide by 10. So if 10 coils together measure 2 inches, your wire diameter is 0.200″. This works because the coils sit tightly against each other, and 10 measurements averaged gets you closer to the true value than a single reading.
Common wire diameters for garage door torsion springs:
- 0.192″ — lightweight residential doors
- 0.207″ — most common residential doors
- 0.218″ — heavier residential and light commercial
- 0.225″ — commercial doors
- 0.234″ — heavier commercial doors
- 0.243″, 0.250″, 0.262″, 0.273″, 0.283″, 0.295″ — commercial and industrial applications
Write down your measurement. This is the most important number.
Measurement 2: Inside diameter
What it is: The diameter of the hollow space in the middle of the coiled spring.
Why it matters: The inside diameter must match the shaft the spring rides on. If the ID is too small, the spring won’t slide onto the shaft. If it’s too large, it’ll wobble and fail early.
How to measure it: Look at the end of the spring and measure across the empty circle in the middle — inside edge to inside edge. Don’t measure the outside of the coil.
Common inside diameters:
- 1.75″ — the most common size for residential garage door torsion springs
- 2″ — used on many commercial doors and heavier residential doors
- 2 5/8″ (2.625″) — used on some commercial and industrial doors
Almost every residential garage door will use either 1.75″ or 2″. Commercial doors will often be 2″ or 2 5/8″.
Measurement 3: Overall length
What it is: How long the spring is from end to end, measured along the coil.
Why it matters: Length determines how many turns of energy the spring can hold. Longer springs = more lifting travel = more turns available.
How to measure it: Measure the length of the coiled portion only — do NOT include the cones or fittings on the ends. Just the coil itself, in inches, from where the coil starts on one end to where it ends on the other.
If your spring is broken (snapped in half), measure both pieces separately, then add them together. Include the length of the gap where the coil separated (usually 1-2 inches).
Common lengths range from 15″ to 48″, though most residential springs are between 20″ and 36″.
Measurement 4: Winding direction (right-wound vs left-wound)
What it is: Whether the wire coils to the right or the left as you look at it from one end.
Why it matters: Most garage doors have two springs, and they must be wound in opposite directions — one right-wound and one left-wound — so that the tension balances. Ordering the wrong wind direction is one of the most common mistakes DIY buyers make.
How to determine it:
Look at the end of the spring, at the last coil. Ask yourself: does the wire come out of the top of the coil going toward the right, or toward the left?
– If the top of the coil moves toward the right → right-wound
– If the top of the coil moves toward the left → left-wound
The easier trick used across the industry: color coding on the winding cones.
– RED cone = Right-wound spring
– BLACK cone = Left-wound spring
This color code is nearly universal across manufacturers. If the cones (the metal fittings on each end) are painted, you can usually identify wind direction just by looking at the color.
Which side of the door does each go on? Standing inside your garage, looking out:
- The right-wound (red) spring goes on the left side of the center bracket
- The left-wound (black) spring goes on the right side of the center bracket
What IPPT means (and when it matters)
You may see torsion springs listed with an IPPT value. IPPT stands for Inch-Pounds Per Turn — it’s a measurement of how much lifting force the spring generates per each 360-degree rotation when it’s wound up.
For most garage doors, you don’t need to think about IPPT directly. As long as you have the correct wire diameter, inside diameter, length, and winding direction, the IPPT will be right for that spring.
Where IPPT becomes relevant:
Custom-sized doors where standard springs don’t fit
Commercial installations where the door weight and travel are unusual
Combining springs** on wider doors that need multiple springs to balance
At GAS Hardware, our torsion spring product listings include the IPPT value so professional installers can size springs precisely for a specific door weight.
Formula for reference: Total spring force needed = (Door weight in pounds × High moment arm) ÷ Total turns of the spring. Most people won’t need to calculate this. If you’re replacing an existing spring like-for-like, matching the four measurements is enough.
What to do if your spring is broken
A broken torsion spring is usually easy to identify — you’ll see the coil is separated in one or two places, and your garage door will feel far too heavy to lift.
You can still measure a broken spring:
- Wire diameter: Measure the intact section of the spring using the same method as above.
- Inside diameter: Measure across the hollow center of one of the intact pieces.
- Length: Measure each piece separately, add them together, then add 1-2 inches for the gap where the coil broke.
- Winding direction: Look at either intact piece — the wind direction doesn’t change when a spring breaks.
If your door originally had two springs and only one broke, we strongly recommend replacing both at the same time. Springs installed together age together, and the unbroken one is likely close to failure.
Frequently asked questions
How long do G.A.S Hardware garage door torsion springs last?
The standard rating is **10,000 cycles** (one cycle = one open + one close). However, electrophoretically-coated premium torsion springs by G.A.S Hardware average up to 20,000 to 30,000 cycles, and G.A.S Hardware premium galvanized steel springs are rated up to 70,000 cycles.
10,000 cycles: Standard residential
30,000 cycles: ~20 years of average residential use (G.A.S Hardware Torsions Springs)
50,000 cycles: Extended-life springs for high-traffic homes
70,000 cycles: GAS Hardware’s premium residential galvanized springs
Higher-cycle springs cost more upfront but often outlast the door itself, making them cheaper over the lifetime of the door.
Do I need to replace both springs even if only one broke?
Yes, we recommend it. If your door has two torsion springs, they were installed at the same time and have gone through the same number of cycles. When one breaks, the other is usually near failure too. Replacing both together avoids a second service call in a few months.
Can I install a garage door spring myself?
You can, but you shouldn’t unless you’ve done it before or have professional training. A wound torsion spring stores enough energy to kill a person if it slips. If you attempt DIY installation, use proper winding bars (never screwdrivers), work with the door fully closed, and follow safety procedures exactly.
For most homeowners, the safer path is to buy the correct spring from us and hire a local installer to swap it in — a job that typically takes a pro 30-60 minutes.
Why are there color codes on the spring cones?
The color codes (red for right-wound, black for left-wound) are an industry standard that helps installers identify winding direction at a glance, especially when springs are already installed on a door. It’s not universal to every manufacturer, but it’s the convention for over 95% of the springs sold in the U.S.
What does “IPPT” mean on a torsion spring listing?
IPPT stands for Inch-Pounds Per Turn — it measures how much lifting force the spring provides per each full rotation when wound. Most homeowners don’t need to think about IPPT; matching your existing spring’s wire diameter, inside diameter, length, and wind direction is enough. IPPT matters for custom installations and commercial applications.
Where is the wire diameter measured on a torsion spring?
Wire diameter is measured across the thickness of the wire that forms the coil — not across the whole spring. Use a caliper for the most accurate reading, or measure 10 tightly-packed coils together and divide by 10 for a rough approximation.
Ready to order your replacement?
Once you have all four measurements — wire diameter, inside diameter, length, and wind direction — you’re ready to order.
- Shop torsion springs by size:
1.75″ Inside Diameter Torsion Springs — Most residential doors - 2″ Inside Diameter Torsion Springs — Heavier residential and commercial doors
- Commercial Torsion Springs — 2″ and 2 5/8″ ID for commercial applications
- Galvanized Torsion Springs — Corrosion-resistant for coastal or humid environments
All GAS Hardware torsion springs are constructed from ASTM 229 Class II high-carbon steel and rated for up to 30,000 cycles — three times the industry-standard 10,000-cycle rating. Premium galvanized spring options rated for up to 70,000 cycles are also available.
Not sure which spring you need?
Our sales team can help match your measurements to the right SKU. (Contact Us) We ship from warehouses in Hollywood, FL and Fremont, CA for fast delivery across the U.S.