Spring calculator
What garage door spring do you have?
Four measurements off the spring that is already up there, and you have the exact part to order. No sign-up, and nothing to install.
What you have
0.2253"
wire size
Read this to the supplier
0.2253" wire · 2" inside diameter · 32" long · right wound
Red cone. Usually the right-hand side, looking out. Springs come in pairs on a double door and the two wind opposite ways — order both, and check the second one rather than assuming it matches.
Never change your own springs
A torsion spring on a double garage door holds enough stored energy to break an arm, take out teeth, or worse. It is wound under tension with two steel bars, and if one slips it goes at the speed of the thing it was holding up. People are seriously injured doing this every year, and some are killed. There is no YouTube video that makes this safe, and the part costs less than the emergency room.
The tell that a spring has gone: the door suddenly feels enormously heavy, the opener strains and stops, or there is a loud bang from the garage and then nothing works. If you can see a gap in the coil above the door, that is a broken spring. Leave the door where it is and ring somebody.
How to take the four measurements
Measuring a torsion spring
- Wire size. Press 20 coils tightly together and measure across them. Divide by 20. Twenty coils at 4½" is a 0.2253" wire. Do not use a caliper — it reads the curve of the coil and comes out high, which is the single most common way people order the wrong spring.
- Inside diameter. Across the inside of the coil, not the outside. On a house it is nearly always 1¾", 2" or 2¼".
- Length. The coiled part only. The cones on each end are not part of it.
- Wind direction. Red cone is right wound, black cone is left wound. A double door has one of each and they are not interchangeable.
Colour codes are not on this page on purpose. They vary between manufacturers and they are not a measurement. Measure the coils.
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Roughly what the door weighs
Weight is what decides the spring
The spring is matched to the door, not to the opening. Two 16×7 doors can be a hundred pounds apart depending on the steel and the insulation, which is why the same size takes different springs.
| Door | Plain steel | Insulated |
|---|---|---|
| 8x7 | 85–110 lb | 110–140 lb |
| 9x7 | 95–125 lb | 120–155 lb |
| 10x7 | 105–140 lb | 130–175 lb |
| 16x7 | 150–180 lb | 170–280 lb |
| 16x8 | 170–205 lb | 195–320 lb |
| 18x7 | 170–200 lb | 190–300 lb |
| 18x8 | 190–225 lb | 215–340 lb |
Wide ranges because a 2" sandwich door is close to double a plain single-skin one at the same size. A scale beats this table.
Cycles
Why the last one only lasted six years
A cycle is one open and one close. An average household does 1,100 to 1,500 a year. That is the whole explanation, and it is worth knowing before you buy the cheapest one again.
| Grade | Cycles | At 4 openings a day | What it means |
|---|---|---|---|
| Standard | 10,000 | about 7 years | What comes on most new doors, and what the cheapest replacement will be. |
| Long-life standard | 15,000 | about 10 years | A small upcharge for half again the life. |
| High cycle | 25,000 | 14 to 20 years | Worth it on a door that is also the front door. |
| High cycle, heavy | 50,000 | 20 years or more | Longer spring, thicker wire. Usually outlives the opener. |
The question everybody asks next
How many turns?
A quarter turn for every 3 inches of door height. A 7 ft door is 84 inches, so 84 ÷ 3 = 28 quarter turns, or 7 full turns.
In practice most doors finish a little above that, because the spring is rarely a perfect match for the door's weight. Which is the point: the number is not what makes a door right.
The test is the door itself. With the opener disconnected, lift it halfway and let go. If it stays put, it is balanced. If it drops or rises, the tension is wrong — and correcting it means standing under a wound spring with two bars.
Exact price
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